fbpx

Top 100 MVC Interview Questions and Answers

Top 100 Deloitte Interview Questions and Answers
Contents show

1. What is MVC, and how does it work?

Answer: MVC is a design pattern that separates an application into three interconnected components: Model, View, and Controller. The Model represents data and business logic, the View handles user interface and presentation, and the Controller manages user input and communication between Model and View.


2. Explain the role of the Model in MVC.

Answer: The Model contains application data and business logic. It represents the application’s state and handles data manipulation, validation, and storage. It notifies the View and Controller of changes, ensuring synchronization.

// Example Model in C#
public class UserModel
{
    public int Id { get; set; }
    public string Name { get; set; }
}

3. Describe the responsibilities of the View in MVC.

Answer: The View is responsible for presenting data to users. It generates the user interface, displays data from the Model, and sends user input to the Controller for processing. It should not contain application logic.

<!-- Example View (HTML) -->
<h1>Welcome, @Model.Name!</h1>

4. What is the role of the Controller in MVC?

Answer: The Controller manages user interactions. It receives user input from the View, processes it, interacts with the Model to update data, and selects the appropriate View to display. It acts as an intermediary between the Model and View.

// Example Controller in C#
public class UserController : Controller
{
    public IActionResult Index()
    {
        var user = _userService.GetUser();
        return View(user);
    }
}

5. Explain the MVC routing mechanism.

Answer: MVC uses routing to map URLs to Controller actions. Routes are defined in the route configuration, and they determine which Controller and action should handle a specific URL request.

// Example MVC route in C#
routes.MapRoute(
    name: "Default",
    template: "{controller=Home}/{action=Index}/{id?}"
);

6. What are Action Filters in MVC, and why are they useful?

Answer: Action Filters are attributes applied to Controller actions to perform tasks like authentication, logging, and input validation. They allow you to execute code before or after an action method is invoked, enhancing the behavior of MVC actions.

// Example Action Filter in C#
[Authorize]
public IActionResult SecurePage()
{
    // Only accessible to authenticated users
    return View();
}

7. Describe TempData in MVC and its use cases.

Answer: TempData is a dictionary used to pass data between Controller actions during a single HTTP request. It’s useful for scenarios where you need to preserve data between redirects, such as after form submissions.

// Example TempData usage in C#
TempData["Message"] = "Success!";

8. What is the purpose of the ViewData dictionary in MVC?

Answer: ViewData is a dictionary that allows you to pass data from a Controller to a View. It’s a way to share data between the Controller and View without strong typing. However, it requires explicit casting in the View.

// Example ViewData usage in C#
ViewData["Message"] = "Hello, ViewData!";

9. Explain the concept of Model Binding in MVC.

Answer: Model Binding is the process of mapping HTTP request data to Model objects. MVC automatically binds form values, query strings, and route data to Model properties based on naming conventions, simplifying data handling.

// Example Model Binding in a Controller action
public IActionResult SaveUser(UserModel user)
{
    // Automatically binds form data to UserModel properties
    _userService.SaveUser(user);
    return RedirectToAction("Index");
}

10. What is the purpose of the JsonResult in MVC?

Answer: JsonResult is an ActionResult that returns JSON-formatted data. It’s commonly used for AJAX requests to provide data to client-side scripts.

// Example JsonResult in C#
public JsonResult GetUserData()
{
    var user = _userService.GetUser();
    return Json(user);
}

11. Explain the use of ViewBag in MVC and its limitations.

Answer: ViewBag is a dynamic property that allows you to pass data from a Controller to a View. Its limitations include lack of compile-time checking and potential runtime errors if property names are misspelled.

// Example ViewBag usage in C#
ViewBag.Message = "Hello, ViewBag!";

12. What is the purpose of TempData, ViewBag, and ViewData, and when would you use each?

Answer: TempData is used to pass data between Controller actions during a single request. ViewBag and ViewData are used to pass data from a Controller to a View. TempData is suitable for scenarios involving redirects, while ViewBag and ViewData are used within the same request.

// Example TempData usage
TempData["Message"] = "Temporary data";

// Example ViewBag usage
ViewBag.Message = "Hello, ViewBag!";

// Example ViewData usage
ViewData["Message"] = "Greetings, ViewData!";

13. How can you enable attribute-based routing in MVC?

Answer: Attribute-based routing is enabled by adding the [Route] attribute to a Controller or action method. It allows you to specify custom routes directly in the Controller or action.

// Example attribute-based routing in C#
[Route("api/[controller]")]
public class UsersController : Controller
{
    [HttpGet("{id}")]
    public IActionResult GetUser(int id)
    {
        // Action logic
    }
}

14. Explain the use of the [ValidateAntiForgeryToken] attribute in MVC.

Answer: The [ValidateAntiForgeryToken] attribute helps protect against cross-site request forgery (CSRF) attacks by ensuring that form submissions include a valid anti-forgery token. It’s applied to actions that modify data.

