Blogs...:)

1. Explain MVC (Model-View-Controller) in general?

Model-View-Controller (MVC) is an architectural software pattern that basically decouples various components of a web application. By using the MVC pattern, we can develop applications that are more flexible to changes without affecting the other components of our application.

"Model",is basically domain data.
"View" is the user interface to render the domain data.
"Controller" translates user actions into appropriate operations performed on the model.

2. What is ASP.NET MVC?

ASP.NET MVC is a web development framework from Microsoft that is based on the Model-View-Controller (MVC) architectural design pattern. Microsoft has streamlined the development of MVC based applications using the ASP.NET MVC Framework.

3. What are the differences between ASP.NET MVC and ASP.NET WebForms?

ASP.NET Web Forms use the Page Controller Pattern for rendering layout, whereas ASP.NET MVC uses the Front Controller approach. In the case of the Page Controller Pattern, every page has its own Controller, in other words a code-behind file that processes the request. On the other hand, in ASP.NET MVC, a common Controller for all pages processes the requests.

Follow the link for the difference between the ASP.NET MVC and ASP.NET WebForms.

4. What are the Core features of ASP.NET MVC?

The core features of the ASP.NET MVC Framework are:

Clear separation of application concerns (Presentation and Business Logic)
An extensible and pluggable framework
Extensive support for ASP.NET Routing
Support for existing ASP.NET features

Follow for detailed understanding of above mentioned core features.

5. Can you please explain the request flow in the ASP.NET MVC framework?

The request flow for the ASP.NET MVC Framework is as follows.

The request hits the Controller coming from the client. The Controller plays its role and decides which model to use to serve the request, further passing that model to the View that then transforms the model and generates an appropriate response that is rendered to the client.

6. What is Routing in ASP.NET MVC?

In the case of a typical ASP.NET application, incoming requests are mapped to physical files such as an .aspx file. The ASP.NET MVC Framework uses friendly URLs that more easily describe the user's action but are not mapped to physical files.

The ASP.NET MVC Framework uses a routing engine that maps URLs to Controller classes. We can define routing rules for the engine, so that it can map incoming request URLs to the appropriate Controller.

Practically, when a user types a URL in a browser window for an ASP.NET MVC application and presses the "go" button, the routing engine uses routing rules defined in the Global.asax file to parse the URL and determine the path of the corresponding Controller.

7. What is the difference among ViewData, ViewBag and TempData?

To pass data from a Controller to a View and in a subsequent request, The ASP.NET MVC Framework provides various options, in other words ViewData, ViewBag and TempData.

Both ViewBag and ViewData are used to to communicate between Controller and corresponding View. But this communication is only for the server call, it becomes null if the redirect occurs. So, in short, it's a mechanism to maintain state between Controller and corresponding View.

ViewData is a dictionary object while ViewBag is a dynamic property (a new C# 4.0 feature). Since viewData is a dictionary object it is accessible using strings as keys and also requires typecasting for complex types. On the other hand, ViewBag doesn't have typecasting and null checks.

TempData is also a dictionary object that persists for the life of a HTTP Request. So, Tempdata can be used to maintain data between redirects, in other words from one Controller to another Controller.

8. What are Action Methods in ASP.NET MVC?

As previously stated about request flows in the ASP.NET MVC Framework, a request coming from a client hits the Controller first. Actually the MVC application determines the corresponding Controller using routing rules defined in Global.asax. And Controllers have specific methods for each user actions. Each request coming to the Controller is for a specific Action Method. The following code example, "ShowBooks" is an example of an Action Method.

public ViewResult ShowBooks(int id)
{
var computerBook = db.Books.Where(p => P.BookID == id).First();
return View(computerBook);
}

9. Explain the role of Model in ASP.NET MVC?

One of the core features of ASP.NET MVC is that it separates the input and UI logic from business logic. The role of the Model in ASP.NET MVC is to contain all application logic including validation, business and data access logic except View. In other words input and Controller; in other words UI logic.

The Model is normally responsible for accessing data from some persistent medium such as a database and manipulates it.

10. What are Action Filters in ASP.NET MVC?

If we need to apply some specific logic before or after action methods then we use action filters. We can apply these action filters to a Controller or a specific Controller action. Action filters are basically custom classes that provide a way for adding pre-action or post-action behavior to Controller actions.

For example:

An Authorize filter can be used to restrict access to a specific user or a role.
An OutputCache filter can cache the output of a Controller action for a specific duration

_________________________________________________________________________________________________________

1. What is MVC?

MVC is a framework methodology that divides an application’s implementation into three component roles: models, views, and controllers.

Main components of an MVC application?

1. M - Model

2. V - View

3. C - Controller

“Views” in a MVC based application are the components responsible for displaying the application’s user interface. Typically this UI is created off of the model data (for example: we might create an Product “Edit” view that surfaces textboxes, dropdowns and checkboxes based on the current state of a Product object).

“Controllers” in a MVC based application are the components responsible for handling end user interaction, manipulating the model, and ultimately choosing a view to render to display UI. In a MVC application the view is only about displaying information – it is the controller that handles and responds to user input and interaction.

2- What does Model, View and Controller represent in an MVC application?

Model: Model represents the application data domain. In short the applications business logic is contained with in the model.

View: Views represent the user interface, with which the end users interact. In short the all the user interface logic is contained with in the UI.

Controller: Controller is the component that responds to user actions. Based on the user actions, the respective controller, work with the model, and selects a view to render that displays the user interface. The user input logic is contained with in the controller.

3- In which assembly is the MVC framework defined?

System.Web.Mvc

4- What is the greatest advantage of using asp.net mvc over asp.net webforms?

It is difficult to unit test UI with webforms, where views in mvc can be very easily unit tested.

5- Which approach provides better support for test driven development - ASP.NET MVC or ASP.NET Webforms?

ASP.NET MVC

6- What is Razor View Engine?

Razor view engine is a new view engine created with ASP.Net MVC model using specially designed Razor parser to render the HTML out of dynamic server side code. It allows us to write Compact, Expressive, Clean and Fluid code with new syntax to include server side code in to HTML.

7- What are the advantages of ASP.NET MVC?

Advantages of ASP.NET MVC:

1. Extensive support for TDD. With asp.net MVC, views can also be very easily unit tested.

2. Complex applications can be easily managed

3. Separation of concerns. Different aspects of the application can be divided into Model, View and Controller.

4. ASP.NET MVC views are light weight, as they don't use viewstate.

8- Is it possible to unit test an MVC application without running the controllers in an ASP.NET process?

Yes, all the features in an asp.net MVC application are interface based and hence mocking is much easier. So, we don't have to run the controllers in an ASP.NET process for unit testing.

9- What is namespace of ASP.NET MVC?

ASP.NET MVC namespaces and classes are located in the System.Web.Mvc assembly.

System.Web.Mvc namespace

Contains classes and interfaces that support the MVC pattern for ASP.NET Web applications. This namespace includes classes that represent controllers, controller factories, action results, views, partial views, and model binders.

System.Web.Mvc.Ajax namespace

Contains classes that support Ajax scripts in an ASP.NET MVC application. The namespace includes support for Ajax scripts and Ajax option settings.

System.Web.Mvc.Async namespace

Contains classes and interfaces that support asynchronous actions in an ASP.NET MVC application.

System.Web.Mvc.Html namespace

Contains classes that help render HTML controls in an MVC application. The namespace includes classes that support forms, input controls, links, partial views, and validation.

10- Is it possible to share a view across multiple controllers?

Yes, put the view into the shared folder. This will automatically make the view available across multiple controllers.

11- What is the role of a controller in an MVC application?

The controller responds to user interactions, with the application, by selecting the action method to execute and selecting the view to render.

