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Top 100 ASP.NET MVC Interview Questions and Answers

Top 100 ASP.NET MVC Interview Questions and Answers

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1. What is ASP.NET MVC?

Answer: ASP.NET MVC is a web application framework developed by Microsoft, which implements the Model-View-Controller pattern. It allows developers to build dynamic, data-driven web applications.

// Example: Controller Action Method
public ActionResult Index()
{
    return View();
}

2. Explain the Model-View-Controller (MVC) pattern.

Answer: MVC is a design pattern that separates the application logic into three interconnected components: Model (data and business logic), View (UI presentation), and Controller (handles user interactions).

// Example: Model class
public class Product
{
    public int ProductId { get; set; }
    public string Name { get; set; }
}

3. What is a Razor View Engine in ASP.NET MVC?

Answer: Razor is a markup syntax used to create dynamic web pages with C# or VB.NET. It’s the default view engine in ASP.NET MVC and provides a clean and concise syntax for generating HTML.

<!-- Example: Razor syntax in a view -->
@model IEnumerable<Product>

@foreach (var product in Model)
{
    <div>@product.Name</div>
}

4. What is a ViewBag in ASP.NET MVC?

Answer: ViewBag is a dynamic property that allows the controller to pass data to the view. It is a way to communicate between the controller and the view.

// Example: Setting ViewBag in a controller action
public ActionResult Index()
{
    ViewBag.Message = "Welcome to our website!";
    return View();
}

5. Explain the difference between TempData and ViewData.

Answer:

  • ViewData: It’s used to pass data from the controller to the view, but it requires typecasting and is valid only for the current request.
  • TempData: It’s similar to ViewData, but it persists for an additional request, making it useful for scenarios like redirecting.
// Example: Setting TempData in a controller action
public ActionResult Index()
{
    TempData["Message"] = "Welcome!";
    return RedirectToAction("About");
}

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

Answer: Action Filters are attributes that can be applied to controller actions to perform logic before or after the action method executes. They help in extending controller behavior.

// Example: Custom Action Filter
public class LogActionFilter : ActionFilterAttribute
{
    public override void OnActionExecuting(ActionExecutingContext filterContext)
    {
        // Logic before action execution
    }
}

7. Explain the concept of Routing in ASP.NET MVC.

Answer: Routing is a way to define the URL pattern for an application. It maps a URL to a specific controller action method, allowing the application to respond to different URLs.

// Example: RouteConfig.cs
routes.MapRoute(
    name: "Default",
    url: "{controller}/{action}/{id}",
    defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }
);

8. What is the use of TempDataDictionary in ASP.NET MVC?

Answer: TempDataDictionary is used to pass data between controller actions when doing a redirect. It persists data for a single subsequent request.

// Example: Using TempData in a controller action
TempData["Message"] = "Data passed to the next action.";
return RedirectToAction("NextAction");

9. Explain Partial Views in ASP.NET MVC.

Answer: Partial Views are reusable views that can be rendered within other views. They allow for code reusability and help break complex views into smaller, manageable components.

<!-- Example: Rendering a Partial View -->
@Html.Partial("_PartialViewName")

10. What is the purpose of the Entity Framework in ASP.NET MVC?

Answer: The Entity Framework is an ORM (Object-Relational Mapping) framework that simplifies database interactions in an ASP.NET MVC application. It allows developers to work with databases using .NET objects.

// Example: Querying with Entity Framework
var products = dbContext.Products.Where(p => p.Category == "Electronics").ToList();

11. What is the use of the ActionResult class in ASP.NET MVC?

Answer: ActionResult is the base class for all action results in ASP.NET MVC. It represents the result of an action method and helps determine what should be rendered to the client.

// Example: Returning a ViewResult
public ActionResult Index()
{
    return View();
}

12. Explain the purpose of the @section directive in Razor Views.

Answer: The @section directive in Razor Views allows you to define content that can be overridden in child views. It’s useful for creating consistent layouts with dynamic content.

<!-- Example: Defining a section in a layout view -->
@section Scripts {
    <script src="~/Scripts/myscript.js"></script>
}

13. What is scaffolding in ASP.NET MVC?

Answer: Scaffolding is a code generation framework in ASP.NET MVC that creates basic CRUD (Create, Read, Update, Delete) operations for a model. It helps bootstrap the development process.

# Example: Generating a controller with scaffolding
Scaffold-Controller Product -DbContext MyDbContext

14. How do you handle errors in ASP.NET MVC?

Answer: Errors in ASP.NET MVC can be handled using custom error pages, exception filters, and the HandleError attribute. The HandleError attribute allows you to specify error views.