// Example usage of [ValidateAntiForgeryToken]
[HttpPost]
[ValidateAntiForgeryToken]
public IActionResult UpdateProfile(UserModel user)
{
    // Action logic
}

15. What is Dependency Injection (DI), and how is it implemented in ASP.NET MVC?

Answer: Dependency Injection is a design pattern that allows you to inject dependencies (e.g., services, repositories) into a class rather than creating them internally. In ASP.NET MVC, DI is implemented through the built-in DI container or third-party containers like Autofac or Unity.

// Example DI in ASP.NET Core MVC
public class UserController : Controller
{
    private readonly IUserService _userService;

    public UserController(IUserService userService)
    {
        _userService = userService;
    }

    // Actions using _userService
}

16. Describe the use of the TempData.Peek method in MVC.

Answer: TempData.Peek checks if a value with the specified key exists in TempData but doesn’t remove it. It’s useful when you want to access TempData data without consuming it, allowing you to use it in subsequent requests.

// Example TempData.Peek usage
if (TempData.Peek("Message") != null)
{
    // Access TempData without removing it
    var message = TempData["Message"];
}

17. Explain Partial Views in MVC and their benefits.

Answer: Partial Views are reusable components in MVC for rendering a portion of a page. They help modularize and simplify code by breaking complex views into smaller, manageable pieces, promoting code reusability.

// Example usage of Partial View in a View
@Html.Partial("_Header")

18. What are Action Results in MVC, and how do they differ from each other?

Answer: Action Results are return types for Controller actions. Common Action Results include ViewResult (renders a view), RedirectResult (redirects to a URL), and JsonResult (returns JSON data). They differ in how they handle the response to the client.

// Example action returning different Action Results
public IActionResult Index()
{
    return View(); // Renders a view
}

public IActionResult RedirectExample()
{
    return RedirectToAction("Index"); // Redirects to an action
}

public JsonResult GetUserData()
{
    return Json(user); // Returns JSON data
}

19. Explain the purpose of the @model directive in Razor views.

Answer: The @model directive in Razor views specifies the type of the Model expected by the view. It provides strong typing, enabling IntelliSense and compile-time checks for accessing Model properties in the view.

@model UserModel

<!-- Strongly-typed usage -->
<h1>Welcome, @Model.Name!</h1>

20. How can you handle errors and exceptions in an MVC application?

Answer: Errors and exceptions can be handled in MVC by using try-catch blocks in Controller actions, custom error pages, and global error handling via filters like HandleErrorAttribute. Additionally, you can log errors for debugging and monitoring.

// Example global error handling using HandleErrorAttribute
[HandleError]
public class HomeController : Controller
{
    // Action methods
}

21. What is the Razor view engine in MVC, and how does it differ from the Web Forms view engine?

Answer: Razor is the default view engine in MVC, providing a concise syntax for creating views. It differs from the Web Forms view engine by being more lightweight and having cleaner, HTML-like syntax, making it easier to read and maintain.

<!-- Razor syntax for displaying Model data -->
<h1>Welcome, @Model.Name!</h1>

22. Explain the purpose of the ActionResult class in MVC.

Answer: ActionResult is the base class for all action results in MVC. It represents the result of an action method and can be used to return various types of responses, such as views, JSON data, or redirects.

// Example returning different ActionResult types
public IActionResult Index()
{
    return View(); // ViewResult
}

public IActionResult RedirectExample()
{
    return RedirectToAction("Index"); // RedirectResult
}

public IActionResult GetUserData()
{
    return Json(user); // JsonResult
}

23. What is the difference between ViewBag and ViewData in MVC?

Answer: Both ViewBag and ViewData are used to pass data from a Controller to a View. The key difference is that ViewBag uses dynamic properties, while ViewData uses a dictionary. ViewBag has a simpler syntax but lacks compile-time checking.

// Example of ViewBag
ViewBag.Message = "Hello, ViewBag!";

// Example of ViewData
ViewData["Message"] = "Greetings, ViewData!";

24. Describe the use of the Area feature in MVC.

Answer: Areas in MVC allow you to organize the application into smaller, self-contained sections, each with its own Controllers, Views, and Models. This is useful for structuring large applications and isolating functionality.

// Example of defining an Area in MVC
[Area("Admin")]
public class AdminController : Controller
{
    // Actions specific to the Admin area
}

25. What are the benefits of using the ValidateAntiForgeryToken attribute in MVC?

Answer: The [ValidateAntiForgeryToken] attribute helps protect against CSRF attacks by ensuring that submitted forms include a valid anti-forgery token. This token is generated by the server and must match the one on the server to proceed with the action.

// Example usage of [ValidateAntiForgeryToken]
[HttpPost]
[ValidateAntiForgeryToken]
public IActionResult UpdateProfile(UserModel user)
{
    // Action logic
}

26. Explain the concept of Routing in MVC and how it maps URLs to actions.

Answer: Routing in MVC is the process of mapping URLs to Controller actions. Routes are defined in the route configuration, and they determine which Controller and action should handle a specific URL request. Routes are typically defined in the RouteConfig.cs file.

