Top 30 interview questions and answers on ASP .Net MVC with a full explanation and code example
Question 1: What is ASP.NET MVC?
Answer:
ASP.NET MVC is a framework for building web applications using the Model-View-Controller architectural pattern. It separates an application into three main components: the model (data and business logic), the view (user interface), and the controller (handles user requests and updates the model).
Question 2: What are the advantages of using ASP.NET MVC?
Answer:
Some advantages of using ASP.NET MVC are:
- Separation of concerns: MVC enforces a clear separation between the model, view, and controller, making the code easier to maintain and test.
- Testability: The separation of concerns enables easier unit testing of each component.
- Extensibility: Developers can easily extend or customize various components of MVC to fit their application's needs.
- SEO-friendly URLs: MVC supports the creation of search engine-friendly URLs, improving the application's visibility.
- Supports multiple view engines: MVC allows the use of different view engines like Razor, WebForms, etc., providing flexibility in choosing the right one for the project.
Question 3: Explain the MVC architectural pattern.
Answer:
The MVC pattern separates an application into three components:
- Model: Represents the data and business logic of the application. It encapsulates the application's state and behavior.
- View: Displays the user interface to the user. It presents the data from the model in a specific format and sends user input back to the controller.
- Controller: Handles user requests, interacts with the model to update data, and selects the appropriate view to render the response.
Question 4: How does routing work in ASP.NET MVC?
Answer:
Routing maps the URLs of an application to specific controllers and actions. The routing engine examines the incoming URL and tries to match it with a predefined route pattern. If a match is found, the associated controller and action method are invoked.
Example: In the "RouteConfig.cs" file, you can define routes like this:
C#public class RouteConfig
{
public static void RegisterRoutes(RouteCollection routes)
{
routes.IgnoreRoute("{resource}.axd/{*pathInfo}");
routes.MapRoute(
name: "Default",
url: "{controller}/{action}/{id}",
defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }
);
}
}
Question 5: What is the role of a controller in ASP.NET MVC?
Answer:
The controller handles user requests, interacts with the model to retrieve or update data, and selects the appropriate view to render the response. It contains action methods that are responsible for processing the user's input and updating the model accordingly.
Example:
C#public class HomeController : Controller
{
public ActionResult Index()
{
return View();
}
}
Question 6: Explain the ViewData, ViewBag, and TempData in ASP.NET MVC. Answer:
- ViewData: ViewData is a dictionary that allows passing data from a controller to a view. It uses a string key-value pair to store data, but type casting is required in the view to access the values.
Example (Controller):
C#public ActionResult Index()
{
ViewData["Message"] = "Hello, world!";
return View();
}
Example (View):
html<p>@ViewData["Message"]</p>
- ViewBag: ViewBag is a dynamic wrapper around ViewData, providing a more convenient way to pass data from a controller to a view. It avoids the need for type casting in the view.
Example (Controller):
C#public ActionResult Index()
{
ViewBag.Message = "Hello, world!";
return View();
}
Example (View):
html<p>@ViewBag.Message</p>
- TempData: TempData is used to store data between multiple requests. It is useful when redirecting from one action to another. It internally uses session state or cookies to store data temporarily.
Example (Controller):
C#public ActionResult Action1()
{
TempData["Message"] = "Data from Action1";
return RedirectToAction("Action2");
}
public ActionResult Action2()
{
string message = TempData["Message"] as string;
return View((object)message);
}
Example (View):
html<p>@Model</p>
Question 7: What is the Razor view engine in ASP.NET MVC?
Answer:
Razor is a view engine used in ASP.NET MVC for creating dynamic web pages. It enables embedding server-side code within HTML markup, making it easier to generate dynamic content.
Example:
html+razor<p>Welcome, @Model.Name!</p>
Question 8: What is the difference between partial view and a view in ASP.NET MVC? Answer: A view represents a complete HTML page, while a partial view represents a reusable portion of a view. Partial views can be embedded in other views or rendered independently.
Example (Partial View):
html+razor<!-- _PartialView.cshtml --> <p>This is a partial view.</p>
Example (View):
html+razor<!-- View.cshtml --> <h1>My Page</h1> @Html.Partial("_PartialView")
Question 9: How do you pass data from a controller to a view?
Answer:
You can pass data from a controller to a view using ViewBag, ViewData, or strongly-typed models.