12- Where are the routing rules defined in an asp.net MVC application?

In Application_Start event in Global.asax

13- Name a few different return types of a controller action method?

The following are just a few return types of a controller action method. In general an action method can return an instance of a any class that derives from ActionResult class.

1. ViewResult

2. JavaScriptResult

3. RedirectResult

4. ContentResult

5. JsonResult

14- What is the ‘page lifecycle’ of an ASP.NET MVC?

Following process are performed by ASP.Net MVC page:

1) App initialization

2) Routing

3) Instantiate and execute controller

4) Locate and invoke controller action

5) Instantiate and render view

15- What is the significance of NonActionAttribute?

In general, all public methods of a controller class are treated as action methods. If you want prevent this default behavior, just decorate the public method with NonActionAttribute.

16- What is the significance of ASP.NET routing?

ASP.NET MVC uses ASP.NET routing, to map incoming browser requests to controller action methods. ASP.NET Routing makes use of route table. Route table is created when your web application first starts. The route table is present in the Global.asax file.

17- How route table is created in ASP.NET MVC?

When an MVC application first starts, the Application_Start() method is called. This method, in turn, calls the RegisterRoutes() method. The RegisterRoutes() method creates the route table.

18- What are the 3 segments of the default route, that is present in an ASP.NET MVC application?

1st Segment - Controller Name

2nd Segment - Action Method Name

3rd Segment - Parameter that is passed to the action method

Example: http://google.com/search/label/MVC

Controller Name = search

Action Method Name = label

Parameter Id = MVC

19- ASP.NET MVC application, makes use of settings at 2 places for routing to work correctly. What are these 2 places?

1. Web.Config File : ASP.NET routing has to be enabled here.

2. Global.asax File : The Route table is created in the application Start event handler, of the Global.asax file.

20- What is the adavantage of using ASP.NET routing?

In an ASP.NET web application that does not make use of routing, an incoming browser request should map to a physical file. If the file does not exist, we get page not found error.

An ASP.NET web application that does make use of routing, makes use of URLs that do not have to map to specific files in a Web site. Because the URL does not have to map to a file, you can use URLs that are descriptive of the user's action and therefore are more easily understood by users.

21- What are the 3 things that are needed to specify a route?

1. URL Pattern - You can include placeholders in a URL pattern so that variable data can be passed to the request handler without requiring a query string.

2. Handler - The handler can be a physical file such as an .aspx file or a controller class.

3. Name for the Route - Name is optional.

22- Is the following route definition a valid route definition?

{controller}{action}/{id}

No, the above definition is not a valid route definition, because there is no literal value or delimiter between the placeholders. Therefore, routing cannot determine where to separate the value for the controller placeholder from the value for the action placeholder.

23- What is the use of the following default route?

{resource}.axd/{*pathInfo}

This route definition, prevent requests for the Web resource files such as WebResource.axd or ScriptResource.axd from being passed to a controller.

24- What is the difference between adding routes, to a webforms application and to an mvc application?

To add routes to a webforms application, we use MapPageRoute() method of the RouteCollection class, where as to add routes to an MVC application we use MapRoute() method.

25- How do you handle variable number of segments in a route definition?

Use a route with a catch-all parameter. An example is shown below. * is referred to as catch-all parameter.

controller/{action}/{*parametervalues}

26- What are the 2 ways of adding constraints to a route?

1. Use regular expressions

2. Use an object that implements IRouteConstraint interface

27- Give 2 examples for scenarios when routing is not applied?

1. A Physical File is Found that Matches the URL Pattern - This default behaviour can be overriden by setting the RouteExistingFiles property of the RouteCollection object to true.

2. Routing Is Explicitly Disabled for a URL Pattern - Use the RouteCollection.Ignore() method to prevent routing from handling certain requests.

28- What is the use of action filters in an MVC application?

Action Filters allow us to add pre-action and post-action behavior to controller action methods.

29- If I have multiple filters implemented, what is the order in which these filters get executed?

1. Authorization filters

2. Action filters

3. Response filters

4. Exception filters

30- What are the different types of filters, in an asp.net mvc application?

1. Authorization filters

2. Action filters

3. Result filters

4. Exception filters

31- Give an example for Authorization filters in an asp.net mvc application?

1. RequireHttpsAttribute

2. AuthorizeAttribute

32- Which filter executes first in an asp.net mvc application?

Authorization filter

33- What are the levels at which filters can be applied in an asp.net mvc application?

1. Action Method

2. Controller

3. Application

34- Is it possible to create a custom filter?

Yes

35- What filters are executed in the end?

Exception Filters

36- Is it possible to cancel filter execution?

Yes

37- What type of filter does OutputCacheAttribute class represents?

Result Filter

38- What are the 2 popular asp.net mvc view engines?

1. Razor

2. .aspx

39- What is difference between Viewbag and Viewdata in ASP.NET MVC?

The basic difference between ViewData and ViewBag is that in ViewData instead creating dynamic properties we use properties of Model to transport the Model data in View and in ViewBag we can create dynamic properties without using Model data.

40- What symbol would you use to denote, the start of a code block in razor views?

41- What symbol would you use to denote, the start of a code block in aspx views?

<%= %>

In razor syntax, what is the escape sequence character for @ symbol?

The escape sequence character for @ symbol, is another @ symbol

42- When using razor views, do you have to take any special steps to protect your asp.net mvc application from cross site scripting (XSS) attacks?

No, by default content emitted using a @ block is automatically HTML encoded to protect from cross site scripting (XSS) attacks.

43- When using aspx view engine, to have a consistent look and feel, across all pages of the application, we can make use of asp.net master pages. What is asp.net master pages equivalent, when using razor views?

To have a consistent look and feel when using razor views, we can make use of layout pages. Layout pages, reside in the shared folder, and are named as _Layout.cshtml

44- What are sections?

Layout pages, can define sections, which can then be overriden by specific views making use of the layout. Defining and overriding sections is optional.

45- What are the file extensions for razor views?

1. .cshtml - If the programming lanugaue is C#

2. .vbhtml - If the programming lanugaue is VB

46- How do you specify comments using razor syntax?

Razor syntax makes use of @* to indicate the begining of a comment and *@ to indicate the end.

47- What is Routing?

A route is a URL pattern that is mapped to a handler. The handler can be a physical file, such as an .aspx file in a Web Forms application. Routing module is responsible for mapping incoming browser requests to particular MVC controller actions.

48- Is it possible to combine ASP.NET webforms and ASP.MVC and develop a single web application?

Yes, it is possible to combine ASP.NET webforms and ASP.MVC and develop a single web application.

49. How do you avoid XSS Vulnerabilities in ASP.NET MVC?

Use the syntax in ASP.NET MVC instead of using .net framework 4.0.

_______________________________________________________________________

1. What is main objective of ASP.NET MVC 4 or What is new in MVC4 ?
Ans.

Easy Mobile web applications (ASP.NET MVC 4 complete focus on Mobile application development)
Full HTML5 support
ASP.NET MVC web application with cloud support
Working with different mobile and desktop web browsers

Description.

The main objective of ASP.NET MVC 4 is making to develop mobile web applications easily.Other than mobile web applications It’s focus is also on better HTML5 support and making ASP.NET MVC web application cloud ready.

By using new features of ASP.NET MVC 4 you can develop web applications that can work well across different desktop web browsers and mobile devices.

2. What is Web API ‘s in Asp.Net MVC 4 ?
Ans.

Web API is a new framework for consuming & building HTTP Services.
Web API supports wide range of clients including different browsers and mobile devices.
It is very good platform for developing RESTful services since it talk’s about HTTP.