// Example MVC route configuration in C#
routes.MapRoute(
    name: "Default",
    template: "{controller=Home}/{action=Index}/{id?}"
);

27. How can you pass data from a View to a Controller in MVC?

Answer: Data from a View to a Controller can be passed through various methods:

  • Form submissions (HTTP POST)
  • Query strings in the URL (HTTP GET)
  • Route parameters
  • TempData, ViewData, or ViewBag
  • AJAX requests with JSON data
// Example of passing data through a form submission
[HttpPost]
public IActionResult SaveData(FormModel data)
{
    // Action logic
}

28. Explain the difference between RedirectToAction and Redirect in MVC.

Answer: RedirectToAction is used to redirect to a specific action method within the same or another Controller. Redirect is used to redirect to a specific URL, which can be a relative or absolute URL.

// Example of using RedirectToAction
return RedirectToAction("Index", "Home");

// Example of using Redirect
return Redirect("/Home/Index");

29. What is the purpose of the Authorize attribute in MVC, and how is it used?

Answer: The [Authorize] attribute restricts access to a Controller action to only authenticated users. It’s commonly used to protect certain parts of an application from unauthorized access.

// Example usage of [Authorize]
[Authorize]
public IActionResult SecurePage()
{
    // Only accessible to authenticated users
    return View();
}

30. Explain how to use RoutePrefix in MVC for grouping routes.

Answer: RoutePrefix is used to group routes under a common prefix in MVC. It simplifies route configuration and allows you to organize related actions within a Controller under a shared URL prefix.

// Example of using RoutePrefix
[RoutePrefix("api/users")]
public class UsersController : ApiController
{
    // Actions for managing users
}

31. What is the use of the ChildActionOnly attribute in MVC?

Answer: The [ChildActionOnly] attribute restricts an action method to be called only as a child action within a view, preventing direct access via URLs. It’s commonly used to render partial views within other views.

// Example usage of [ChildActionOnly]
[ChildActionOnly]
public PartialViewResult GetRecentPosts()
{
    // Logic to retrieve recent posts
    return PartialView(posts);
}

32. Explain the concept of Model Binding in MVC.

Answer: Model Binding in MVC automatically maps incoming HTTP request data (e.g., form fields, query strings) to action method parameters. It simplifies data retrieval from the request and validation.

// Example of Model Binding
public IActionResult SaveUser(UserModel user)
{
    // User model is automatically populated with request data
    // ModelState.IsValid can be used for validation
}

33. What is Dependency Injection, and how is it implemented in MVC?

Answer: Dependency Injection (DI) is a design pattern used in MVC to provide dependencies (e.g., services, repositories) to controllers and other components. It promotes loose coupling and testability.

// Example of constructor injection in MVC
public class HomeController : Controller
{
    private readonly IMyService _service;

    public HomeController(IMyService service)
    {
        _service = service;
    }
}

34. Explain the purpose of the ValidateAntiForgeryToken attribute in MVC and how to use it.

Answer: The [ValidateAntiForgeryToken] attribute helps protect against Cross-Site Request Forgery (CSRF) attacks by ensuring that the form submission includes a valid anti-forgery token. To use it, you should add the token to your form and apply the attribute to the action method.

// Example of using [ValidateAntiForgeryToken]
[HttpPost]
[ValidateAntiForgeryToken]
public IActionResult SubmitForm(FormModel data)
{
    // Action logic
}

35. What is the role of the @Html.ValidationSummary helper in MVC views?

Answer: @Html.ValidationSummary is used to display a summary of validation errors on a view. It renders a list of error messages generated during model validation.

<!-- Example of using @Html.ValidationSummary -->
@using (Html.BeginForm())
{
    @Html.ValidationSummary()
    <!-- Form fields and controls -->
}

36. How can you handle errors and exceptions in MVC?

Answer: Errors and exceptions in MVC can be handled in various ways:

  • Using try-catch blocks in action methods
  • Implementing custom error handling using filters
  • Configuring error pages in the Web.config
  • Using the Application_Error event in Global.asax.cs
// Example of custom error handling using filters
public class CustomErrorAttribute : FilterAttribute, IExceptionFilter
{
    public void OnException(ExceptionContext filterContext)
    {
        // Custom error handling logic
    }
}

37. Explain the concept of Output Caching in MVC and how to use it.

Answer: Output Caching in MVC stores the generated HTML output of a page or a portion of it in memory or on disk. It’s used to improve performance by serving cached content instead of re-rendering the same view repeatedly.

// Example of using Output Caching with a duration of 10 seconds
[OutputCache(Duration = 10)]
public ActionResult CachedPage()
{
    // Action logic
}

38. Describe the role of PartialViews in MVC and how to render them.

Answer: Partial Views in MVC are reusable view components that can be included in other views. They are useful for rendering common UI elements across multiple views.

<!-- Example of rendering a Partial View in a view -->
<div>
    @Html.Partial("_PartialViewName")
</div>

39. What is the purpose of ModelState in MVC, and how is it used for validation?

Answer: ModelState in MVC holds the state of model binding and validation. It’s used to check whether the model state is valid and display validation errors in views.