// Example: Applying HandleError attribute in a controller
[HandleError(View = "CustomError")]
public class HomeController : Controller
{
    // ...
}

15. What is the purpose of the Authorize attribute in ASP.NET MVC?

Answer: The Authorize attribute is used to restrict access to a specific action method or controller to only authenticated users. It helps in implementing authentication and authorization.

// Example: Applying Authorize attribute in a controller
[Authorize]
public class AdminController : Controller
{
    // ...
}

16. Explain the role of the Web.config file in an ASP.NET MVC application.

Answer: The Web.config file is a configuration file that contains settings for an ASP.NET MVC application. It includes configurations for various aspects like connection strings, app settings, and more.

<!-- Example: Connection string configuration in Web.config -->
<connectionStrings>
    <add name="DefaultConnection" connectionString="..." providerName="System.Data.SqlClient" />
</connectionStrings>

17. What is the purpose of the @Html.Action method in Razor Views?

Answer: @Html.Action is a method in Razor Views that invokes a controller action and renders the result as HTML. It’s used to include the output of another action within a view.

<!-- Example: Invoking an action in a view -->
@Html.Action("ActionName", "ControllerName")

18. How do you handle form submissions in ASP.NET MVC?

Answer: Form submissions in ASP.NET MVC are handled by creating a post action method in a controller. This method receives the form data and processes it.

// Example: Handling form submission in a controller
[HttpPost]
public ActionResult SubmitForm(FormViewModel model)
{
    // Process form data
    return RedirectToAction("Success");
}

19. Explain the purpose of the TempData attribute in ASP.NET MVC.

Answer: TempData is a dictionary that helps in passing data between actions when doing a redirect. It persists data for a single subsequent request.

// Example: Using TempData in a controller action
TempData["Message"] = "Data passed to the next action.";
return RedirectToAction("NextAction");

20. What is the purpose of the ValidateAntiForgeryToken attribute in ASP.NET MVC?

Answer: ValidateAntiForgeryToken is a security feature in ASP.NET MVC that prevents cross-site request forgery (CSRF) attacks. It ensures that a form submission originates from the legitimate site.

// Example: Applying ValidateAntiForgeryToken attribute
[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult SubmitForm(FormViewModel model)
{
    // Process form data
    return RedirectToAction("Success");
}

21. How does routing work in ASP.NET MVC?

Answer: Routing in ASP.NET MVC maps URLs to specific controller actions. It’s defined in the RouteConfig.cs file and determines which controller and action should handle a particular request.

// Example: Route configuration in RouteConfig.cs
routes.MapRoute(
    name: "Default",
    url: "{controller}/{action}/{id}",
    defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }
);

22. Explain the purpose of the ModelState object in ASP.NET MVC.

Answer: ModelState is used to represent the state of a model (typically after a POST request). It contains information about any errors that occurred during model binding.

// Example: Checking if the model state is valid in a controller action
if (ModelState.IsValid)
{
    // Process the data
    return RedirectToAction("Success");
}

23. What is the role of the IActionResult interface in ASP.NET MVC?

Answer: IActionResult is an interface representing the result of an action method. It provides flexibility in returning different types of results, such as views, JSON, redirects, etc.

// Example: Returning a JSON result
public IActionResult GetJsonData()
{
    var data = new { Name = "John Doe", Age = 30 };
    return Json(data);
}

24. How do you implement dependency injection in ASP.NET MVC?

Answer: Dependency injection in ASP.NET MVC is achieved through the built-in IServiceProvider. It’s typically configured in the Startup.cs file.

// Example: Registering a service in Startup.cs
services.AddTransient<IMyService, MyService>();

25. Explain the purpose of the ViewBag object in ASP.NET MVC.

Answer: ViewBag is a dynamic property that allows passing data from a controller to a view. It’s a convenient way to share data between the controller and view.

// Example: Setting ViewBag in a controller action
ViewBag.Title = "Welcome to the website";

26. What is the difference between ViewResult and PartialViewResult in ASP.NET MVC?

Answer: ViewResult is used to return a complete HTML page, while PartialViewResult returns a portion of HTML content. Partial views are often used to render parts of a page that need to be dynamically updated.

// Example: Returning a partial view
public PartialViewResult GetPartialView()
{
    return PartialView("_PartialViewName");
}

27. How do you handle errors in ASP.NET MVC?

Answer: Errors can be handled using custom error pages, exception filters, and the HandleError attribute. The HandleError attribute allows specifying error views.