3. What is the use of web API ? Why Web API needed, If you have already RESTful services using WCF ?

Ans. Yes, we can still develop the RESTful services with WCF, but there are two main reasons that prompt users to use Web API instead of RESTful services.

ASP.NET Web API is included in ASP.NET MVC which obviously increases TDD (Test Data Driven) approach in the development of RESTful services.

For developing RESTful services in WCF you still needs lot of config settings, URI templates, contract’s & endpoints which developing RESTful services using web API is simple.

4. What are the new enhancements done in default project template of ASP.NET MVC 4?Ans.

Adaptive rendering for Nice Look & Feel
Modern Looking for Mobile & Desktop browser

The new enhanced default project template came up with modern looking. Along with some cosmetic enhancements, it also employs new adaptive rendering to look nice in both desktop and mobile browsers without need of any kind of additional customization.

5. Why we need a separate mobile project template, while we can render our web application in mobile (What’s new in MVC 4 Mobile template) ?

Ans.

Smart Phones & tablets touch got smart by using new jQuery.Mobile.MVC NuGet pacage.

The mobile project template touch optimized UI by using jQuery.Mobile.MVC NuGet Package for tablets and smart phones.

6. What is the use of Display Modes?
Ans.

View can be changed automatically based on browser(For mobile and desktop browser’s)

Display Modes is newly added feature in ASP.NET MVC 4. Views selected automatically by application depending on the browser. Example: If a desktop browser requests login page of an application it will return Views\Account\Login.cshtml view & if a mobile browser requests home page it will return Views\Account\Login.mobile.cshtml view.

7. What are the main features of ASP.NET MVC 4 used by ASP.NET Web API?

Ans.

Routing changes: ASP.NET Web API uses same convention for config mapping that ASP.NET MVC provides.
Model Binding & Validation: ASP.NET Web API uses same model binding functionality, but HTTP specific context related operations only.
Filters: The ASP.NET Web API uses most of built-in filters from MVC.
Unit Testing: Now Unit testing based on MVC, strongly unit testable.

8. What are Bundling & Minification features in ASP.NET MVC 4?

Ans. Bundling & Minification reduces number of HTTP requests. Bundling & Minification combines individual files into single. Bundled file for CSS & scripts and then it reduce’s overall size by minifying the contents of the bundle.

9 . What are the difference between asynchronous controller implementation b/w ASP.NET MVC 3 & ASP.NET MVC 4? Can you explain in detail?

Ans. There is major difference is on implementation mechanism between ASP.NET MVC 3 and ASP.NET MVC 4.

In ASP.NET MVC 3, to implement async controller or methods we need to derive controller from AsyncController rather than from normal plain Controller class. We need to create 2 action methods rather than one. First with suffix ’Async’ keyword & second with ‘Completed’ suffix.

In ASP.NET MVC 4 you need not to declare 2 action method. One can serve the purpouse. MVC 4 using .Net Framework 4.5 support for asynchronous communication.

10. Is MVC 4 supporting Windows Azure SDK (Software Development Kit) ?

Ans. Yes, MVC 4 is supporting Windows Azure SDK version 1.6 or higher.

_____________________________________________________________________

1. What is main focus of ASP.NET MVC 4?
Ans. The main focus of ASP.NET MVC 4 is making it easier to develop mobile web applications. Other than mobile web applications it’s focus is also on better HTML5 support and making ASP.NET MVC web application cloud ready. Using new features of ASP.NET MVC 4 you can develop web applications that can work well across different mobile devices and desktop web browsers.

2. What is ASP.NET Web API?
Ans. ASP.NET Web API is a framework for building and consuming HTTP Services. It supports wide range of clients including browsers and mobile devices. It is a great platform for developing RESTful services since it talks HTTP.

3. You can also develop RESTful services using WCF, then why this new framework Web API?
Ans. Yes we can still develop RESTful services with WCF, but there are two things that prompt users to use ASP.NET Web API over WCF for development of RESTful services. First one is ASP.NET Web API is included in ASP.NET MVC which obviously increases TDD approach in the development of RESTful services. Second one is for developing RESTful services in WCF you still needs lot of configurations, URI templates, contracts and endpoints which developing RESTful services using ASP.NET Web API is simple.

4. What are the enhancements done in default project template of ASP.NET MVC 4?
Ans. The enhanced default project template is modern-looking. Along with cosmetic enhancements, it also employs adaptive rendering to look nice in both desktop and mobile browsers without need of any kind of additional customization.

5. Why separate mobile project template while you can render your web application in mobile without additional customization?
Ans. The mobile project template touch-optimized UI using jQuery.Mobile.MVC NuGet Package for smart phones and tablets.

6. What is Display Modes?
Ans. Display Modes is new feature provided in ASP.NET MVC 4. It lets an application select views depending on the browser which is making request. For example, if a desktop browser requests home page of an application it will return Views\Home\Index.cshtml view and if a mobile browser requests home page it will return Views\Home\Index.mobile.cshtml view.

7. Does ASP.NET MVC 4 supports Windows Azure SDK?
Ans. Yes, ASP.NET MVC 4 supports Windows Azure SDK version 1.6 or higher.

8. What is Bundling and Minification feature provided in ASP.NET MVC 4?
Ans. It reduces number of HTTP requests that a web page needs to make. Bundling and Minification combines individual files into single, bundled file for scripts and CSS and then reduce the overall size by minifying the contents of the bundle.

9. While developing application using ASP.NET MVC 4, I want to provide authentication using popular sites like Facebook or twitter into my web application, is it possible in ASP.NET MVC 4?
Ans. Yes, using DotNetOpenAuth library we can provide authentication using OAuth or OpenID providers. In ASP.NET MVC 4 Internet project template includes this library.

10. What’s the difference between Empty MVC Project template in ASP.NET MVC 3 and ASP.NET MVC 4?
Ans. The ASP.NET MVC 4 Empty project template is really empty. It does not contain any css and js files as compared to previous Empty project template, which contains all these files.

11. What are the main features of ASP.NET MVC used by ASP.NET Web API?
Ans.
Routing: ASP.NET Web API uses same convention for configuration mapping that ASP.NET MVC provides.
Model Binding and Validation: ASP.NET Web API uses same model binding functionality, but tailored to HTTP specific context related operations only.
Filters: The ASP.NET Web API uses lots of filters built-in MVC.
Unit Testing: Now it’s based on MVC, truly unit testable.

12. If I want to create resource oriented services that can use full features of HTTP like cache control for browsers, use URI templates to include Task URIs in your responses, versioning and concurrancy using ETags, pass various content types such as images, documents, HTML pages etc. then which is preferred for development of services, WCF or Web API?
Ans. In such scenario Web API would be preferred choice. Using Web APIs we can develop services which utilizes full features of HTTP.

13. Suppose I want to develop services which supports special scenarios like one way messaging, duplex communication, message queues, ete then which is the best way to develop services, WCF or Web API?
Ans. In this scenario WCF suits the requirement. WCF provides all kine of messaging facility.

14. Now, if I want to create services which are exposed over various transport channels like TCP, Named Pipe or even UDP. I also want the support of HTTP transport channel when other transport channels are unavailable then which is the preferred way, WCF or Web API and why?
Ans. For such scenario WCF is preferred way for development of services because WCF support almost all kind of transport mechanism and we need to expose SOAP-based and WebHTTP-based bindings.

15. What is the difference between asynchronous controller implementation between ASP.NET MVC 3 and ASP.NET MVC 4? Can you explain in detail?
Ans. There is large difference between the working and implementation mechanism between ASP.NET MVC 3 and ASP.NET MVC 4.

