MVC 4 – Interview question and answers

Below is the list of dotnet MVC 4 basic interview questions and answers. These MVC interview questions and answers are meant for freshers as well as for experienced developers. So, If you going for an interview on MVC, I suggest you to must give a look at following MVC interview questions. These MVC interview questions are based on basic introduction to MVC, why we need MVC, components of MVC, MVC namespaces, lifecycle of MVC application and a lot more. So lets have a look on following basic dotnet MVC interview questions and answers.

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?

“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.

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.

System.Web.Mvc

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

ASP.NET MVC

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.

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.

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.

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

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.

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

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

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.

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

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

In Application_Start event in Global.asax

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

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

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.

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.

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.

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

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.

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.

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.

{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.

{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.

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.

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

controller/{action}/{*parametervalues}

1. Use regular expressions

2. Use an object that implements IRouteConstraint interface

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.

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

1. Authorization filters

2. Action filters

3. Response filters

4. Exception filters

1. Authorization filters

2. Action filters

3. Result filters

4. Exception filters

1. RequireHttpsAttribute

2. AuthorizeAttribute

Authorization filter

1. Action Method

2. Controller

3. Application

Yes

Exception Filters

Yes

Result Filter

1. Razor

2. .aspx

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.

@

<%= %>

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

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

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

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

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

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

2. .vbhtml – If the programming lanugaue is VB

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

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.

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

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