// Example: Applying HandleError attribute in a controller
[HandleError(View = "CustomError")]
public class HomeController : Controller
{
    // ...
}

28. Explain the purpose of the Html.BeginForm method in Razor Views.

Answer: Html.BeginForm is a method in Razor Views that generates the opening <form> tag. It’s used to create HTML forms that can be submitted to a controller action.

<!-- Example: Creating a form in a view -->
@using (Html.BeginForm("SubmitForm", "Home", FormMethod.Post))
{
    // Form fields go here
    <button type="submit">Submit</button>
}

29. What is the purpose of the RouteValues parameter in RedirectToAction?

Answer: The RouteValues parameter in RedirectToAction allows you to pass additional data to the action being redirected to. It’s useful for providing context or information.

// Example: Redirecting with route values
return RedirectToAction("Details", "Product", new { id = 123 });

30. How do you enable attribute routing in ASP.NET MVC?

Answer: Attribute routing is enabled by adding the [Route] attribute to a controller or action method. It allows you to define routes directly on the controller or action.

// Example: Applying Route attribute to an action
[Route("products/details/{id}")]
public IActionResult Details(int id)
{
    // ...
}

31. What is the purpose of TempData in ASP.NET MVC?

Answer: TempData is used to pass data from the current request to the next request. It’s useful for scenarios where you need to persist data across redirects.

// Example: Setting TempData in a controller action
TempData["Message"] = "Operation successful!";

32. Explain the role of the ValidateAntiForgeryToken attribute.

Answer: The [ValidateAntiForgeryToken] attribute is used to prevent Cross-Site Request Forgery (CSRF) attacks. It ensures that a request comes from a trusted source by validating a token.

// Example: Applying ValidateAntiForgeryToken attribute
[HttpPost]
[ValidateAntiForgeryToken]
public IActionResult SubmitForm(FormViewModel model)
{
    // ...
}

33. What is the difference between ViewBag, ViewData, and TempData?

Answer:

  • ViewBag is a dynamic property for passing data from controller to view.
  • ViewData is a dictionary-like object that achieves the same purpose as ViewBag.
  • TempData is used to pass data from the current request to the next.
// Example: Setting ViewData in a controller action
ViewData["Message"] = "Welcome!";

34. How do you implement authentication and authorization in ASP.NET MVC?

Answer: Authentication can be implemented using ASP.NET Core Identity or other authentication providers. Authorization is done using [Authorize] attribute or custom authorization filters.

// Example: Applying Authorize attribute to a controller
[Authorize(Roles = "Admin")]
public class AdminController : Controller
{
    // ...
}

35. Explain the purpose of async and await in ASP.NET MVC.

Answer: async and await are used for asynchronous programming in ASP.NET MVC. They allow non-blocking execution of code, which improves responsiveness in web applications.

// Example: Using async/await in a controller action
public async Task<IActionResult> LoadDataAsync()
{
    var data = await _dataService.GetDataAsync();
    return View(data);
}

36. What is the role of the BundleConfig class in ASP.NET MVC?

Answer: BundleConfig is used to define bundles of CSS and JavaScript files. Bundling reduces the number of HTTP requests, improving page load times.

// Example: Registering bundles in BundleConfig.cs
bundles.Add(new ScriptBundle("~/bundles/jquery").Include(
            "~/Scripts/jquery-{version}.js"));

37. How do you implement error handling in ASP.NET MVC?

Answer: Error handling can be done using try-catch blocks, custom error pages, exception filters, and the HandleError attribute.

// Example: Applying HandleError attribute in a controller
[HandleError(View = "CustomError")]
public class HomeController : Controller
{
    // ...
}

38. Explain the purpose of Area in ASP.NET MVC.

Answer: Areas allow partitioning a large ASP.NET MVC application into smaller functional groups. They help in organizing controllers, views, and models.

// Example: Creating an area in ASP.NET MVC
public class AdminAreaRegistration : AreaRegistration 
{
    // ...
}

39. How do you implement routing in ASP.NET MVC?

Answer: Routing in ASP.NET MVC is configured in the RouteConfig.cs file. It defines the pattern for URLs and maps them to controller actions.

// Example: Defining a custom route in RouteConfig.cs
routes.MapRoute(
    name: "CustomRoute",
    url: "custom/{action}/{id}",
    defaults: new { controller = "Custom", action = "Index", id = UrlParameter.Optional }
);

40. Explain the purpose of the ValidateAntiForgeryToken attribute.

Answer: The [ValidateAntiForgeryToken] attribute is used to prevent Cross-Site Request Forgery (CSRF) attacks. It ensures that a request comes from a trusted source by validating a token.