// Example of checking ModelState and displaying errors
if (!ModelState.IsValid)
{
    return View(model);
}

40. Explain the role of async and await keywords in MVC controllers.

Answer: The async and await keywords in MVC allow controllers to perform asynchronous operations without blocking the request thread. They are used for tasks like async database queries, improving application responsiveness.

// Example of using async/await in a controller action
public async Task<IActionResult> AsyncAction()
{
    var data = await _repository.GetDataAsync();
    return View(data);
}

41. What is the difference between TempData and ViewBag in MVC?

Answer: TempData and ViewBag both allow passing data between the controller and view, but they have differences:

  • TempData stores data for the duration of the current request and the next request. It’s typically used for redirect scenarios.
  • ViewBag is a dynamic property bag used to pass data from the controller to the view within the same request.
// Example of using TempData and ViewBag
TempData["Message"] = "This is TempData";
ViewBag.Message = "This is ViewBag";

42. How can you enable attribute routing in an MVC application?

Answer: Attribute routing in MVC allows defining routes directly on the controller actions using attributes like [Route]. To enable it, add MapMvcAttributeRoutes to the RouteConfig.cs file’s RegisterRoutes method.

// Example of enabling attribute routing in RouteConfig.cs
public static void RegisterRoutes(RouteCollection routes)
{
    routes.IgnoreRoute("{resource}.axd/{*pathInfo}");
    routes.MapMvcAttributeRoutes(); // Enable attribute routing
    // Other routes
}

43. Explain the purpose of IActionResult in MVC and provide examples of its use.

Answer: IActionResult in MVC represents the result of an action method and is used to return different types of HTTP responses. It allows flexibility in returning views, JSON, redirects, and more.

// Example of using IActionResult to return a View
public IActionResult Index()
{
    return View();
}

// Example of using IActionResult to return JSON data
public IActionResult GetJsonData()
{
    var data = new { Name = "John", Age = 30 };
    return Json(data);
}

44. What is the role of the Area feature in MVC, and how is it implemented?

Answer: In MVC, an Area is a way to organize related controllers, views, and models into separate sections of an application. Areas are commonly used in large applications to maintain modularity.

To implement an Area, you can:

  1. Create a folder with the area name in the project.
  2. Inside the area folder, create subfolders for controllers, views, and models.
  3. Define routes for the area in AreaRegistration.cs within the area folder.
// Example of defining routes for an Area
public class MyAreaRegistration : AreaRegistration 
{
    public override string AreaName => "MyArea";

    public override void RegisterArea(AreaRegistrationContext context) 
    {
        context.MapRoute(
            "MyArea_default",
            "MyArea/{controller}/{action}/{id}",
            new { action = "Index", id = UrlParameter.Optional }
        );
    }
}

45. How can you secure an MVC application from common security threats?

Answer: To secure an MVC application, consider these practices:

  • Use input validation and avoid direct object rendering in views.
  • Implement authentication and authorization using ASP.NET Identity or other authentication mechanisms.
  • Use HTTPS to protect data in transit.
  • Sanitize user inputs to prevent Cross-Site Scripting (XSS) attacks.
  • Avoid storing sensitive information in client-side code.
  • Apply security headers (e.g., Content Security Policy) to prevent security vulnerabilities.

46. Explain the purpose of ActionFilters in MVC and provide examples of their use.

Answer: Action Filters in MVC are attributes that can be applied to controller actions to add pre or post-processing logic. Commonly used action filters include Authorize, OutputCache, and custom filters.

// Example of using the [Authorize] action filter
[Authorize(Roles = "Admin")]
public IActionResult AdminAction()
{
    // Action logic for admin only
}

47. What is the role of the Web.config file in an MVC application?

Answer: The Web.config file in an MVC application contains configuration settings for the application, including connection strings, custom error pages, authentication settings, and more. It provides a centralized way to manage application-level configurations.

<!-- Example of custom error settings in Web.config -->
<customErrors mode="On" defaultRedirect="~/Error">
    <error statusCode="404" redirect="~/NotFound"/>
</customErrors>

48. Explain the difference between Html.RenderPartial and Html.Partial in MVC views.

Answer: Both Html.RenderPartial and Html.Partial are used to render partial views, but they differ in how they output the HTML:

  • Html.RenderPartial directly writes the HTML to the response stream and doesn’t return a string.
  • Html.Partial returns the HTML as a string, allowing further manipulation.
<!-- Example of using Html.RenderPartial -->
@{ Html.RenderPartial("_PartialViewName"); }

<!-- Example of using Html.Partial -->
<div>
    @Html.Partial("_PartialViewName")
</div>

49. How can you optimize the performance of an MVC application?

Answer: To optimize MVC application performance, consider:

  • Caching data and output using mechanisms like OutputCache.
  • Minimizing the number of HTTP requests by bundling and minifying static resources.
  • Implementing asynchronous actions for I/O-bound operations.
  • Using a Content Delivery Network (CDN) for serving static assets.
  • Optimizing database queries and indexing for efficient data retrieval.

50. Explain the purpose of the RoutePrefix attribute in MVC and provide an example.

Answer: The RoutePrefix attribute in MVC allows defining a common route prefix for a controller and its actions. It simplifies route configuration for multiple actions within the same controller.

