ASP.NET MVC Interview Questions and Answers
In this article, I am going to discuss the most frequently asked MVC Interview Questions and answers. Let’s start the discussion with most frequently asked MVC Interview questions.
Explain MVC (Model-View-Controller) in general?
This is one of the most frequently asked ASP.NET MVC Interview Questions. So here we will discuss what is MVC design pattern is and what are the role and responsibilities of Model, View, and Controller in details.
MVC is an architectural software design pattern which is used for developing interactive applications where there would be user interaction involved and based on the user interaction some event handling occurs. So, this Model View Controller (MVC) design pattern is not only used for developing web-based applications but it can also be used for Desktop or mobile based applications where there are user interactions involved and based on the user interaction some event handling occurs.
This MVC (Model-View-Controller) design pattern was introduced in the 1970s which basically divides an application into 3 major components such as Model, View, and Controller. The main objective of the MVC design pattern is the separation of concerns. It means the domain model and business logic are separated from the user interface (i.e. view). Thus, maintenance and testing of the application become simpler and easier.
The Model is the component in MVC design pattern which manages that data i.e. state of the application in memory. It represents a set of classes which describe the applications business logic, validation logic, and data access logic. For example, an Employee object (Model) might retrieve the data from a database, operate on it, validate the data and then write the updated information back to an Employee table in the database. So the model is basically used to contain business (domain) data and business logic.
The view is the component in MVC design pattern which represents the user interface with which the end user can interact. Basically, the view is used to render the domain data (i.e. business data). It creates the user interface with data from the model with which the end user can interact. An example would be an edit view of a products table that displays text boxes, dropdown lists, and check boxes based on the current state of a product object.
The Controller is the component in MVC design pattern which contains the control flow logic. It is the one which will interact with both the models and views to control the flow of application execution. So, the controller component responds to user actions. Based on the user actions, the respective controller work with the model and view and sends responds back to the user.
What is ASP.NET MVC?
In many ASP.NET MVC interviews, they asked this question to check whether you know the difference between MVC and ASP.NET MVC. The first thing is first. So, remember both ASP.NET MVC and MVC are two different things altogether.
ASP.NET MVC is an open source web application development framework from Microsoft that is based on MVC (Model-View-Controller) architectural design pattern which provides a clean separation of code. This is the most customizable and extensible platform or framework provided by Microsoft.
So, the Point that you need to remember is, ASP.NET MVC is a Framework whereas MVC is a Design Pattern and the ASP.NET MVC Framework is based on MVC Design Pattern.
What are Model, View, and Controller from ASP.NET MVC Point of view?
We already discussed What are Model, View, and Controllers from MVC Design pattern Point of View. So, let discuss What are Model, View, and Controllers from ASP.NET MVC Point of view.
- In MVC, the models are basically C#.NET or VB.NET classes.
- The Models are basically used to manage the business data and business logic.
- This is the component which can be accessed by both controller and view.
- The model component can be used by a controller to pass the data to a view.
- It can also be used by a view, in order to display the data the in page (HTML output)
- In ASP.NET MVC application, the views are nothing but the cshtml or vbhtml pages without having a code behind file.
- All page specific HTML generation and formatting can be done inside view.
- A request to view can only be made from a controller’s action method.
- The view is only responsible for displaying the data.
- By default, views are stored in the Views folder of an ASP.NET MVC application.
- In ASP.NET MVC, the controller is basically a C# or VB.NET class which inherits from System.Web.Mvc.Controller.
- This is the component which has access to both the Models and Views in order to control the flow of the application execution.
- The Controller class contains action methods which are going to respond to the incoming URL.
- A controller can access and use the model classes to pass the data to a view.
- By default, controllers have stored in the Controllers folder an ASP.NET MVC application.
What are the Advantages of ASP.NET MVC?
This is one of the ASP.NET MVC questions asked in the interview to check whether you know why you are using MVC or not. So let us discuss what are the advantages of using ASP.NET MVC or you can say why we need to use ASP.NET MVC to develop a web application.
- The ASP.NET MVC Views are lightweight as compared to ASP.NET Web Forms because it does not use view state or any server-based forms or controls to render the data.
- As we are separating the view from the rest of the application which enables us to change of view (technology) in the future without affecting the rest of the application. For example, we might have views in Silverlight or HTML5.
- Each developer based on his expertise or experience can work on different parts of the application without stepping on each other toes. For example, one developer can work on the view while the second developer can work on the controller logic and the third developer can focus on the business logic in the model by interacting with the database.
- With the introduction of Attribute Routing, now it is very easy to create Restful or User-friendly URL’s which enable SEO to rank your page high.
- The ASP.NET MVC provides better support for test-driven development (TDD). This is because we can focus on one aspect at a time i.e. we can focus on the view without worrying about business logic as each component can be developed independently and also can be mocked easily.
- As the MVC design pattern divides the application into three major components such as Model, View, and Controller which make it easier to manage the application complexity.