In ASP.NET MVC 3, to implement asynchronous controller/methods you need to derive controller from AsyncController rather than from plain Controller class. You need to create two action methods rather than one. Fist with suffix “Async” keyword and second with “Completed” suffix. The method which initiated asynchronous process must end with “Async” and the method which is invoked when the asynchronous process finishes must end with “Completed”. Following is example showing the same.

//Synchronous Implementation

public class SynchronousTestController : Controller

{

    public ActionResult Index()

    {

        method1();

        method2();

        return View();

    }

}

//Asynchronous Implementation in ASP.NET MVC 3

public class AsynchronousTestController : AsyncController

{

    public void IndexAsync()

    {

        method1();

        method2();

    }

    public ActionResult IndexCompleted()

    {

        return View("Index");

    }

}

The ASP.NET MVC 4 Controller class in combination .NET 4.5 enables you to write asynchronous action methods that return an object of type Task. The .NET Framework 4 introduced an asynchronous programming concept referred to as a Task and ASP.NET MVC 4 supports Task. The .NET Framework 4.5 builds on this asynchronous support with the await and async keywords that make working with Task objects much less complex than previous asynchronous approaches. The await keyword is syntactical shorthand for indicating that a piece of code should asynchronously wait on some other piece of code. The async keyword represents a hint that you can use to mark methods as task-based asynchronous methods. To implement asynchronous action method in ASP.NET MVC 4 we do no need to derive our controller class from AsyncController, async and await in cooperation with Task will do the magic. To mark the action method asynchronous use async in method signature. To wait for the other method to finish use await and to call multiple parallel methods use Task. The asynchronous method will return Task instead of plain ActionResult.

public class AsyncronousTestController : Controller

{

    public async Task<ActionResult> IndexAsync()

    {

        //if single method

        //await method();

        //if multiple methods

        await Task.WhenAll(method1(), method2());

        return View("Index");

    }

}

Here the await keyword does not block the thread execution until the task is complete. It signs up the rest of the method as a callback on the task, and immediately returns. When the awaited task eventually completes, it will invoke that callback and thus resume the execution of the method right where it left off.

16. Can you tell us some guidelines for when to use synchronous and when to use asynchronous approach?
Ans. In following situations synchronous approach is more suited.

The operations are simple or short-running.
Simplicity is more important than efficiency.
The operations are primarily CPU operations instead of operations that involve extensive disk or network overhead. Using asynchronous action methods on CPU-bound operations provides no benefits and results in more overhead.

For asynchronous approach some of the guidelines are

You’re calling services that can be consumed through asynchronous methods, and you’re using .NET 4.5 or higher.
The operations are network-bound or I/O-bound instead of CPU-bound.
Parallelism is more important than simplicity of code.
You want to provide a mechanism that lets users cancel a long-running request.
When the benefit of switching threads out weights the cost of the context switch. In general, you should make a method asynchronous if the synchronous method waits on the ASP.NET request thread while doing no work. By making the call asynchronous, the ASP.NET request thread is not stalled doing no work while it waits for the web service request to complete.
Testing shows that the blocking operations are a bottleneck in site performance and that IIS can service more requests by using asynchronous methods for these blocking calls.

17. Which latest version of Entity Framework is included by ASP.NET MVC 4? What is the advantage of it?
Ans. ASP.NET MVC 4 is included Entity Framework 5. The main advantage of Entity Framework 5 is it’s new feature called database migration. It enables you to easily evolve your database schema using a code-focused migration while preserving the data in the database.

18. What is ASP.NET MVC 4 recipe? Can you explore something on recipes?
Ans. In technical language ASP.NET MVC 4 recipe is nothing but a dialog box that is delivered via NuGet with associated UI and code used to automate specific task. It’s like GUI for NuGet Package Manager. Recipes are set of assemblies which are loaded dynamically by Managed Extensibility Framework (MEF). MEF provides plugin model for applications. The main use of recipes are to automate development task, tasks that are encapsulated into recipes and used over and over again. For example, adding ajax grid to view or manipulating multiple areas of the application can be automated using ASP.NET MVC 4 recipes.

18. What are the provisions for real time communication in ASP.NET MVC 4?
Ans. ASP.NET MVC 4 supports WebSockets along with the new open source framework SignalR which allows to set up real time multi-user communication through open TCP sockets.

19. What is the enhancement provided related to custom controller in ASP.NET MVC 4?
Ans. In ASP.NET MVC 4 you can place custom controller to custom locations. In ASP.NET MVC 3 you can only place custom controllers inside the Controllers folder.

What is MVC?

MVC is a framework methodology that divides an application’s implementation into three component roles: models, views, and controllers.

“Models” in a MVC based application are the components of the application that are responsible for maintaining state. Often this state is persisted inside a database (for example: we might have a Product class that is used to represent order data from the Products table inside SQL).
“Views” in a MVC based application are the components responsible for displaying the application’s user interface. Typically this UI is created off of the model data (for example: we might create an Product “Edit” view that surfaces textboxes, dropdowns and checkboxes based on the current state of a Product object).
“Controllers” in a MVC based application are the components responsible for handling end user interaction, manipulating the model, and ultimately choosing a view to render to display UI. In a MVC application the view is only about displaying information – it is the controller that handles and responds to user input and interaction.

Which are the advantages of using MVC Framework?

MVC is one of the most used architecture pattern in ASP.NET and this is one of those ASP.NET interview question to test that do you really understand the importance of model view controller.
1. It provides a clean separation of concerns between UI and model.
2. UI can be unit test thus automating UI testing.
3. Better reuse of views and model. You can have multiple views which can point to the same model and also vice versa.
4. Code is better organized.

What is Razor View Engine?

What is namespace of asp.net mvc?

ASP.NET MVC namespaces and classes are located in the System.Web.Mvc assembly.

System.Web.Mvc namespace
Contains classes and interfaces that support the MVC pattern for ASP.NET Web applications. This namespace includes classes that represent controllers, controller factories, action results, views, partial views, and model binders.

System.Web.Mvc.Ajax namespace
Contains classes that support Ajax scripts in an ASP.NET MVC application. The namespace includes support for Ajax scripts and Ajax option settings.

System.Web.Mvc.Async namespace
Contains classes and interfaces that support asynchronous actions in an ASP.NET MVC application

System.Web.Mvc.Html namespace
Contains classes that help render HTML controls in an MVC application. The namespace includes classes that support forms, input controls, links, partial views, and validation.

How to identify AJAX request with C# in MVC.NET?

The solution is in depended from MVC.NET framework and universal across server-side technologies. Most modern AJAX applications utilize XmlHTTPRequest to send async request to the server. Such requests will have distinct request header:

X-Requested-With = XMLHTTPREQUEST

MVC.NET provides helper function to check for ajax requests which internally inspects X-Requested-With request header to set IsAjax flag.

HelperPage.IsAjax Property
Gets a value that indicates whether Ajax is being used during the request of the Web page.

Namespace: System.Web.WebPages
Assembly: System.Web.WebPages.dll

However, same can be achieved by checking requests header directly:

Request["X-Requested-With"] == “XmlHttpRequest”

What is Repository Pattern in ASP.NET MVC?

Repository pattern is useful for decoupling entity operations form presentation, which allows easy mocking and unit testing.

“The Repository will delegate to the appropriate infrastructure services to get the job done. Encapsulating in the mechanisms of storage, retrieval and query is the most basic feature of a Repository implementation”

“Most common queries should also be hard coded to the Repositories as methods.”