Example (Using ViewBag):
C#public ActionResult Index()
{
ViewBag.Message = "Hello, world!";
return View();
}
Example (Using ViewData):
C#public ActionResult Index()
{
ViewData["Message"] = "Hello, world!";
return View();
}
Example (Using Model):
C#public class MyViewModel
{
public string Message { get; set; }
}
public ActionResult Index()
{
var model = new MyViewModel { Message = "Hello, world!" };
return View(model);
}
Question 10: How do you handle form submissions in ASP.NET MVC?
Answer:
To handle form submissions in ASP.NET MVC, you can create an action method in the controller that accepts the form data as parameters. The action method is invoked when the form is submitted, and it can process the data and redirect to another view or perform other operations.
Example:
C#[HttpPost]
public ActionResult SubmitForm(string name, int age)
{
// Process form data
// Redirect or return a view
}
Question 11: What is the purpose of the @Html.Action() method in ASP.NET MVC?
Answer:
The @Html.Action() method is used to render the output of an action method within a view. It invokes the specified action method and renders its result as part of the current view.
Example:
html+razor<!-- Index.cshtml --> <div> @Html.Action("GetTime", "Home") </div>
Question 12: Explain the concept of model binding in ASP.NET MVC.
Answer:
Model binding is the process of mapping incoming request data to the parameters of an action method or properties of a model object. ASP.NET MVC automatically performs model binding based on the names and types of the incoming request data and the parameters of the action method.
Example (Action Method with Model Binding):
C#[HttpPost]
public ActionResult SaveData(Person person)
{
// Access properties of the Person model
// Save data to the database
// Redirect or return a view
}
Question 13: How can you enable attribute-based routing in ASP.NET MVC?
Answer:
Attribute-based routing allows you to define routes directly on the controller or action method using attributes. To enable attribute-based routing, you need to add the [Route] attribute to the controller or action methods and call the MapMvcAttributeRoutes() method in the RouteConfig.cs file.
Example (Enabling Attribute-Based Routing):
C#// RouteConfig.cs
public class RouteConfig
{
public static void RegisterRoutes(RouteCollection routes)
{
routes.IgnoreRoute("{resource}.axd/{*pathInfo}");
routes.MapMvcAttributeRoutes();
}
}
// HomeController.cs
[RoutePrefix("home")]
public class HomeController : Controller
{
[Route("index")]
public ActionResult Index()
{
// ...
}
}
Question 14: What is the purpose of the [Authorize] attribute in ASP.NET MVC?
Answer:
The [Authorize] attribute is used to restrict access to specific controller actions or entire controllers. It ensures that only authenticated users who meet the specified authorization requirements can access the decorated actions or controllers.
Example:
C#[Authorize]
public class HomeController : Controller
{
public ActionResult Index()
{
// This action requires authentication
}
}
Question 15: How can you handle errors and exceptions in ASP.NET MVC?
Answer:
ASP.NET MVC provides several ways to handle errors and exceptions:
- Custom Error Pages: You can configure custom error pages in the
web.configfile to display friendly error messages to users. - Global Error Handling: You can use the
Application_Errorevent in theGlobal.asax.csfile to handle unhandled exceptions and perform custom error handling logic. - HandleErrorAttribute: You can use the
[HandleError]attribute on controllers or action methods to specify a default error view. - Exception Filters: You can create custom exception filters by implementing the
IExceptionFilterinterface and applying them to controllers or action methods.
Question 16: What is the difference between TempData and ViewBag?
Answer:
TempDatais used to pass data between two consecutive requests. It stores data temporarily in session state or cookies and is accessible across different actions or controllers.ViewBagis used to pass data from a controller to a view during the same request. It stores data in the server's memory and is accessible within the same request and view.
Question 17: What are action filters in ASP.NET MVC?
Answer:
Action filters are attributes that can be applied to controllers or action methods to modify the behavior of the action execution pipeline. They can be used to perform tasks before or after an action method executes, such as logging, caching, authorization, validation, etc.
Question 18: How can you implement validation in ASP.NET MVC?
Answer:
ASP.NET MVC provides built-in validation mechanisms using data annotations, model validation attributes, and the ModelState object. By applying attributes like [Required], [StringLength], or creating custom validation attributes, you can perform server-side validation. The validation results can be checked in the controller using ModelState.IsValid or by using the ValidationSummary or ValidationMessage helpers in the view.
Example:
C#public class Person
{
[Required]
public string Name { get; set; }
[Range(18, 99)]
public int Age { get; set; }
}
[HttpPost]
public ActionResult Save(Person person)
{
if (ModelState.IsValid)
{
// Data is valid, perform further operations
}
else
{
// Data is invalid, show error messages
}
}
Question 19: What is the role of the BundleConfig class in ASP.NET MVC?