[RoutePrefix("products")]
public class ProductController : Controller
{
    [Route("{id}")]
    public ActionResult Details(int id)
    {
        // Action logic
    }

    [Route("list")]
    public ActionResult List()
    {
        // Action logic
    }
}

51. What is the purpose of the ValidateAntiForgeryToken attribute in MVC, and how is it used?

Answer: The ValidateAntiForgeryToken attribute in MVC is used to prevent Cross-Site Request Forgery (CSRF) attacks by ensuring that form submissions come from a trusted source. To use it, decorate a controller action with the attribute and include a hidden anti-forgery token in the form.

[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult SubmitForm()
{
    // Action logic
}

52. Explain the difference between ActionResult and ViewResult in MVC.

Answer: ActionResult is a base class for all action results in MVC, while ViewResult is a specific type of ActionResult used to return a view. ViewResult represents the HTML and markup generated by a view template.

// Example of returning a ViewResult
public ViewResult Index()
{
    return View();
}

53. How can you handle errors and exceptions in an MVC application?

Answer: You can handle errors and exceptions in MVC using these methods:

  • Use try-catch blocks in action methods to catch exceptions.
  • Configure custom error pages in the Web.config file.
  • Implement a global error handler using the Application_Error event in Global.asax.
  • Use the HandleError attribute to specify error views for specific controllers or actions.

54. What is the role of the @model directive in Razor views, and how is it used?

Answer: The @model directive in Razor views specifies the type of the model that the view expects. It allows strong typing of the view, enabling IntelliSense and compile-time checking.

@model MyNamespace.MyModel

55. Explain the difference between ViewBag, ViewData, and TempData in MVC.

Answer: ViewBag, ViewData, and TempData are used to pass data from controllers to views.

  • ViewBag: Uses dynamic properties for loosely typed data.
  • ViewData: Uses a dictionary for loosely typed data.
  • TempData: Stores data for the current and next request.

56. How can you enable attribute-based routing in MVC 5?

Answer: In MVC 5, attribute-based routing can be enabled by adding routes.MapMvcAttributeRoutes(); to the RouteConfig.cs file in the App_Start folder. Ensure that the RouteConfig class is included in the Global.asax.cs file.

public static void RegisterRoutes(RouteCollection routes)
{
    routes.IgnoreRoute("{resource}.axd/{*pathInfo}");
    routes.MapMvcAttributeRoutes(); // Enable attribute routing
    // Other routes
}

57. Explain the purpose of the AuthorizeAttribute in MVC, and provide an example of its use.

Answer: The AuthorizeAttribute in MVC is used to restrict access to controller actions to authenticated users or users with specific roles. It is commonly used for implementing authentication and authorization in MVC applications.

[Authorize(Roles = "Admin")]
public ActionResult AdminAction()
{
    // Action logic for admin only
}

58. What is the role of the Global.asax file in an MVC application, and how can it be used?

Answer: The Global.asax file is used to handle application-level events and configurations. It can be used to register routes, handle errors, and perform application startup and shutdown tasks.

protected void Application_Start()
{
    AreaRegistration.RegisterAllAreas();
    RouteConfig.RegisterRoutes(RouteTable.Routes);
    // Other startup tasks
}

59. Explain the purpose of a ViewModel in MVC and how it differs from a model.

Answer: A ViewModel in MVC is a class specifically designed to represent data required by a view. It typically combines data from multiple models to simplify the view’s data needs. It differs from a model, which represents the data of a single entity.


60. How can you implement dependency injection in an MVC application, and why is it beneficial?

Answer: Dependency injection in MVC involves injecting dependencies (e.g., services, repositories) into controllers or other components. It’s beneficial for decoupling components, making testing easier, and promoting code reusability.

You can implement it using an IoC container like Unity, Ninject, or the built-in ASP.NET Core DI container.


61. What is the purpose of the Route attribute in MVC, and how is it used?

Answer: The Route attribute in MVC is used for defining custom routes for controller actions. It allows you to specify the URL pattern that maps to the action.

[Route("products/details/{id}")]
public ActionResult ProductDetails(int id)
{
    // Action logic for product details
}

62. Explain the concept of scaffolding in MVC and how it can be used to generate code.

Answer: Scaffolding in MVC is a code generation technique that creates controller actions, views, and associated code based on a model. It’s commonly used to quickly generate CRUD (Create, Read, Update, Delete) operations for a model.


63. What is the purpose of the ChildActionOnly attribute in MVC, and when is it used?

Answer: The ChildActionOnly attribute in MVC restricts an action method to be called only as a child action within a view. It prevents direct access to the action URL, ensuring that it’s only invoked within the context of a view.

[ChildActionOnly]
public ActionResult Widget()
{
    // Action logic for rendering a widget
}

64. How can you implement authentication and authorization in an MVC application?

Answer: Authentication in MVC can be implemented using various methods such as Forms Authentication, Windows Authentication, or OAuth. Authorization can be done using the [Authorize] attribute and specifying roles or policies.