Which MVC.NET to implement repository pattern Controller would have 2 constructors on parameterless for framework to call, and the second one which takes repository as an input:

class myController: Controller

{

    private IMyRepository repository;

    // overloaded constructor

    public myController(IMyRepository repository)  

    {

        this.repository = repository;

    }

    // default constructor for framework to call

    public myController() 

    {

        //concreate implementation

        myController(new someRepository()); 

    }

...

    public ActionResult Load()

    {

        // loading data from repository

        var myData = repository.Load(); 

    }

}

What is difference between MVC(Model-View-Controller) and MVP(Model-View-Presenter)?

The main difference between the two is how the manager (controller/presenter) sits in the overall architecture.

All requests goes first to the ControllerMVC pattern puts the controller as the main ‘guy’ in charge for running the show. All application request comes through straight to the controller, and it will decide what to do with the request.

Giving this level of authority to the controller isn’t an easy task in most cases. Users interaction in an application happen most of the time on the View.

Thus to adopt MVC pattern in a web application, for example, the url need to become a way of instantiating a specific controller, rather than ‘simply’ finding the right View (webform/ html page) to render out. Every requests need to trigger the instantiation of a controller which will eventually produce a response to the user.

This is the reason why it’s alot more difficult to implement pure MVC using Asp.Net Webform. The Url routing system in Asp.Net webform by default is tied in to the server filesystem or IIS virtual directory structure. Each of these aspx files are essentially Views which will always get called and instantiated first before any other classes in the project. (Of course I’m overgeneralizing here. Classes like IHttpModule, IHttpHandler and Global.asax would be instantiated first before the aspx web form pages).

MVP (Supervising Controller) on the other hand, doesn’t mind for the View to take on a bigger role. View is the first object instantiated in the execution pipeline, which then responsible for passing any events that happens on itself to the Presenter.

The presenter then fetch the Models, and pass it back to the view for rendering.

For more detailed answer see my post MVC Vs MVP.

What is the ‘page lifecycle’ of an ASP.NET MVC?

Following process are performed by ASP.Net MVC page:
1) App initialization
2) Routing
3) Instantiate and execute controller
4) Locate and invoke controller action
5) Instantiate and render view

How to call javascript function on the change of Dropdown List in ASP.NET MVC?

Create a java-script function:

<script type="text/javascript">

            function selectedIndexChanged() {

            }

</script>

Call the function:

<%:Html.DropDownListFor(x => x.SelectedProduct, 

new SelectList(Model.Products, "Value", "Text"),

"Please Select a product", new { id = "dropDown1", 

onchange="selectedIndexChanged()" })%>

How route table is created in ASP.NET MVC?

When an MVC application first starts, the Application_Start() method is called. This method, in turn, calls the RegisterRoutes() method. The RegisterRoutes() method creates the route table.

How do you avoid XSS Vulnerabilities in ASP.NET MVC?

Use the syntax <%: %> in ASP.NET MVC instead of using <%= %> .net framework 4.0.
You can also use Anti-XSS library as a default encoding engine for ASP.NET MVC.

Explain how to access Viewstate values of this page in the next page?

PreviousPage property is set to the page property of the nest page to access the viewstate value of the page in the next page.

Page poster = this.PreviousPage;

Once that is done, a control can be found from the previous page and its state can be read.

Label posterLabel = poster.findControl("myLabel");

 string lbl = posterLabel.Text;

How to create dynamic property with the help of viewbag in ASP.NET MVC?

You can directly assign some key name with syntax ViewBag.[KeyName]=[SomeValue] and value using equal to operator.
For example, you need to assign list of countries to the dynamic Countries property of ViewBag.

List<string> countries = new List<string>();

countries.Add("Australia");

countries.Add("UK");

ViewBag.Countries = countries; 

//Countries is dynamic property associated with ViewBag

What is difference between Viewbag and Viewdata in ASP.NET MVC?

What is Routing?

_____________________________________________________________________

MVC3 Interview Questions and Answers Introduction:

What is MVC?

MVC is a framework pattern that splits an application’s implementation logic into

three component roles: models, views, and controllers.

Model: The business entity on which the overall application operates. Many applications use a persistent storage mechanism (such as a database) to store data. MVC does not specifically mention the data access layer because it is understood to be encapsulated by the Model.
View: The user interface that renders the Model into a form of interaction.
Controller: Handles a request from a View and updates the Model that results in a change of the Model's state.

To implement MVC in .NET we need mainly three classes (View, Controller and the Model).

Explain MVC Architecture?

The architecture is self explanatory. The browser (as usual) sends a request to IIS, IIS searches for the route defined in MVC application and passes the request to the controller as per route, the controller communicates with the model and passes the populated model (entity) to View (front end), Views are populated with model properties, and are rendered on the browser, passing the response to browser through IIS via controllers which invoked the particular View.

What are the new features of MVC2?

ASP.NET MVC 2 was released in March 2010. Its main features are:

· Introduction of UI helpers with automatic scaffolding with customizable templates.

· Attribute-based model validation on both client and server.

· Strongly typed HTML helpers.

· Improved Visual Studio tooling

· There were also lots of API enhancements and “pro” features, based on feedback from developers building a variety of applications on ASP.NET MVC 1, such as:

Ø Support for partitioning large applications into areas.

Ø Asynchronous controllers support.

Ø Support for rendering subsections of a page/site using Html.RenderAction.

Ø Lots of new helper functions, utilities, and API enhancements.

What are the new features of MVC3?

ASP.NET MVC 3 shipped just 10 months after MVC 2 in Jan 2011.Some of the top features in MVC 3 included:

· The Razor view engine.

· Support for .NET 4 Data Annotations.

· Improved model validation

· Greater control and flexibility with support for dependency resolution and global action filters.

· Better JavaScript support with unobtrusive JavaScript, jQuery Validation, and JSON binding.

· Use of NuGet to deliver software and manage dependencies throughout the platform.

What are the new features of MVC4?

Following are the top features of MVC4:

· ASP.NET Web API.

· Enhancements to default project templates.

· Mobile project template using jQuery Mobile.

· Display Modes.

· Task support for Asynchronous Controllers.

· Bundling and minification.

Explain “page lifecycle” of an ASP.NET MVC?

Following process are performed by ASP.Net MVC page:

1) App initialization

2) Routing

3) Instantiate and execute controller

4) Locate and invoke controller action

5) Instantiate and render view

Advantages of MVC Framework?

1. Provides a clean separation of concerns between UI (Presentation layer), model (Transfer objects/Domain Objects/Entities) and Business Logic (Controller).

2. Easy to UNIT Test.

3. Improved reusability of views/model. One can have multiple views which can point to

same model and vice versa.

4. Improved structuring of the code.

What do you mean by Separation of Concerns?

As per Wikipedia 'the process of breaking a computer program into distinct features that overlap in functionality as little as possible'. MVC design pattern aims to separate content from presentation and data-processing from content.

Where do we see Separation of Concerns in MVC?

Between the data-processing (Model) and the rest of the application.

When we talk about Views and Controllers, their ownership itself explains separation. The views are just the presentation form of an application, it does not have to know specifically about the requests coming from controller. The Model is independent of View and Controllers, it only holds business entities that can be passed to any View by the controller as required for exposing them to the end user. The controller is independent of Views and Models, its sole purpose is to handle requests and pass it on as per the routes defined and as per the need of rendering views. Thus our business entities (model), business logic (controllers) and presentation logic (views) lie in logical/physical layers independent of each other.

What is Razor View Engine?

Razor is the first major update to render HTML in MVC3. Razor was designed specifically as a view engine syntax. It has one main focus: code-focused templating for HTML generation. Here’s how that same markup would be generated using Razor:

@model MvcMusicStore.Models.Genre

@{ViewBag.Title = "Browse Albums";}

<h3><em>@Model.Name</em> Albums</h3>

@foreach (var album in Model.Albums)

{

<li>

<span>@album.Title</span>

</a>

</li>

}

</ul>

</div>

The Razor syntax is easier to type, and easier to read. Razor doesn’t have the XML-like heavy syntax.

of the Web Forms view engine.