- MVC framework components were designed to be pluggable and extensible and therefore can be replaced or customized in the future very easily
- AS the MVC framework is built on top of ASP.NET, so, we can use most of the ASP.NET features such as the authentication and authorization scenarios, membership and roles, caching, session and many more.
What is the difference between 3-layer architecture and MVC architecture?
The 3-layer architecture separates the application into 3 components which consist of Presentation Layer, Business Layer, and Data Access Layer. In 3-layer architecture, the user is going to interacts with the Presentation layer only. 3-layer is a linear architecture.
The MVC architecture separates the application into three major components such as Model, View, and Controller. In MVC architecture, the user is going to interacts with the controller with the help of view. MVC is a triangle architecture.
MVC does not replace 3-layer architecture. Typically MVC and 3-layer architecture are used together and the MVC Design Pattern acts as the Presentation layer of the application.
What are the differences between ASP.NET MVC and ASP.NET WebForms?
This is one of the Frequently asked ASP.NET MVC interview questions.
The ASP.NET Web Forms uses the Page controller pattern approach for rendering the layout whereas ASP.NET MVC uses the Front controller approach for rendering the layout. In the case of the Page controller Pattern approach, every aspx page having its own controller i.e. the code-behind file which is used to process the incoming request. Whereas, in ASP.NET MVC, a common controller can process the requests for all pages.
If you are visiting ASP.NET forums and communities, we will find the following questions frequently i.e.
- What is the difference between ASP.NET MVC and ASP.NET WebForms?
- Is ASP.NET MVC going to replace ASP.NET WebForms?
The first and the important thing that you need to remember is, the ASP.NET MVC Framework is not going to replace the ASP.NET WebForms Framework. Both technologies exist and both can be used to develop ASP.NET applications. Here we are going to discuss, what are the advantages and disadvantages of both these technologies one over another.
- In ASP.NET Web Forms there is no separation of concerns as every page (.aspx) has its own controller (i.e. code behind i.e. aspx.cs/.vb file). As a result, both are tightly coupled. Whereas the main objective of ASP.NET MVC is the clean separation of concerns as View and Controller are cleanly separate and also they are not tightly coupled.
- Because of the tightly coupled behavior in ASP.NET Web Forms (i.e. .aspx page and its code-behind file), unit testing is really a nightmare for a developer. Whereas in ASP.NET MVC unit testing is achieved very easily as they are not tightly coupled.
- ASP.NET Web Forms follows a Page Life cycle. Whereas in ASP.NET MVC there is no such Page Life cycle like Web Forms. Request cycle is simple in ASP.NET MVC model.
- ASP.NET MVC views are lightweight, as they do not use ViewState whereas ASP.NET Web Forms pages are not lightweight as they use ViewState.
- Complex applications can be easily managed in ASP.NET MVC because of separation of concerns. Different components of the application can be divided into Model, View, and Controller.
- ASP.NET web form has file based URLs means the file name exists in the URLs must have its physical existence whereas ASP.NET MVC has route based URLs means URLs are divided into controllers and actions and moreover it is based on controller not on physical file.
- ASP.NET web form has Master Pages for consistent looks and feels whereas ASP.NET MVC has Layouts for consistent looks and feels.
- ASP.NET web form has User Controls for code re-usability whereas ASP.NET MVC has Partial Views for code re-usability.
- ASP.NET Web Form is not Open Source whereas ASP.NET Web MVC is an Open Source.
- ASP.NET Web Form has server controls whereas ASP.NET MVC has HTML helpers.
Can you please explain the request flow in ASP.NET MVC framework?
If you are going for an ASP.NET MVC interview, then you definitely face this question i.e. Explain the Request Flow of ASP.NET MVC Application. So here you need to explain how a request is handled in ASP.NET MVC framework.
The Request flow for ASP.NET MVC framework is as follows:
In ASP.NET MVC application when the client makes a request for a resource from the browser then that request is handled by Routing engine and then the routing engine navigates that request to the appropriate Controller. Then the controller plays its role and executes the action method based on the user action and if needed then it works with the model object in order to serve the request. Once it works with the model, then it passes that model to a view and that view transforms that model and generates an appropriate response that is rendered to the client.
The point that you need to be noted that, the difference between WebForms and MVC is that in MVC we don’t have the Page concept whereas, in Legacy like ASP.NET Web Forms application, we do have pages like .aspx. So if your question is, Then how do the requests are been pointed in MVC? The answer is via Controllers. This special class is responsible for generating the response and sending the data back to the client.
For instance, the URL
Says that it is requesting for the Controller class name “Book” and the Action Method name called “Create”.
What are the important namespaces in ASP.NET MVC?
This question is not that important, but you should what are the important namespaces you used in ASP.NET MVC application. The following are some of the important namespaces:
- System.Web.Mvc – 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.
- System.Web.Mvc.Ajax – This namespace contains classes that support Ajax scripting in an ASP.NET MVC application. The namespace includes support for Ajax scripts and Ajax option settings as well.
- System.Web.Mvc.Html – This 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.
In the next article, I am going to discuss the Most Frequently asked ASP.NET MVC Routing Interview Questions and Answers.