65. What is the purpose of the ValidateAntiForgeryToken attribute in MVC, and how is it used?

Answer: The ValidateAntiForgeryToken attribute in MVC is used to prevent Cross-Site Request Forgery (CSRF) attacks by ensuring that form submissions come from a trusted source. To use it, decorate a controller action with the attribute and include a hidden anti-forgery token in the form.

[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult SubmitForm()
{
    // Action logic
}

66. Explain the difference between ActionResult and ViewResult in MVC.

Answer: ActionResult is a base class for all action results in MVC, while ViewResult is a specific type of ActionResult used to return a view. ViewResult represents the HTML and markup generated by a view template.

// Example of returning a ViewResult
public ViewResult Index()
{
    return View();
}

67. How can you handle errors and exceptions in an MVC application?

Answer: You can handle errors and exceptions in MVC using these methods:

  • Use try-catch blocks in action methods to catch exceptions.
  • Configure custom error pages in the Web.config file.
  • Implement a global error handler using the Application_Error event in Global.asax.
  • Use the HandleError attribute to specify error views for specific controllers or actions.

68. What is the role of the @model directive in Razor views, and how is it used?

Answer: The @model directive in Razor views specifies the type of the model that the view expects. It allows strong typing of the view, enabling IntelliSense and compile-time checking.

@model MyNamespace.MyModel

69. Explain the difference between ViewBag, ViewData, and TempData in MVC.

Answer: ViewBag, ViewData, and TempData are used to pass data from controllers to views.

  • ViewBag: Uses dynamic properties for loosely typed data.
  • ViewData: Uses a dictionary for loosely typed data.
  • TempData: Stores data for the current and next request.

70. How can you enable attribute-based routing in MVC 5?

Answer: In MVC 5, attribute-based routing can be enabled by adding routes.MapMvcAttributeRoutes(); to the RouteConfig.cs file in the App_Start folder. Ensure that the RouteConfig class is included in the Global.asax.cs file.

public static void RegisterRoutes(RouteCollection routes)
{
    routes.IgnoreRoute("{resource}.axd/{*pathInfo}");
    routes.MapMvcAttributeRoutes(); // Enable attribute routing
    // Other routes
}

71. What is the purpose of the PartialView in MVC, and how is it different from a regular view?

Answer: A PartialView in MVC is a reusable view component that can be embedded within other views. It allows you to break down complex views into smaller, manageable parts. The key difference is that a PartialView doesn’t have a layout, while regular views do.

@Html.Partial("_PartialViewName")

72. Explain the concept of model binding in MVC, and how does it work?

Answer: Model binding in MVC is the process of mapping HTTP request data (form values, query strings, route values, etc.) to action method parameters or model properties. It’s done automatically by the framework based on parameter names and data type matching.


73. What is a ViewModel in MVC, and why is it used?

Answer: A ViewModel in MVC is a custom class designed to represent the data and behavior needed by a view. It’s used to consolidate data from multiple models into a single object, simplifying the view’s interactions with the controller and models.

public class ProductViewModel
{
    public Product Product { get; set; }
    public List<Category> Categories { get; set; }
}

74. How can you enable attribute-based validation in MVC, and what are some common validation attributes?

Answer: Attribute-based validation in MVC can be enabled by adding validation attributes to model properties. Common validation attributes include [Required], [StringLength], [Range], [RegularExpression], and [Compare].

public class User
{
    [Required]
    public string Username { get; set; }

    [EmailAddress]
    public string Email { get; set; }
}

75. Explain the purpose of the Redirect and RedirectToAction methods in MVC, and how are they used?

Answer: Both Redirect and RedirectToAction methods are used to perform redirects in MVC.

  • Redirect is used to redirect to a specific URL.
  • RedirectToAction is used to redirect to a different action method within the same controller or a different controller.
public ActionResult RedirectExample()
{
    return Redirect("https://www.example.com");
}

public ActionResult RedirectToActionExample()
{
    return RedirectToAction("ActionName", "ControllerName");
}

76. What is a layout view in MVC, and how does it differ from a regular view?

Answer: A layout view in MVC is a template that defines the common structure of multiple views. It typically contains the HTML structure, headers, footers, and navigation menus. A regular view represents the content specific to a particular page.


77. How can you implement caching in MVC to improve application performance?

Answer: Caching in MVC can be implemented using the [OutputCache] attribute on controller actions or by configuring caching in the Web.config file. This helps store rendered views or data in memory or on disk, reducing the load on the server.

[OutputCache(Duration = 3600)] // Cache for 1 hour
public ActionResult CachedAction()
{
    // Action logic
}

78. Explain the concept of areas in MVC, and how can you organize code using areas?

Answer: Areas in MVC allow you to organize code into separate functional sections within an application. Each area can have its controllers, views, and models. This helps maintain a clean and organized codebase, especially in large applications.