What is Unobtrusive JavaScript?

Unobtrusive JavaScript is a general term that conveys a general philosophy, similar to the term

REST (Representational State Transfer). The high-level description is that unobtrusive JavaScript doesn’t intermix JavaScript code in your page markup. For example, rather than hooking in via event attributes like onclick and onsubmit, the unobtrusive JavaScript attaches to elements by their ID or class, often based on the presence of other attributes (such as HTML5 data- attributes).

It’s got semantic meaning, and all of it — the tag structure, element attributes, and so on — should have a precise meaning. Strewing JavaScript gunk across the page to facilitate interaction (I’m looking at you, __doPostBack!) harms the content of the document.

What is JSON Binding?

MVC 3 included JavaScript Object Notation (JSON) binding support via the new

JsonValueProviderFactory, enabling the action methods to accept and model-bind data in JSON format. This is especially useful in advanced Ajax scenarios like client templates and data binding that need to post data back to the server.

What is Dependency Resolution?

MVC 3 introduced a new concept called a dependency resolver, which greatly simplified the use of dependency injection in your applications. This made it easier to decouple application components, making them more configurable and easier to test.

Support was added for the following scenarios:

· Controllers (registering and injecting controller factories, injecting controllers)

· Views (registering and injecting view engines, injecting dependencies into view pages)

· Action fi lters (locating and injecting fi lters)

· Model binders (registering and injecting)

· Model validation providers (registering and injecting)

· Model metadata providers (registering and injecting)

· Value providers (registering and injecting)

What are Display Modes in MVC4?

Display modes use a convention-based approach to allow selecting different views based on the browser making the request. The default view engine fi rst looks for views with names ending with .Mobile.cshtml when the browser’s user agent indicates a known mobile device. For example, if we have a generic view titled Index.cshtml and a mobile view titled Index.Mobile.cshtml, MVC 4 will automatically use the mobile view when viewed in a mobile browser.

Additionally, we can register your own custom device modes that will be based on your own custom criteria — all in just one code statement. For example, to register a WinPhone device mode that would serve views ending with .WinPhone.cshtml to Windows Phone devices, you’d use the following code in the Application_Start method of your Global.asax:

DisplayModeProvider.Instance.Modes.Insert(0, new DefaultDisplayMode("WinPhone")

{

ContextCondition = (context => context.GetOverriddenUserAgent().IndexOf

("Windows Phone OS", StringComparison.OrdinalIgnoreCase) >= 0)

});

What is AuthConfig.cs in MVC4?

AuthConfig.cs is used to configure security settings, including sites for OAuth login.

What is BundleConfig.cs in MVC4?

BundleConfig.cs in MVC4 is used to register bundles used by the bundling and minification

system. Several bundles are added by default, including jQuery, jQueryUI, jQuery validation, Modernizr, and default CSS references.

What is FilterConfig.cs in MVC4?

This is used to register global MVC filters. The only filter registered by default is the HandleErrorAttribute, but this is a great place to put other filter registrations.

What is RouteConfig.cs in MVC4?

RouteConfig.cs holds the granddaddy of the MVC config statements, Route configuration.

What is WebApiConfig.cs in MVC4?

Used to register Web API routes, as well as set any additional Web API configuration settings.

What’s new in adding controller in MVC4 application?

Previously(in MVC3 and MVC2), the Visual Studio Add Controller menu item only displayed when we right-clicked on the Controllers folder. However, the use of the Controllers folder was purely for organization. (MVC will recognize any class that implements the IController interface as a Controller, regardless of its location in your application.) The MVC 4 Visual Studio tooling has been modified to display the Add Controller menu item for any folder in your MVC project. This allows us to organize your controllers however you would like, perhaps separating them into logical groups or separating MVC and Web API controllers.

What are the software requirements of ASP.NET MVC4 application?

MVC 4 runs on the following Windows client operating systems:

ü Windows XP

ü Windows Vista

ü Windows 7

ü Windows 8

It runs on the following server operating systems:

ü Windows Server 2003

ü Windows Server 2008

ü Windows Server 2008 R2

MVC 4 development tooling is included with Visual Studio 2012 and can be installed on Visual

Studio 2010 SP1/Visual Web Developer 2010 Express SP1.

What are the various types of Application Templates used to create an MVC application?

The various templates are as follows,

1. The Internet Application template: This contains the beginnings of an MVC web

application — enough so that you can run the application immediately after creating it

and see a few pages. This template also includes some basic account management functions which run against the ASP.NET Membership .

2. The Intranet Application template: The Intranet Application template was added as part of

the ASP.NET MVC 3 Tools Update. It is similar to the Internet Application template,but the account management functions run against Windows accounts rather than the ASP.NET Membership system.

3. The Basic template: This template is pretty minimal. It still has the basic folders, CSS, and

MVC application infrastructure in place, but no more. Running an application created using

the Empty template just gives you an error message.

Why use Basic template? The Basic template is intended for experienced MVC developers

who want to set up and configure things exactly how they want them.

4.The Empty template: The Basic template used to be called the Empty template, but developers complained that it wasn’t quite empty enough. With MVC 4, the previous Empty

template was renamed Basic, and the new Empty template is about as empty as we can get.

It has the assemblies and basic folder structure in place, but that’s about it.

5. The Mobile Application template: The Mobile Application template is preconfigured with jQuery Mobile to jump-start creating a mobile only website. It includes mobile visual themes, a touch-optimized UI, and support for Ajax navigation.

6. The Web API template: ASP.NET Web API is a framework for creating HTTP services.

The Web API template is similar to the Internet Application template but is streamlined for Web API development. For instance, there is no user account management functionality, as Web API account management is often signify-cantly different from standard MVC account management. Web API functionality is also available in the other MVC project templates, and even in non-MVC project types.

What are the default Top level directories created when adding MVC4 application?

Default Top level Directories are:

DIRECTORY PURPOSE

/Controllers To put Controller classes that handle URL requests

/Models To put classes that represent and manipulate data and business objects

/Views To put UI template files that are responsible for rendering output like HTML.

/Scripts To put JavaScript library files and scripts (.js)

/Images To put images used in your site

/Content To put CSS and other site content, other than scripts and images

/Filters To put filter code.

/App_Data To store data files you want to read/write

/App_Start To put configuration code for features like Routing, Bundling, Web API.

What is namespace of asp.net mvc?

ASP.NET MVC namespaces as well as classes are located in assembly System.Web.Mvc.

Note: Some of the content has been taken from various books/articles.

What is System.Web.Mvc namespace?

This namespace contains classes and interfaces that support the MVC pattern for ASP.NET Web applications. This namespace includes classes that represent controllers, controller

factories, action results, views, partial views, and model binders.

What is System.Web.Mvc.Ajax namespace?

System.Web.Mvc.Ajax namespace contains classes that supports Ajax scripting in an ASP.NET MVC application. The namespace includes support for Ajax scripts and Ajax option settings as well.

What is System.Web.Mvc.Async namespace?

System.Web.Mvc.Async namespace contains classes and interfaces that support asynchronous actions in an ASP.NET MVC application.

What is System.Web.Mvc.Html namespace?

System.Web.Mvc.Html namespace contains classes that help render HTML controls in an MVC application. This namespace includes classes that support forms, input controls, links, partial views, and validation.

What is ViewData, ViewBag and TempData?

MVC provides us ViewData, ViewBag and TempData for passing data from controller, view and in next requests as well. ViewData and ViewBag are similar to some extent but TempData performs additional roles.

