ASP.NET MVC Interview Question
1) What is ASP.NET MVC?
ASP.NET MVC is a web application Framework. It is light weight and highly testable Framework. MVC separates application into three components — Model, View and Controller.
2)
Can you explain Model, Controller and View in MVC?
Model — It’s a business
entity and it is used to represent the application data.
Controller — Request sent by
the user always scatters through controller and it’s responsibility is to
redirect to the specific view using View() method.
View — It’s the
presentation layer of MVC.
3)Explain
the new features added in version 4 of MVC (MVC4)?
Following
are features added newly –
→Asynchronous
controller task support.
→Bundling the
java scripts.
→Segregating the
configs for MVC routing, Web API, Bundle etc.
→Mobile templates
→Added ASP.NET
Web API template for creating REST based services.
→Asynchronous
controller task support.
→Bundling the
java scripts.
→Segregating the
configs for MVC routing, Web API, Bundle etc.
4)Can
you explain the page life cycle of MVC?
Below
are the processed followed in the sequence -
→App
initialization
→Routing
→Instantiate and
execute controller
→Locate and
invoke controller action
→Instantiate and
render view.
5)
What are the advantages of MVC over ASP.NET?
→Provides a
clean separation of concerns among UI (Presentation layer), model (Transfer
objects/Domain Objects/Entities) and Business Logic (Controller).
→Easy to UNIT
Test.
→Improved
reusability of model and views. We can have multiple views which can point to
the same model and vice versa.
→Improved
structuring of the code.
6)
What is Separation of Concerns in ASP.NET MVC?
It’s
is the process of breaking the program into various distinct features which
overlaps in functionality as little as possible. MVC pattern concerns on
separating the content from presentation and data-processing from content.
7)
What is Razor View Engine?
Razor
is the first major update to render HTML in MVC 3. Razor was designed
specifically for view engine syntax. Main focus of this would be to simplify
and code-focused templating for HTML generation. Below is the sample of using
Razor:
@model MvcMusicStore.Models.Customer
@{ViewBag.Title = “Get Customers”;}
<div class=”cust”>
<h3><em>@Model.CustomerName</em> </h3>
8)
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.
9)
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.
10)
What you mean by Routing in MVC?
Routing
is a pattern matching mechanism of incoming requests to the URL patterns which
are registered in route table. Class — “UrlRoutingModule” is used for the same process.
11)
What are Actions in MVC?
Actions
are the methods in Controller class which is responsible for returning the view
or json data. Action will mainly have return type — “ActionResult”
and it will be invoked from method — “InvokeAction()” called by controller.
12)
What is Attribute Routing in MVC?
ASP.NET
Web API supports this type routing. This is introduced in MVC5. In this type of
routing, attributes are being used to define the routes. This type of routing
gives more control over classic URI Routing. Attribute Routing can be defined
at controller level or at Action level like –
[Route(“{action = TestCategoryList}”)] — Controller
Level
[Route(“customers/{TestCategoryId:int:min(10)}”)] — Action Level
13)
How to enable Attribute Routing?
Just
add the method — “MapMvcAttributeRoutes()” to enable attribute routing as shown below
public
static void RegistearRoutes(RouteCollection routes)
{
routes.IgnoareRoute(“{resource}.axd/{*pathInfo}”);
//enabling
attribute routing
routes.MapMvcAttributeRoutes();
//convention-based
routing
routes.MapRoute
(
name:
“Default”,
url:
“{controller}/{action}/{id}”,
defaults:
new { controller = “Customer”, action = “GetCustomerList”, id =
UrlParameter.Optional }
);
}
14)
Explain JSON Binding?
JavaScript
Object Notation (JSON) binding support started from MVC3 onwards via the new
JsonValueProviderFactory, which allows the action methods to accept and
model-bind data in JSON format. This is useful in Ajax scenarios like client
templates and data binding that need to post data back to the server.
15)
Explain Dependency Resolution?
Dependency
Resolver again has been introduced in MVC3 and it is greatly simplified the use
of dependency injection in your applications. This turn to be easier and useful
for decoupling the application components and making them easier to test and
more configurable.
16)
Explain Bundle.Config in MVC4?
“BundleConfig.cs” in MVC4 is used to register the
bundles by the bundling and minification system. Many bundles are added by
default including jQuery libraries like — jquery.validate, Modernizr, and default CSS references.
17)
How route table has been created in ASP.NET MVC?
Method — “RegisterRoutes()”
is used for registering the routes which will be added in
“Application_Start()” method of global.asax file, which is fired when the
application is loaded or started.
18)
Which are the important namespaces used in MVC?
Below
are the important namespaces used in MVC -
System.Web.Mvc
System.Web.Mvc.Ajax
System.Web.Mvc.Html
System.Web.Mvc.Async
19)
What is ViewData?
Viewdata
contains the key, value pairs as dictionary and this is derived from class — “ViewDataDictionary“.
In action method we are setting the value for viewdata and in view the value
will be fetched by typecasting.