// Example: Applying ValidateAntiForgeryToken attribute
[HttpPost]
[ValidateAntiForgeryToken]
public IActionResult SubmitForm(FormViewModel model)
{
    // ...
}

41. What is the difference between ViewBag, ViewData, and TempData?

Answer:

  • ViewBag is a dynamic property for passing data from controller to view.
  • ViewData is a dictionary-like object that achieves the same purpose as ViewBag.
  • TempData is used to pass data from the current request to the next.
// Example: Setting ViewData in a controller action
ViewData["Message"] = "Welcome!";

42. How do you implement authentication and authorization in ASP.NET MVC?

Answer: Authentication can be implemented using ASP.NET Core Identity or other authentication providers. Authorization is done using [Authorize] attribute or custom authorization filters.

// Example: Applying Authorize attribute to a controller
[Authorize(Roles = "Admin")]
public class AdminController : Controller
{
    // ...
}

43. Explain the purpose of async and await in ASP.NET MVC.

Answer: async and await are used for asynchronous programming in ASP.NET MVC. They allow non-blocking execution of code, which improves responsiveness in web applications.

// Example: Using async/await in a controller action
public async Task<IActionResult> LoadDataAsync()
{
    var data = await _dataService.GetDataAsync();
    return View(data);
}

44. What is the role of the BundleConfig class in ASP.NET MVC?

Answer: BundleConfig is used to define bundles of CSS and JavaScript files. Bundling reduces the number of HTTP requests, improving page load times.

// Example: Registering bundles in BundleConfig.cs
bundles.Add(new ScriptBundle("~/bundles/jquery").Include(
            "~/Scripts/jquery-{version}.js"));

45. How do you implement error handling in ASP.NET MVC?

Answer: Error handling can be done using try-catch blocks, custom error pages, exception filters, and the HandleError attribute.

// Example: Applying HandleError attribute in a controller
[HandleError(View = "CustomError")]
public class HomeController : Controller
{
    // ...
}

46. Explain the purpose of Area in ASP.NET MVC.

Answer: Areas allow partitioning a large ASP.NET MVC application into smaller functional groups. They help in organizing controllers, views, and models.

// Example: Creating an area in ASP.NET MVC
public class AdminAreaRegistration : AreaRegistration 
{
    // ...
}

47. How do you handle exceptions globally in ASP.NET MVC?

Answer: You can use the Application_Error event in the Global.asax file to handle exceptions globally.

protected void Application_Error(object sender, EventArgs e)
{
    Exception ex = Server.GetLastError();
    // Handle the exception
}

48. What is a partial view in ASP.NET MVC?

Answer: A partial view is a reusable view that can be rendered within another view. It allows for better code organization and reusability.

// Example: Rendering a partial view in a view
@Html.Partial("_PartialViewName")

49. How do you implement AJAX in ASP.NET MVC?

Answer: AJAX in ASP.NET MVC can be implemented using jQuery’s $.ajax() function or by using Ajax.BeginForm() in combination with the Ajax helpers.

// Example: Making an AJAX request with jQuery
$.ajax({
    url: "/Controller/Action",
    type: "GET",
    success: function(result) {
        // Handle the result
    }
});

50. Explain the purpose of the OutputCache attribute.

Answer: The [OutputCache] attribute is used to cache the output of a controller action. It improves performance by serving cached content for subsequent requests.

// Example: Applying OutputCache attribute to a controller action
[OutputCache(Duration = 3600, VaryByParam = "none")]
public ActionResult CachedAction()
{
    // ...
}

51. How do you handle form submissions in ASP.NET MVC?

Answer: Form submissions are handled by controller actions. The HttpPost attribute is used to specify that the action responds to POST requests.

// Example: Handling a form submission in a controller action
[HttpPost]
public ActionResult SubmitForm(FormViewModel model)
{
    // Process form data
    return RedirectToAction("Success");
}

52. Explain the purpose of the ChildActionOnly attribute.

Answer: The [ChildActionOnly] attribute restricts an action method to be called only as a child action, and not directly as a result of a user request.

// Example: Applying ChildActionOnly attribute to a controller action
[ChildActionOnly]
public ActionResult ChildAction()
{
    return PartialView("_ChildView");
}

53. How do you implement dependency injection in ASP.NET MVC?

Answer: Dependency injection can be implemented using an Inversion of Control (IoC) container like Autofac, Unity, or built-in .NET Core services.

// Example: Registering dependencies in Autofac
builder.RegisterType<DataService>().As<IDataService>();

54. Explain the purpose of the AsyncController in ASP.NET MVC.

Answer: AsyncController allows handling asynchronous requests. It helps in releasing server resources to handle other requests while waiting for long-running tasks.