What are the roles and similarities between ViewData and ViewBag?

Maintains data when move from controller to view.
Passes data from controller to respective view.
Their value becomes null when any redirection occurs, because their role is to provide a way to communicate between controllers and views. It’s a communication mechanism within the server call.

What are the differences between ViewData and ViewBag?(taken from a blog)

ViewData is a dictionary of objects that is derived from ViewDataDictionary class and accessible using strings as keys.
ViewBag is a dynamic property that takes advantage of the new dynamic features in C# 4.0.
ViewData requires typecasting for complex data type and check for null values to avoid error.
ViewBag doesn’t require typecasting for complex data type.

NOTE Although there might not be a technical advantage to choosing one format over the other, there are some critical differences to be aware of between the two syntaxes.

One obvious difference is that ViewBag works only when the key being accessed is a valid C# identifier. For example, if you place a value in ViewData["KeyWith Spaces"], you can’t access that value using ViewBag because the codewon’t compile.

Another key issue to be aware of is that dynamic values cannot be passed in as parameters to extension methods. The C# compiler must know the real type of every parameter at compile time in order for it to choose the correct extension method.

If any parameter is dynamic, compilation will fail. For example, this code will always fail: @Html.TextBox("name", ViewBag.Name). To work around this,either use ViewData["Name"] or cast the value to a specifi c type: (string) ViewBag.Name.

What is TempData?

TempData is a dictionary derived from the TempDataDictionary class and stored in short lives session. It is a string key and object value.

It keep the information for the time of an HTTP Request. This means only from one page to another. It helps to maintain data when we move from one controller to another controller or from one action to other action. In other words, when we redirect Tempdata helps to maintain data between those redirects. It internally uses session variables. Temp data use during the current and subsequent request only means it is use when we are sure that next request will be redirecting to next view. It requires typecasting for complex data type and check for null values to avoid error. Generally it is used to store only one time messages like error messages, validation messages.

How can you define a dynamic property with the help of viewbag in ASP.NET MVC?

Assign a key name with syntax,

ViewBag.[Key]=[ Value] and value using equal to operator.

For example, you need to assign list of students to the dynamic Students property

of ViewBag.

List<string> students = new List<string>();

countries.Add("Akhil");

countries.Add("Ekta");

ViewBag.Students = students;

//Students is a dynamic property associated with ViewBag.

Note: Some of the content has been taken from various books/articles.

What is ViewModel(taken from stackoverflow)?

accepted

A view model represents data that you want to have displayed on your view/page.

Lets say that you have an Employee class that represents your employee domain model and it contains the following 4 properties:

public class Employee : IEntity

{

public int Id { get; set; } // Employee's unique identifier

public string FirstName { get; set; } // Employee's first name

public string LastName { get; set; } // Employee's last name

public DateTime DateCreated { get; set; } // Date when employee was created

}

View models differ from domain models in that view models only contain the data (represented by properties) that you want to use on your view. For example, lets say that you want to add a new employee record, your view model might look like this:

public class CreateEmployeeViewModel

{

public string FirstName { get; set; }

public string LastName { get; set; }

}

As you can see it only contains 2 of the properties of the employee domain model. Why is this you may ask? Id might not be set from the view, it might be auto generated by the Employee table. AndDateCreated might also be set in the stored procedure or in the service layer of your application. So Id and DateCreated is not need in the view model.

When loading the view/page, the create action method in your employee controller will create an instance of this view model, populate any fields if required, and then pass this view model to the view:

public class EmployeeController : Controller

{

private readonly IEmployeeService employeeService;

public EmployeeController(IEmployeeService employeeService)

{

this.employeeService = employeeService;

}

public ActionResult Create()

{

CreateEmployeeViewModel viewModel = new CreateEmployeeViewModel();

return View(viewModel);

}

public ActionResult Create(CreateEmployeeViewModel viewModel)

{

// Do what ever needs to be done before adding the employee to the database

}

Your view might look like this (assuming you are using ASP.NET MVC3 and razor):

@model MyProject.Web.ViewModels.ProductCreateViewModel

<table>

<tr>

<td><b>First Name:</b></td>

<td>@Html.TextBoxFor(x => x.FirstName, new { maxlength = "50", size = "50" })

@Html.ValidationMessageFor(x => x.FirstName)

</td>

</tr>

<tr>

<td>@Html.TextBoxFor(x => x.LastName, new { maxlength = "50", size = "50" })

@Html.ValidationMessageFor(x => x.LastName)

</td>

</tr>

</table>

Validation would thus be done only on FirstName and LastName. Using Fluent Validation you might have validation like this:

public class CreateEmployeeViewModelValidator : AbstractValidator<CreateEmployeeViewModel>

{

public CreateEmployeeViewModelValidator()

{

RuleFor(x => x.FirstName)

.NotEmpty()

.WithMessage("First name required")

.Length(1, 50)

.WithMessage("First name must not be greater than 50 characters");

RuleFor(x => x.LastName)

.NotEmpty()

.WithMessage("Last name required")

.Length(1, 50)

.WithMessage("Last name must not be greater than 50 characters");

}

The key thing to remember is that the view model only represents the data that you want use. You can imagine all the uneccessary code and validation if you have a domain model with 30 properties and you only want to update a single value. Given this scenario you would only have this one value/property in the view model and not the whole domain object.

How do you check for AJAX request with C# in MVC.NET?

The solution is independed of MVC.NET framework and is global across server side

technologies. Most modern AJAX applications utilize XmlHTTPRequest to send

async request to the server. Such requests will have distinct request header:

X-Requested-With = XMLHTTPREQUEST

MVC.NET provides helper function to check for ajax requests which internally inspects

X-Requested-With request header to set IsAjax flag.

What are Scaffold template?

These templates use the Visual Studio T4 templating system to generate a view based on the model type selected. Scaffolding in ASP.NET MVC can generate the boilerplate code we need for create, read, update,and delete (CRUD) functionality in an application. The scaffolding templates can examine the type definition for, and then generate a controller and the controller’s associated views. The scaffolding knows how to name controllers, how to name views, what code needs to go in each component, and where to place all these pieces in the project for the application to work.

What are the types of Scaffolding Templates?

Various types are as follows,

SCAFFOLD DESCRIPTION

Empty Creates empty view. Only the model type is specified using the model syntax.

Create Creates a view with a form for creating new instances of the model.

Generates a label and input field for each property of the model type.

Delete Creates a view with a form for deleting existing instances of the model.

Displays a label and the current value for each property of the model.

Details Creates a view that displays a label and the value for each property of the

model type.

Edit Creates a view with a form for editing existing instances of the model.

Generates a label and input fi eld for each property of the model type.

List Creates a view with a table of model instances. Generates a column

for each property of the model type. Make sure to pass an IEnumerable<YourModelType> to this view from your action method.

The view also contains links to actions for performing the create/edit/delete operations.

Show an example of difference in syntax in Razor and WebForm View?

Razor <span>@model.Message</span>

Web Forms <span><%: model.Message %></span>

Code expressions in Razor are always HTML encoded. This Web Forms syntax also automatically HTML encodes the value.

What are Code Blocks in Views?

Unlike code expressions, which are evaluated and outputted to the response, blocks of code are simply sections of code that are executed. They are useful for declaring variables that we may need to use later.

Razor

int x = 123;

string y = ˝because.˝;

}

Web Forms

int x = 123;

string y = "because.";

What is HelperPage.IsAjax Property?

HelperPage.IsAjax gets a value that indicates whether Ajax is being used during the request of the Web page.

Namespace: System.Web.WebPages

Assembly: System.Web.WebPages.dll

However, same can be achieved by checking requests header directly:

Request["X-Requested-With"] == “XmlHttpRequest”.