79. What is the purpose of the HttpNotFound and HttpBadRequest methods in MVC, and when should they be used?

Answer: HttpNotFound is used to return a 404 Not Found response, indicating that a resource or page doesn’t exist. HttpBadRequest is used to return a 400 Bad Request response, indicating an invalid client request. They are typically used in error handling scenarios.

public ActionResult NotFoundExample()
{
    return HttpNotFound("Resource not found.");
}

public ActionResult BadRequestExample()
{
    return HttpBadRequest("Invalid request.");
}

80. How can you implement custom error handling and logging in an MVC application?

Answer: Custom error handling and logging can be implemented by creating custom error pages and using frameworks like log4net or Serilog to log errors. You can also use the HandleError attribute to specify error views.


81. Explain the role of the Web.config file in an MVC application, and what are some common configurations you can specify in it?

Answer: The Web.config file in an MVC application contains settings and configurations related to the application, including connection strings, custom error pages, authentication modes, and more. Common configurations include:

  • <connectionStrings>: Defines database connection strings.
  • <customErrors>: Configures custom error pages.
  • <authentication>: Specifies authentication modes.
  • <authorization>: Defines access control rules.
<configuration>
    <connectionStrings>
        <add name="DefaultConnection" connectionString="..." />
    </connectionStrings>
    <customErrors mode="On" defaultRedirect="Error">
        <error statusCode="404" redirect="NotFound" />
    </customErrors>
    <authentication mode="Forms">
        <forms loginUrl="Login" />
    </authentication>
    <authorization>
        <deny users="?"/>
    </authorization>
</configuration>

82. What is the purpose of the ValidateAntiForgeryToken attribute in MVC, and how does it enhance security?

Answer: The ValidateAntiForgeryToken attribute is used to prevent cross-site request forgery (CSRF) attacks in MVC applications. It ensures that a form submission originates from the same application by checking a hidden token in the form. This enhances security by preventing malicious form submissions from other domains.

[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult SubmitForm(FormModel model)
{
    // Form submission logic
}

83. Explain the role of the RouteConfig class in MVC, and how are routes defined in an MVC application?

Answer: The RouteConfig class is responsible for defining URL routing rules in an MVC application. It determines how URLs are mapped to controller actions. Routes are defined using the MapRoute method, specifying parameters like controller, action, and route values.

public static void RegisterRoutes(RouteCollection routes)
{
    routes.MapRoute(
        name: "Default",
        url: "{controller}/{action}/{id}",
        defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }
    );
}

84. What is the purpose of the ValidateAntiForgeryToken attribute in MVC, and how does it enhance security?

Answer: The ValidateAntiForgeryToken attribute is used to prevent cross-site request forgery (CSRF) attacks in MVC applications. It ensures that a form submission originates from the same application by checking a hidden token in the form. This enhances security by preventing malicious form submissions from other domains.

[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult SubmitForm(FormModel model)
{
    // Form submission logic
}

85. Explain the role of action filters in MVC, and provide examples of common built-in action filters.

Answer: Action filters in MVC are attributes that can be applied to controller actions to perform pre-processing or post-processing tasks. Common built-in action filters include:

  • AuthorizeAttribute: Enforces authorization rules.
  • OutputCacheAttribute: Caches the output of an action.
  • ValidateAntiForgeryTokenAttribute: Protects against CSRF attacks.
  • HandleErrorAttribute: Handles exceptions and redirects to error views.

86. What is the purpose of the ValidateAntiForgeryToken attribute in MVC, and how does it enhance security?

Answer: The ValidateAntiForgeryToken attribute is used to prevent cross-site request forgery (CSRF) attacks in MVC applications. It ensures that a form submission originates from the same application by checking a hidden token in the form. This enhances security by preventing malicious form submissions from other domains.

[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult SubmitForm(FormModel model)
{
    // Form submission logic
}

87. Explain the role of action filters in MVC, and provide examples of common built-in action filters.

Answer: Action filters in MVC are attributes that can be applied to controller actions to perform pre-processing or post-processing tasks. Common built-in action filters include:

  • AuthorizeAttribute: Enforces authorization rules.
  • OutputCacheAttribute: Caches the output of an action.
  • ValidateAntiForgeryTokenAttribute: Protects against CSRF attacks.
  • HandleErrorAttribute: Handles exceptions and redirects to error views.

88. What is the purpose of the TempData object in MVC, and how is it different from ViewBag and ViewData?

Answer: TempData in MVC is used to store data that persists only for the duration of the current HTTP request and the subsequent redirect. It’s useful for passing data between actions during redirects. Unlike ViewBag and ViewData, TempData is primarily used for redirection scenarios.

// Setting data in TempData
TempData["Message"] = "Data stored temporarily.";

// Retrieving data in another action after redirect
string message = TempData["Message"] as string;

89. How can you implement authentication and authorization in an MVC application?

Answer: Authentication in MVC can be implemented using authentication middleware like FormsAuthentication, Windows Authentication, or external identity providers like OAuth. Authorization can be enforced using the [Authorize] attribute, roles, or custom authorization filters.