// Example: Creating an asynchronous action in an AsyncController
public async Task<ActionResult> LongRunningAction()
{
    var result = await _service.PerformLongRunningTaskAsync();
    return View(result);
}

55. What is the role of TempData in ASP.NET MVC?

Answer: TempData is used to pass data from the current request to the next request, specifically during redirects. It is useful for scenarios where you need to show a message to the user after a redirect.

// Example: Setting TempData in a controller action
TempData["Message"] = "Operation successful!";

56. How do you enable attribute routing in ASP.NET MVC?

Answer: Attribute routing can be enabled by adding routes.MapMvcAttributeRoutes() in the RouteConfig.cs file.

// Example: Enabling attribute routing in RouteConfig.cs
public class RouteConfig
{
    public static void RegisterRoutes(RouteCollection routes)
    {
        routes.IgnoreRoute("{resource}.axd/{*pathInfo}");

        routes.MapMvcAttributeRoutes(); // Enable attribute routing

        // ...
    }
}

57. Explain the purpose of the ValidateAntiForgeryToken attribute.

Answer: The [ValidateAntiForgeryToken] attribute is used to prevent cross-site request forgery (CSRF) attacks. It ensures that the form submission is legitimate and originates from the correct site.

// Example: Applying ValidateAntiForgeryToken attribute to a controller action
[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult SubmitForm(FormViewModel model)
{
    // Process form data
    return RedirectToAction("Success");
}

58. What is the purpose of the Authorize attribute in ASP.NET MVC?

Answer: The [Authorize] attribute restricts access to a controller or action to only authenticated users. It is used for implementing authentication and authorization in MVC applications.

// Example: Applying Authorize attribute to a controller or action
[Authorize]
public class AdminController : Controller
{
    // ...
}

59. How do you implement custom error handling in ASP.NET MVC?

Answer: Custom error handling can be implemented by overriding the OnException method in a base controller or by using the HandleError attribute.

// Example: Custom error handling in a base controller
protected override void OnException(ExceptionContext filterContext)
{
    // Handle the exception
    filterContext.ExceptionHandled = true;
    // ...
}

60. Explain the purpose of the RouteLink helper in ASP.NET MVC.

Answer: The @Html.RouteLink helper generates a hyperlink to a specific route. It is used to create links based on route names defined in the RouteConfig.

// Example: Creating a link using RouteLink helper
@Html.RouteLink("Link Text", "RouteName")

61. What is the difference between ViewResult and ActionResult in ASP.NET MVC?

Answer:

  • ViewResult is used to return a view as a result of an action method.
  • ActionResult is a base class for action results, which includes ViewResult, RedirectResult, etc.
// Example: Returning a ViewResult from an action method
public ViewResult Index()
{
    return View();
}

// Example: Returning an ActionResult with a specific status code
public ActionResult NotFound()
{
    return HttpNotFound();
}

62. How can you handle exceptions in ASP.NET MVC?

Answer: Exceptions can be handled using try-catch blocks in action methods or by overriding the OnException method in a base controller. Additionally, the HandleError attribute can be applied to controllers or actions.

// Example: Handling exceptions in an action method
public ActionResult ProcessForm(FormModel model)
{
    try
    {
        // Code that may throw an exception
    }
    catch (Exception ex)
    {
        // Handle the exception
    }
}

63. What is the purpose of the PartialViewResult in ASP.NET MVC?

Answer: PartialViewResult is used to return a partial view from an action method. A partial view is a portion of a view that can be rendered within another view.

// Example: Returning a PartialViewResult from an action method
public PartialViewResult LoadComments(int postId)
{
    var comments = GetComments(postId);
    return PartialView("_CommentsPartial", comments);
}

64. Explain the role of a view model in ASP.NET MVC.

Answer: A view model is a class that is specifically designed for a view. It contains the data and behavior needed by the view to render the user interface. View models help in separating concerns and managing complex data for the view.

// Example: Creating a view model for a user registration form
public class RegisterViewModel
{
    public string Username { get; set; }
    public string Password { get; set; }
    // Additional properties and validation logic
}

65. How can you implement caching in ASP.NET MVC?

Answer: Caching can be implemented using the OutputCache attribute on a controller action or by using the OutputCache directive in a view.

// Example: Applying OutputCache attribute to a controller action
[OutputCache(Duration = 3600)]
public ActionResult CachedAction()
{
    return View();
}

66. What is routing in ASP.NET MVC?

Answer: Routing is the process of mapping a URL to a specific action method in a controller. It defines how the application responds to client requests.

