What is the purpose of @RenderSection and how does it function? I understand what bundles do, but I have yet to figure out what this does and it's probably important.
@RenderSection("scripts", required: false)
Perhaps a small example on how to use it?
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
section block named scripts into a Token which contains an HtmlString, converts the result into a TextWriter, and writes the subsequent output to the HttpResponse as a handler in the ASP.NET Response Pipeline.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.
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)
}
Here the defination of Rendersection from MSDN
In layout pages, renders the content of a named section.MSDN
In _layout.cs page put
@RenderSection("Bottom",false)
Here render the content of bootom section and specifies false boolean property to specify whether the section is required or not.
@section Bottom{
This message form bottom.
}
That meaning if you want to bottom section in all pages, then you must use false as the second parameter at Rendersection method.