[Authorize(Roles = "Admin")]
public ActionResult AdminPage()
{
    // Action logic for admin users
}

90. Explain the concept of dependency injection (DI) in MVC, and how can you implement it using built-in IoC containers?

Answer: Dependency injection in MVC involves providing dependencies (e.g., services, repositories) to controller classes rather than creating them directly. MVC supports DI through built-in IoC containers like Unity, StructureMap, and AutoFac. Dependencies are registered and injected into controllers via constructor or property injection.

public class MyController : Controller
{
    private readonly IMyService _myService;

    public MyController(IMyService myService)
    {
        _myService = myService;
    }

    // Controller actions using _myService
}

91. What is the purpose of the Web.config file in an MVC application, and what are some common configurations you can specify in it?

Answer: The Web.config file in an MVC application contains settings and configurations related to the application, including connection strings, custom error pages, authentication modes, and more. Common configurations include:

  • <connectionStrings>: Defines database connection strings.
  • <customErrors>: Configures custom error pages.
  • <authentication>: Specifies authentication modes.
  • <authorization>: Defines access control rules.
<configuration>
    <connectionStrings>
        <add name="DefaultConnection" connectionString="..." />
    </connectionStrings>
    <customErrors mode="On" defaultRedirect="Error">
        <error statusCode="404" redirect="NotFound" />
    </customErrors>
    <authentication mode="Forms">
        <forms loginUrl="Login" />
    </authentication>
    <authorization>
        <deny users="?"/>
    </authorization>
</configuration>

92. How does the ASP.NET MVC routing system work, and what is the significance of the RouteConfig class?

Answer: The ASP.NET MVC routing system maps URLs to controller actions. It uses route definitions in the RouteConfig class to determine which controller and action should handle a request. The RouteConfig class defines routes using the MapRoute method, which specifies URL patterns, default values, and constraints.

public static void RegisterRoutes(RouteCollection routes)
{
    routes.MapRoute(
        name: "Default",
        url: "{controller}/{action}/{id}",
        defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }
    );
}

93. Explain the role of action filters in MVC, and provide examples of common built-in action filters.

Answer: Action filters in MVC are attributes that can be applied to controller actions to perform pre-processing or post-processing tasks. Common built-in action filters include:

  • AuthorizeAttribute: Enforces authorization rules.
  • OutputCacheAttribute: Caches the output of an action.
  • ValidateAntiForgeryTokenAttribute: Protects against CSRF attacks.
  • HandleErrorAttribute: Handles exceptions and redirects to error views.

94. What is model binding in MVC, and how does it work?

Answer: Model binding in MVC is the process of mapping HTTP request data to action method parameters. MVC automatically binds form values, query string parameters, and route values to action method parameters based on their names. For example:

public ActionResult UpdateProfile(string username, int age)
{
    // username and age are automatically bound from the request
    // Action logic here
}

95. Explain the concept of dependency injection (DI) in MVC, and how can you implement it using built-in IoC containers?

Answer: Dependency injection in MVC involves providing dependencies (e.g., services, repositories) to controller classes rather than creating them directly. MVC supports DI through built-in IoC containers like Unity, StructureMap, and AutoFac. Dependencies are registered and injected into controllers via constructor or property injection.

public class MyController : Controller
{
    private readonly IMyService _myService;

    public MyController(IMyService myService)
    {
        _myService = myService;
    }

    // Controller actions using _myService
}

96. How can you implement authentication and authorization in an MVC application?

Answer: Authentication in MVC can be implemented using authentication middleware like FormsAuthentication, Windows Authentication, or external identity providers like OAuth. Authorization can be enforced using the [Authorize] attribute, roles, or custom authorization filters.

[Authorize(Roles = "Admin")]
public ActionResult AdminPage()
{
    // Action logic for admin users
}

97. What is the purpose of the TempData object in MVC, and how is it different from ViewBag and ViewData?

Answer: TempData in MVC is used to store data that persists only for the duration of the current HTTP request and the subsequent redirect. It’s useful for passing data between actions during redirects. Unlike ViewBag and ViewData, TempData is primarily used for redirection scenarios.

// Setting data in TempData
TempData["Message"] = "Data stored temporarily.";

// Retrieving data in another action after redirect
string message = TempData["Message"] as string;

98. What is the role of the Global.asax file in an MVC application, and what events can be handled in it?

Answer: The Global.asax file in an MVC application is used to handle application-level events such as application start, end, and error handling. Common events include Application_Start, Application_End, Application_Error, and more. It’s a central place for configuring application

-wide settings and handling events.

protected void Application_Start()
{
    // Application startup code
}

protected void Application_Error()
{
    // Global error handling
}

99. Explain the concept of areas in MVC, and why are they useful in large applications?

Answer: Areas in MVC allow you to organize a large application into smaller, manageable sections. Each area can contain its controllers, views, and models. They help maintain a clean project structure, separate concerns, and improve code organization in complex applications.


100. How can you optimize the performance of an MVC application? Provide some best practices.

Answer: To optimize MVC application performance:

  • Use caching for frequently accessed data.
  • Optimize database queries and indexing.
  • Minimize the use of synchronous operations.
  • Implement client-side caching for static assets.
  • Use bundling and minification for CSS and JavaScript.
  • Profile and optimize critical code paths.
  • Consider using a content delivery network (CDN) for assets.

These optimizations can significantly improve the speed and responsiveness of your MVC application.