// Example: Configuring a route in RouteConfig.cs
public class RouteConfig
{
    public static void RegisterRoutes(RouteCollection routes)
    {
        routes.MapRoute(
            name: "Default",
            url: "{controller}/{action}/{id}",
            defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }
        );
    }
}

67. How can you pass data from a controller to a view in ASP.NET MVC?

Answer: Data can be passed to a view using the ViewBag, ViewData, or by using strongly-typed view models.

// Example: Using ViewBag to pass data to a view
public ActionResult Index()
{
    ViewBag.Message = "Welcome to the Index view!";
    return View();
}

68. What is the purpose of the TempData object in ASP.NET MVC?

Answer: TempData is used to pass data from the current request to the next request. It is useful when redirecting to another action, as it persists for only one additional request.

// Example: Using TempData to pass data to the next request
public ActionResult SaveData(FormModel model)
{
    TempData["Message"] = "Data saved successfully!";
    return RedirectToAction("Index");
}

69. Explain the concept of Areas in ASP.NET MVC.

Answer: Areas allow you to organize a large project into smaller functional sections. Each area can have its own controllers, views, models, and other resources.

// Example: Creating an Area named "Admin"
public class AdminAreaRegistration : AreaRegistration 
{
    public override string AreaName 
    {
        get 
        {
            return "Admin";
        }
    }

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

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

Answer: Attribute-based routing can be enabled by adding the MapMvcAttributeRoutes method in the RegisterRoutes method of RouteConfig.cs.

// Example: Enabling attribute-based routing in RouteConfig.cs
public class RouteConfig
{
    public static void RegisterRoutes(RouteCollection routes)
    {
        routes.IgnoreRoute("{resource}.axd/{*pathInfo}");

        routes.MapMvcAttributeRoutes(); // Enable attribute-based routing

        // ... other routes
    }

71. What is the use of the [HttpPost] attribute in ASP.NET MVC?

Answer: The [HttpPost] attribute is used to restrict an action method to respond only to HTTP POST requests. It is commonly used for actions that involve data submission or modification.

[HttpPost]
public ActionResult Create(FormModel model)
{
    // Process the form data
    return RedirectToAction("Index");
}

72. Explain the purpose of the ActionResult in ASP.NET MVC.

Answer: ActionResult is the base class for all action result types in MVC. It represents the result of an action method and can be used to return views, partial views, redirects, JSON, and more.

public ActionResult Index()
{
    return View(); // Returns a view as the result
}

73. What is the role of the Web.config file in an ASP.NET MVC application?

Answer: The Web.config file is the configuration file for an ASP.NET application. It contains settings that affect how the application behaves, such as connection strings, application-level settings, and custom configurations.

<!-- Example: Connection string configuration in Web.config -->
<connectionStrings>
    <add name="DefaultConnection" connectionString="..." providerName="System.Data.SqlClient" />
</connectionStrings>

74. How can you handle errors in an ASP.NET MVC application?

Answer: Errors can be handled in ASP.NET MVC using custom error pages, global error handling, or by using the HandleError attribute. Additionally, logging frameworks like Serilog or NLog can be used to log errors.

// Example: Applying HandleError attribute in a controller
[HandleError]
public class HomeController : Controller
{
    // Controller actions
}

75. What is the purpose of the Layout view in ASP.NET MVC?

Answer: The Layout view defines the common structure, such as headers, footers, and navigation, for multiple views. It allows for a consistent look and feel across the application.

<!-- Example: Defining a Layout view in _Layout.cshtml -->
<!DOCTYPE html>
<html>
<head>
    <!-- Common head content -->
</head>
<body>
    @RenderBody() <!-- Placeholder for view content -->
    <!-- Common footer content -->
</body>
</html>

76. Explain the concept of routing in ASP.NET MVC.

Answer: Routing in ASP.NET MVC is the process of mapping a URL to a specific controller action. It determines which controller and action should be invoked based on the requested URL.

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

77. What is the purpose of the ValidateAntiForgeryToken attribute in ASP.NET MVC?

Answer: The [ValidateAntiForgeryToken] attribute is used to prevent Cross-Site Request Forgery (CSRF) attacks. It ensures that a form submission originates from the correct site and protects against unauthorized requests.

[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult SubmitForm(FormModel model)
{
    // Process the form data
    return RedirectToAction("Success");
}

78. How can you implement authentication and authorization in ASP.NET MVC?

Answer: Authentication verifies the identity of a user, while authorization determines what actions a user is allowed to perform. This can be achieved using ASP.NET Identity, custom authentication methods, and role-based or claims-based authorization.