20)
What is the difference between ViewBag and ViewData in MVC?
ViewBag
is a wrapper around ViewData, which allows to create dynamic properties.
Advantage of viewbag over viewdata will be –
In
ViewBag no need to typecast the objects as in ViewData.
ViewBag
will take advantage of dynamic keyword which is introduced in version 4.0. But
before using ViewBag we have to keep in mind that ViewBag is slower than
ViewData.
21)
Explain TempData in MVC?
TempData
is again a key, value pair as ViewData. This is derived from
“TempDataDictionary” class. TempData is used when the data is to be used in two
consecutive requests, this could be between the actions or between the
controllers. This requires typecasting in view.
22)
What are HTML Helpers in MVC?
HTML
Helpers are like controls in traditional web forms. But HTML helpers are more
lightweight compared to web controls as it does not hold viewstate and events.
HTML
Helpers returns the HTML string which can be directly rendered to HTML page.
Custom HTML Helpers also can be created by overriding “HtmlHelper” class.
23)
What are AJAX Helpers in MVC?
AJAX
Helpers are used to create AJAX enabled elements like as Ajax enabled forms and
links which performs the request asynchronously and these are extension methods
of AJAXHelper class which exists in namespace — System.Web.Mvc.
24)
What are the options can be configured in AJAX helpers?
Below
are the options in AJAX helpers –
Url — This is the
request URL.
Confirm — This is used to
specify the message which is to be displayed in confirm box.
OnBegin — Javascript method
name to be given here and this will be called before the AJAX request.
OnComplete — Javascript
method name to be given here and this will be called at the end of AJAX
request.
OnSuccess — Javascript
method name to be given here and this will be called when
AJAX request is successful.
OnFailure — Javascript
method name to be given here and this will be called when AJAX request is
failed.
UpdateTargetId — Target element
which is populated from the action returning HTML.
25)
What is Layout in MVC?
Layout
pages are similar to master pages in traditional web forms. This is used to set
the common look across multiple pages. In each child page we can find — /p>
@{
Layout
= “~/Views/Shared/TestLayout1.cshtml”;
}
This
indicates child page uses TestLayout page as it’s master page.
26)
Explain Sections is MVC?
Section
are the part of HTML which is to be rendered in layout page. In Layout page we
will use the below syntax for rendering the HTML –
@RenderSection(“TestSection”)
And
in child pages we are defining these sections as shown below –
@section
TestSection{
<h1>Test
Content</h1>
}
If
any child page does not have this section defined then error will be thrown so
to avoid that we can render the HTML like this –
@RenderSection(“TestSection”,
required: false)
27)
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.
28)
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.
29)
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.
30)
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
31)
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
}
32)
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.
33)
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”;
}
34)
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.
35)
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 ()” })%>
36)
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.
37)
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”)
38)
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”); }
39)
What is RouteConfig.cs in MVC 4?
“RouteConfig.cs” holds the routing configuration for
MVC. RouteConfig will be initialized on Application_Start event registered in
Global.asax.
40)
What are Scaffold templates in MVC?
Scaffolding
in ASP.NET MVC is used to generate the Controllers,Model and Views for create,
read, update, and delete (CRUD) functionality in an application. The
scaffolding will be knowing the naming conventions used for models and
controllers and views.
41)
Explain the types of Scaffoldings.
Below
are the types of scaffoldings –
Empty
Create
Delete
Details
Edit
List
42)
Can a view be shared across multiple controllers? If Yes, How we can do that?
Yes,
we can share a view across multiple controllers. We can put the view in the
“Shared” folder. When we create a new MVC Project we can see the Layout page
will be added in the shared folder, which is because it is used by multiple
child pages.
43)
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.
44)
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.
45)
Can we add constraints to the route? If yes, explain how we can do it?
Yes
we can add constraints to route in following ways –
Using
Regular Expressions
Using
object which implements interface — IRouteConstraint.
46)
What are the possible Razor view extensions?
Below
are the two types of extensions razor view can have –
.cshtml — In C#
programming language this extension will be used.
.vbhtml — In VB
programming language this extension will be used.
47)
What is PartialView in MVC?
PartialView
is similar to UserControls in traditional web forms. For re-usability purpose
partial views are used. Since it’s been shared with multiple views these are
kept in shared folder. Partial Views can be rendered in following ways –
Html.Partial()
Html.RenderPartial()
48)
How we can add the CSS in MVC?
Below
is the sample code snippet to add css to razor views –
<link
rel=”StyleSheet” href=”/@Href(~Content/Site.css”)” type=”text/css”/>
49)
Can I add MVC Testcases in Visual Studio Express?
No.
We cannot add the test cases in Visual Studio Express edition it can be added
only in Professional and Ultimate versions of Visual Studio.
50)
What is the use .Glimpse in MVC?
Glimpse
is an open source tool for debugging the routes in MVC. It is the client side
debugger. Glimpse has to be turned on by visiting to local url link -
