October 13, 2018

Sreekanth B

Intelenet Global Services Most Frequently Asked ASP.NET MVC Interview Questions Answers

What are Code Blocks in Views?

Unlike code expressions that are evaluated and sent to the response, it is the blocks of code that are executed. This is useful for declaring variables which we may be required to be used later.

@{

int x = 123;

string y = “aa”;

}

What is the “HelperPage.IsAjax” Property?

The HelperPage.IsAjax property gets a value that indicates whether Ajax is being used during the request of the Web page.

How we can call a JavaScript function on the change of a Dropdown List in MVC?

Create a JavaScript method:

<script type=”text/javascript”>

function DrpIndexChanged() { }

</script>

Invoke the method:

<%:Html.DropDownListFor(x => x.SelectedProduct, new SelectList(Model.Customers, “Value”, “Text”), “Please Select a Customer”, new { id = “ddlCustomers”, onchange=” DrpIndexChanged ()” })%>
Intelenet Global Services Most Frequently Asked ASP.NET MVC Interview Questions Answers
Intelenet Global Services Most Frequently Asked ASP.NET MVC Interview Questions Answers

What is the meaning of Unobtrusive JavaScript?

This is a general term that conveys a general philosophy, similar to the term REST (Representational State Transfer). Unobtrusive JavaScript doesn’t intermix JavaScript code in your page markup.

Eg : Instead of using events like onclick and onsubmit, the unobtrusive JavaScript attaches to elements by their ID or class based on the HTML5 data- attributes.

What is the use of ViewModel in MVC?

ViewModel is a plain class with properties, which is used to bind it to strongly typed view. ViewModel can have the validation rules defined for its properties using data annotations.

What are Validation Annotations?

Data annotations are attributes which can be found in the “System.ComponentModel.DataAnnotations” namespace. These attributes will be used for server-side validation and client-side validation is also supported. Four attributes — Required, String Length, Regular Expression and Range are used to cover the common validation scenarios.

Why to use Html.Partial in MVC?

This method is used to render the specified partial view as an HTML string. This method does not depend on any action methods. We can use this like below –

@Html.Partial(“TestPartialView”)

Can you explain RenderBody and RenderPage in MVC?

RenderBody is like ContentPlaceHolder in web forms. This will exist in layout page and it will render the child pages/views. Layout page will have only one RenderBody() method. RenderPage also exists in Layout page and multiple RenderPage() can be there in Layout page.

What is ViewStart Page in MVC?

This page is used to make sure common layout page will be used for multiple views. Code written in this file will be executed first when application is being loaded.

Explain the methods used to render the views in MVC?

Below are the methods used to render the views from action -

View() — To return the view from action.

PartialView() — To return the partial view from action.

RedirectToAction() — To Redirect to different action which can be in same controller or in different controller.

Redirect() — Similar to “Response.Redirect()” in webforms, used to redirect to specified URL.

RedirectToRoute() — Redirect to action from the specified URL but URL in the route table has been matched.

What are the sub types of ActionResult?

ActionResult is used to represent the action method result. Below are the subtypes of ActionResult –

ViewResult

PartialViewResult

RedirectToRouteResult

RedirectResult

JavascriptResult

JSONResult

FileResult

HTTPStatusCodeResult

What are Non Action methods in MVC?

In MVC all public methods have been treated as Actions. So if you are creating a method and if you do not want to use it as an action method then the method has to be decorated with “NonAction” attribute as shown below –

[NonAction]

public void TestMethod()

{

// Method logic

}

How to change the action name in MVC?

“ActionName” attribute can be used for changing the action name. Below is the sample code snippet to demonstrate more –

[ActionName(“TestActionNew”)]

public ActionResult TestAction()

{

return View();

}

So in the above code snippet “TestAction” is the original action name and in “ActionName” attribute, name — “TestActionNew” is given. So the caller of this action method will use the name “TestActionNew” to call this action.

What is Html.RenderPartial?

Result of the method — “RenderPartial” is directly written to the HTML response. This method does not return anything (void). This method also does not depend on action methods. RenderPartial() method calls “Write()” internally and we have to make sure that “RenderPartial” method is enclosed in the bracket. Below is the sample code snippet –@{Html.RenderPartial(“TestPartialView”); }

What are the components required to create a route in MVC?

Name — This is the name of the route.

URL Pattern — Placeholders will be given to match the request URL pattern.

Defaults –When loading the application which controller, action to be loaded along with the parameter.

Why to use “{resource}.axd/{*pathInfo}” in routing in MVC?

Using this default route — {resource}.axd/{*pathInfo}, we can prevent the requests for the web resources files like — WebResource.axd or ScriptResource.axd from passing to a controller.

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