// Example: Authorize attribute in a controller action
[Authorize(Roles = "Admin")]
public ActionResult AdminDashboard()
{
    // Admin-only functionality
    return View();
}

79. Explain the purpose of the TempData dictionary in ASP.NET MVC.

Answer: TempData is used to pass data from the current request to the next request. It is typically used to show a message after a redirect, such as after a form submission.

// Example: Setting TempData in a controller action
public ActionResult SubmitForm(FormModel model)
{
    TempData["SuccessMessage"] = "Form submitted successfully!";
    return RedirectToAction("Success");
}

80. How can you optimize the performance of an ASP.NET MVC application?

Answer: Performance optimization in ASP.NET MVC can be achieved by techniques like caching, bundling and minification of static resources, optimizing database queries, and using asynchronous programming.

// Example: Output caching in a controller action
[OutputCache(Duration = 60)] // Cache for 60 seconds
public ActionResult Index()
{
    // Controller logic
    return View();
}

81. How does model binding work in ASP.NET MVC?

Answer: Model binding is the process of mapping HTTP request data to the parameters of a controller action. It automatically populates the action method parameters with values from the request.

// Example: Controller action with model binding
public ActionResult SaveProduct(ProductViewModel product)
{
    // 'product' is automatically populated from the request data
    // Process and save the product
    return RedirectToAction("Index");
}

82. What is the role of the ViewBag and ViewData in ASP.NET MVC?

Answer: Both ViewBag and ViewData are used to pass data from the controller to the view. ViewBag is a dynamic property that uses dynamic typing, while ViewData is a dictionary-like object.

// Example: Setting data in ViewBag
public ActionResult Index()
{
    ViewBag.Message = "Welcome to the Index page!";
    return View();
}

83. Explain the purpose of the @section directive in Razor views.

Answer: The @section directive in Razor views allows you to define content that can be rendered in layouts. It provides a way to specify different parts of a layout view that can be overridden by views that use that layout.

// Example: Define a section in a view
@section Scripts {
    <script src="custom-script.js"></script>
}

84. What is an HTML Helper in ASP.NET MVC?

Answer: HTML Helpers in ASP.NET MVC are methods that generate HTML markup for controls and elements. They simplify the process of rendering HTML and can be used to generate form controls, links, and other HTML elements.

// Example: Using an HTML Helper to generate a textbox
@Html.TextBoxFor(model => model.PropertyName)

85. How can you handle errors in ASP.NET MVC?

Answer: Errors in ASP.NET MVC can be handled using custom error pages, the HandleError attribute, and the Application_Error event in Global.asax. Additionally, you can use try-catch blocks in controller actions.

// Example: Custom error page configuration in web.config
<customErrors mode="On" defaultRedirect="Error">
    <error statusCode="404" redirect="NotFound"/>
</customErrors>

86. What is the purpose of the ValidateAntiForgeryToken attribute in ASP.NET MVC?

Answer: The ValidateAntiForgeryToken attribute is used to prevent Cross-Site Request Forgery (CSRF) attacks. It ensures that the form submission originates from the correct site and protects against malicious form submissions.

// Example: Applying ValidateAntiForgeryToken attribute to an action method
[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult SubmitForm(FormViewModel model)
{
    // Process the form submission
    return RedirectToAction("Success");
}

87. Explain the concept of routing in ASP.NET MVC.

Answer: Routing in ASP.NET MVC is the process of mapping a URL to a specific controller action. It defines the pattern of the URL and extracts values from it to determine which action to invoke.

// Example: Adding a custom route in RouteConfig.cs
routes.MapRoute(
    name: "CustomRoute",
    url: "products/{category}/{id}",
    defaults: new { controller = "Products", action = "Details", id = UrlParameter.Optional }
);

88. What is the purpose of the TempData in ASP.NET MVC?

Answer: TempData is used to pass data from the current request to the next request, specifically during redirects. It’s useful when you need to show a message to the user after a redirect.

// Example: Setting TempData in a controller action
public ActionResult ProcessForm(FormViewModel model)
{
    TempData["SuccessMessage"] = "Form submitted successfully!";
    return RedirectToAction("Index");
}

89. What is the use of ChildActionOnly attribute in ASP.NET MVC?

Answer: The ChildActionOnly attribute restricts an action method so that it can only be called as a child action and not directly by a user request. This is useful for rendering partial views.

// Example: Applying ChildActionOnly attribute to an action method
[ChildActionOnly]
public ActionResult PartialViewWithData()
{
    var data = GetDataFromDatabase();
    return PartialView("_PartialView", data);
}

90. How do you implement authentication and authorization in ASP.NET MVC?

Answer: Authentication can be implemented using ASP.NET Identity, which provides features like user registration, login, and password management. Authorization can be achieved using attributes like Authorize to restrict access to certain actions or controllers.