Explain combining text and markup in Views with the help of an example?

This example shows what intermixing text and markup looks like using Razor as compared to Web Forms:

Razor

@foreach (var item in items) {

}

Web Forms

<% foreach (var item in items) { %>

<% } %>

Explain Repository Pattern in ASP.NET MVC?

In simple terms, a repository basically works as a mediator between our business logic layer and our data access layer of the application. Sometimes, it would be troublesome to expose the data access mechanism directly to business logic layer, it may result in redundant code for accessing data for similar entities or it may result in a code that is hard to test or understand. To overcome these kinds of issues, and to write an Interface driven and test driven code to access data, we use Repository Pattern. The repository makes queries to the data source for the data, thereafter maps the data from the data source to a business entity/domain object, finally and persists the changes in the business entity to the data source. According to MSDN, a repository separates the business logic from the interactions with the underlying data source or Web service. The separation between the data and business tiers has three benefits:

It centralizes the data logic or Web service access logic.
It provides a substitution point for the unit tests.
It provides a flexible architecture that can be adapted as the overall design of the application evolves.

In Repository, we write our whole business logic of CRUD operations with the help of Entity Framework classes, that will not only result in meaningful test driven code but will also reduce our controller code of accessing data.

How can you call a javascript function/method on the change of Dropdown List in MVC?

Create a java-script method:

function selectedIndexChanged() {

}

</script>

Invoke the method:

<%:Html.DropDownListFor(x => x.SelectedProduct,

new SelectList(Model.Users, "Value", "Text"),

"Please Select a User", new { id = "ddlUsers",

onchange="selectedIndexChanged()" })%>

Explain Routing in MVC?

A route is a URL pattern that is mapped to a handler. The handler can be a physical

file, such as an .aspx file in a Web Forms application. Routing module is responsible for mapping incoming browser requests to particular MVC controller actions.

Routing within the ASP.NET MVC framework serves two main purposes:

· It matches incoming requests that would not otherwise match a file on the file system and maps the requests to a controller action.

· It constructs outgoing URLs that correspond to controller actions.

How route table is created in ASP.NET MVC?

When an MVC application first starts, the Application_Start() method in global.asax is called. This method, calls the RegisterRoutes() method. The RegisterRoutes() method creates the route table for MVC application.

What are Layouts in ASP.NET MVC Razor?

Layouts in Razor help maintain a consistent look and feel across multiple views within our application.As compared to Web Forms Web Forms, layouts serve the same purpose as master pages, but offer both a simpler syntax and greater flexibility.

We can use a layout to define a common template for your site (or just part of it). This template contains one or more placeholders that the other views in your application provide content for. In some ways, it’s like an abstract base class for your views.

e.g. declared at the top of view as,

Layout = "~/Views/Shared/SiteLayout.cshtml";

}

What is ViewStart?

For group of views that all use the same layout, this can get a bit redundant and harder to maintain.

The _ViewStart.cshtml page can be used to remove this redundancy. The code within this file

is executed before the code in any view placed in the same directory. This fi le is also recursively applied to any view within a subdirectory.

When we create a default ASP.NET MVC project, we find there is already a _ViewStart

.cshtml fi le in the Views directory. It specifi es a default layout:

Layout = "~/Views/Shared/_Layout.cshtml";

}

Because this code runs before any view, a view can override the Layout property and choose a different one. If a set of views shares common settings, the _ViewStart.cshtml file is a useful place to consolidate these common view settings. If any view needs to override any of the common settings, the view can set those values to another value.

Note: Some of the content has been taken from various books/articles.

What are HTML Helpers?

HTML helpers are methods we can invoke on the Html property of a view. We also have

access to URL helpers (via the Url property), and AJAX helpers (via the Ajax property). All

these helpers have the same goal: to make views easy to author. The URL helper is also available from within the controller.

Most of the helpers, particularly the HTML helpers, output HTML markup. For example, the

BeginForm helper is a helper we can use to build a robust form tag for our search

form, but without using lines and lines of code:

@using (Html.BeginForm("Search", "Home", FormMethod.Get)) {

}

What is Html.ValidationSummary?

The ValidationSummary helper displays an unordered list of all validation errors in the ModelState dictionary. The Boolean parameter you are using (with a value of true) is telling the helper to exclude property-level errors. In other words, you are telling the summary to display only the errors in ModelState associated with the model itself, and exclude any errors associated with a specific model property. We will be displaying property-level errors separately.Assume you have the following code somewhere in the controller action rendering the edit view:

ModelState.AddModelError("", "This is all wrong!");

ModelState.AddModelError("Title", "What a terrible name!");

The first error is a model-level error, because you didn’t provide a key (or provided an empty key) to associate the error with a specifi c property. The second error you associated with the Title property, so in your view it will not display in the validation summary area (unless you remove the parameter to the helper method, or change the value to false). In this scenario, the helper renders the following HTML:

<div class="validation-summary-errors">

<ul>

<li>This is all wrong!</li>

</ul>

</div>

Other overloads of the ValidationSummary helper enable you to provide header text and set specific HTML attributes.

NOTE By convention, the ValidationSummary helper renders the CSS class validation-summary-errors along with any specifi c CSS classes you provide.The default MVC project template includes some styling to display these items in red, which you can change in styles.css.

What are Validation Annotations?

Data annotations are attributes you can find in System.ComponentModel.DataAnnotations

namespace.These attributes provide server-side validation, and the framework also supports client-side validation when you use one of the attributes on a model property. You can use four attributes in the DataAnnotations namespace to cover common validation scenarios,

Required, String Length, Regular Expression, Range.

What is Html.Partial?

The Partial helper renders a partial view into a string. Typically, a partial view contains reusable markup you want to render from inside multiple different views. Partial has four overloads:

public void Partial(string partialViewName);

public void Partial(string partialViewName, object model);

public void Partial(string partialViewName, ViewDataDictionary viewData);

public void Partial(string partialViewName, object model,

ViewDataDictionary viewData);

What is Html.RenderPartial?

The RenderPartial helper is similar to Partial, but RenderPartial writes directly to the response output stream instead of returning a string. For this reason, you must place RenderPartial inside a code block instead of a code expression. To illustrate, the following two lines of code render the same output to the output stream:

@{Html.RenderPartial("AlbumDisplay "); }

@Html.Partial("AlbumDisplay ")

If they are same then which one to use?

In general, you should prefer Partial to RenderPartial because Partial is more convenient (you don’t have to wrap the call in a code block with curly braces). However, RenderPartial may result in better performance because it writes directly to the response stream, although it would require a lot of use (either high site traffic or repeated calls in a loop) before the difference would be noticeable.

How do you return a partial view from controller?

return PartialView(options); //options could be Model or View name

What are different ways of returning a View?

There are different ways for returning/rendering a view in MVC Razor.E.g. return View(), return RedirectToAction(), return Redirect() and return RedirectToRoute().

Conclusion:

I hope we covered a lot of questions to brush-up. Since MVC is very vast now,I know we have missed a lot stuff too.The content in the question and answer form is also taken from few renowned books like Professional asp.net MVC4 from wrox, and few of the content is taken from my MVC articles posted earlier. My upcoming articles will provide interview questions for EntityFramework too.

View my asp.net article of the day- Code First Approach using Entity Framework 4.1, Inversion of Control, Unity Framework, Repository & Unit of Work Pattern and MVC3 Razor View

Best of Luck and Happy Coding J.

Blogs...:)

Wednesday 30 April 2014

Really heart touching.........

Talent of Indians..:)

Thursday 10 April 2014

ASP.Net MVC Interview Questions and Answers...