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.
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
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.
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.
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)
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 ()” })%>
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.
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.
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.
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().
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.
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
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.
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.
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)
 |
| Workday 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 ()” })%>
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.
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.
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.
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.
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().
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