Answer:
The BundleConfig class is used to register bundles in an ASP.NET MVC application. Bundles are groups of static files like CSS and JavaScript files that can be combined and minified to reduce the number of HTTP requests made by the browser, improving performance.
Example (BundleConfig.cs):
C#public class BundleConfig
{
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/bootstrap.css",
"~/Content/site.css"));
}
}
Question 20: 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 data submitted to a controller action matches a dynamically generated anti-forgery token. If the tokens don't match, the action won't be processed.
Example:
C#[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult SaveData(Person person)
{
// Process form data
// Redirect or return a view
}
Question 21: What is the difference between ActionResult and ViewResult in ASP.NET MVC?
Answer:
ActionResultis the base class for all action results in ASP.NET MVC. It represents the result of an action method and can be used to return different types of results such asViewResult,RedirectResult,JsonResult, etc.ViewResultis a type ofActionResultthat returns a view to be rendered. It encapsulates the view name, model, and other view-related properties.
Question 22: How can you implement authentication and authorization in ASP.NET MVC?
Answer:
Authentication and authorization can be implemented in ASP.NET MVC using various methods such as Forms Authentication, Windows Authentication, and ASP.NET Identity. Forms Authentication involves creating a login form, validating user credentials, and issuing authentication tickets. Authorization can be achieved by using role-based or claims-based authorization mechanisms.
Question 23: What is the purpose of the @section directive in ASP.NET MVC views?
Answer:
The @section directive in ASP.NET MVC views is used to define a named section that can be rendered in a layout page. It allows individual views to provide content for specific sections defined in the layout page, such as a page title, scripts, stylesheets, etc.
Example (View):
html+razor@section Scripts { <script src="myscript.js"></script> }
Example (Layout Page):
html+razor<!DOCTYPE html> <html> <head> <!-- Head content --> </head> <body> <!-- Body content --> @RenderSection("Scripts", required: false) </body> </html>
Question 24: What is scaffolding in ASP.NET MVC?
Answer:
Scaffolding is a code generation technique in ASP.NET MVC that automates the creation of basic CRUD (Create, Read, Update, Delete) operations for a model. It generates the necessary controller actions, views, and other components to quickly build an application based on a data model.
Question 25: What is the purpose of the @Html.DisplayFor and @Html.EditorFor methods in ASP.NET MVC?
Answer:
@Html.DisplayForis used to render the value of a property from a model as read-only text. It applies the appropriate display template based on the data type of the property.@Html.EditorForis used to render an input element for a property from a model. It applies the appropriate editor template based on the data type of the property.
Example (DisplayFor):
html+razor<p>Name: @Html.DisplayFor(model => model.Name)</p>
Example (EditorFor):
html+razor<p>Name: @Html.EditorFor(model => model.Name)</p>
Question 26: How can you handle AJAX requests in ASP.NET MVC?
Answer:
To handle AJAX requests in ASP.NET MVC, you can create action methods that return PartialViewResult, JsonResult, or ActionResult with appropriate content. You can use AJAX helper methods like Ajax.BeginForm or make AJAX requests using JavaScript frameworks like jQuery.
Question 27: Explain the concept of areas in ASP.NET MVC.
Answer:
Areas in ASP.NET MVC provide a way to partition a large application into smaller, self-contained modules. Each area represents a separate section of the application with its own controllers, views, and other related components. Areas help organize the application's codebase and provide a logical separation of concerns.
Question 28: What is the difference between ViewBag and ViewData?
Answer:
ViewBagis a dynamic property that provides a convenient way to pass data from a controller to a view. It uses theViewBagobject to store and retrieve data, and the property values are resolved at runtime.ViewDatais a dictionary-like object that is used to pass data from a controller to a view. It uses theViewDatadictionary to store and retrieve data, and the property values are resolved at runtime.
Question 29: How can you implement caching in ASP.NET MVC?
Answer:
Caching in ASP.NET MVC can be implemented using various caching techniques such as Output Caching, Data Caching, and Fragment Caching. Output Caching allows you to cache the entire output of a controller action or a portion of it. Data Caching allows you to cache the results of expensive data operations. Fragment Caching allows you to cache specific portions of a view or partial view.
Question 30: What are the main components of the ASP.NET MVC framework?
Answer:
The main components of the ASP.NET MVC framework are:
- Model: Represents the application's data and business logic.
- View: Represents the user interface for displaying the data.
- Controller: Handles user requests, interacts with the model, and selects the appropriate view to render.
These were the final 10 questions and answers on ASP.NET MVC. I hope they provide you with a comprehensive understanding of the topic. Good luck with your interviews!
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