What is @RenderSection in asp.net MVC

Suppose if I have GetAllEmployees.cshtml

<h2>GetAllEmployees</h2>

<p>
    <a asp-action="Create">Create New</a>
</p>
<table class="table">
    <thead>
         // do something ...
    </thead>
    <tbody>
       // do something ...
    </tbody>
</table>

   //Added my custom scripts in the scripts sections

@section Scripts
    {
    <script src="~/js/customScripts.js"></script>
    }

And another view "GetEmployeeDetails.cshtml" with no scripts

<h2>GetEmployeeByDetails</h2>

@Model.PageTitle
<p>
    <a asp-action="Create">Create New</a>
</p>
<table class="table">
    <thead>
       // do something ... 
    </thead>
    <tbody>
       // do something ...
    </tbody>
</table>

And my layout page "_layout.cshtml"

@RenderSection("Scripts", required: true)

So, when I navigate to GetEmployeeDetails.cshtml. I get the error that there is no section scripts to be rendered in GetEmployeeDetails.cshtml. If I change the flag in @RenderSection() from required : true to ``required : false`. It means render the scripts defined in the @section scripts of the views if present.Else, do nothing. And the refined approach would be in _layout.cshtml

@if (IsSectionDefined("Scripts"))
    {
        @RenderSection("Scripts", required: true)
    }

Supposing that:

1. You have a _Layout.cshtml view like this.

<html>
    <body>
        @RenderBody()
       
    </body>
    <script type="text/javascript" src="~/lib/layout.js"></script>
    @RenderSection("scripts", required: false)
</html>

2. You have Contacts.cshtml.

@section Scripts{
    <script type="text/javascript" src="~/lib/contacts.js"></script>

}
<div class="row">
    <div class="col-md-6 col-md-offset-3">
        <h2>    Contacts</h2>
    </div>
</div>

3. You have About.cshtml.

<div class="row">
    <div class="col-md-6 col-md-offset-3">
        <h2>    Contacts</h2>
    </div>
</div>

On your layout page, if required is set to false: @RenderSection("scripts", required: false), when the page renders and the user is on the about page, contacts.js won't render.

    <html>
        <body><div>About<div>             
        </body>
        <script type="text/javascript" src="~/lib/layout.js"></script>
    </html>

If required is set to true: @RenderSection("scripts", required: true), When page renders and user is on the About page, contacts.js still gets rendered.

<html>
    <body><div>About<div>             
    </body>
    <script type="text/javascript" src="~/lib/layout.js"></script>
    <script type="text/javascript" src="~/lib/contacts.js"></script>
</html>

IN SHORT, when set to true, whether you need it or not on other pages, it will get rendered anyhow. If set to false, it will render only when the child page is rendered.


If you have a _Layout.cshtml view like this

<html>
    <body>
        @RenderBody()
        @RenderSection("scripts", required: false)
    </body>
</html>

then you can have an index.cshtml content view like this

@section scripts {
     <script type="text/javascript">alert('hello');</script>
}

the required indicates whether or not the view using the layout page must have a scripts section

Tags:

Asp.Net Mvc

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