// Example: Applying Authorize attribute to restrict access
[Authorize(Roles = "Admin")]
public ActionResult AdminDashboard()
{
    return View();
}

91. What is the role of the BundleConfig.cs file in an ASP.NET MVC application?

Answer: BundleConfig.cs is used to optimize the loading of CSS and JavaScript files. Bundling combines multiple files into a single file, reducing the number of HTTP requests required to load a webpage.

// Example: Registering bundles in BundleConfig.cs
public static void RegisterBundles(BundleCollection bundles)
{
    bundles.Add(new ScriptBundle("~/bundles/jquery").Include(
                "~/Scripts/jquery-{version}.js"));

    bundles.Add(new StyleBundle("~/Content/css").Include(
                "~/Content/site.css"));
}

92. Explain the purpose of Html.Partial and Html.RenderPartial in ASP.NET MVC.

Answer: Html.Partial and Html.RenderPartial are used to render a partial view within a view. Html.Partial returns a MvcHtmlString that can be stored in a variable, while Html.RenderPartial directly writes to the response output.

// Example: Using Html.Partial in a view
@{
    var partial = Html.Partial("_PartialView");
}

93. What is the difference between Html.RenderAction and Html.Action in ASP.NET MVC?

Answer: Html.RenderAction invokes a controller action and writes the result directly to the response output. Html.Action returns an MvcHtmlString that can be stored in a variable for later use.

// Example: Using Html.RenderAction in a view
@{ Html.RenderAction("RecentPosts", "Blog"); }

94. How can you handle errors in an ASP.NET MVC application?

Answer: Errors can be handled using the HandleError attribute, which can be applied at both controller and action levels. Additionally, custom error pages can be configured in the Web.config file.

// Example: Applying HandleError attribute to a controller
[HandleError]
public class HomeController : Controller
{
    // Controller actions
}

95. What is the purpose of the @section directive in Razor syntax?

Answer: The @section directive is used to define content that can be overridden in child views. It’s often used to specify placeholders for scripts, styles, or other content.

// Example: Defining a section in a layout view
@section Scripts {
    <script src="custom-script.js"></script>
}

96. Explain the concept of ViewModels in ASP.NET MVC.

Answer: ViewModels are custom classes that contain the data needed by a view. They are used to pass specific data from the controller to the view, helping to keep the views clean and focused on presentation logic.

// Example: Creating a ViewModel
public class ProductViewModel
{
    public int ProductId { get; set; }
    public string Name { get; set; }
    // Other properties...
}

97. What is the purpose of the Web.config file in an ASP.NET MVC application?

Answer: Web.config is the configuration file for an ASP.NET MVC application. It contains settings related to authentication, authorization, connection strings, error handling, and more.

<!-- Example: Connection string configuration in Web.config -->
<connectionStrings>
    <add name="DefaultConnection" connectionString="Data Source=.;Initial Catalog=MyDB;Integrated Security=True" providerName="System.Data.SqlClient" />
</connectionStrings>

98. What is the purpose of the ValidateAntiForgeryToken attribute in ASP.NET MVC?

Answer: The ValidateAntiForgeryToken attribute helps prevent cross-site request forgery (CSRF) attacks. It ensures that the form submission originated from the same application, protecting against malicious form submissions.

// Example: Applying ValidateAntiForgeryToken attribute to a controller action
[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult SubmitForm(FormViewModel model)
{
    // Action logic
}

99. How can you enable attribute-based routing in ASP.NET MVC?

Answer: Attribute-based routing allows you to define routes using attributes directly on the controller actions. It can be enabled by adding the MapMvcAttributeRoutes method in the RouteConfig.cs file.

// Example: Enabling attribute-based routing in RouteConfig.cs
public class RouteConfig
{
    public static void RegisterRoutes(RouteCollection routes)
    {
        routes.IgnoreRoute("{resource}.axd/{*pathInfo}");

        routes.MapMvcAttributeRoutes(); // Enable attribute-based routing

        // Other route configurations...
    }
}

100. Explain the purpose of the TempData in ASP.NET MVC.

Answer: TempData is used to pass data from the current request to the next request. It’s particularly useful for scenarios like redirecting after a form submission and displaying a success message.

// Example: Setting TempData in a controller action
public ActionResult SubmitForm(FormViewModel model)
{
    // Process form data

    TempData["SuccessMessage"] = "Form submitted successfully";
    return RedirectToAction("Index");
}