I have a _Layout.cshtml file that contains the following line.
#RenderSection("Scripts", required: false)
And then I have a StorageLayout.cshtml file that specifies _Layout.cshtml as the layout file. StorageLayout.cshtml defines the MainMenu section and contains #RenderBody().
But then my page that uses StorageLayout.cshtml as the layout file gives me an error:
InvalidOperationException: The following sections have been defined but have not been rendered by the page at '/Pages/Shared/_StorageLayout.cshtml': 'Scripts'. To ignore an unrendered section call IgnoreSection("sectionName").
I'm not sure I understand this. The Scripts section is explicitly not required, so why is it an error? And, for that matter, what would be the correct way to implement this section in nested layout files?
required is set to false, which means the section is optional.If the section is not optional, every content page that references the layout page must use the #section directive to define the section and provide content:-
#section Scripts{
// content here
}
In some cases, you might want to make a section optional, but you want to provide some default content in the event that the content page didn't provide anything for the section. You can use the IsSectionDefined method for this:-
#if(IsSectionDefined("OptionalSection"))
{
#RenderSection("OptionalSection")
}
else
{
// default content
}
Any sections defined in the master layout should also be redefined in child layouts:-
_MasterLayout.cshtml
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8" />
<title></title>
<link href="/css/site.css" rel="stylesheet" type="text/css" />
</head>
<body>
#RenderBody()
#RenderSection("scripts", required:false)
</body>
</html>
_ChildLayout.cshtml
#{
Layout = "/_MasterLayout";
}
<div class="main-content-two-col">
#RenderBody()
</div>
#section scripts {
#RenderSection("scripts", required: false)
}
I think this would help resolve your issue.
Related
I'm making a simple site with bootstrap and .net core mvc (v3.0). Because most of the pages reuse the bootstrap container, I decided to put that in the layout file, so that I wouldn't be repeating the same setup everywhere.
This has the downside that if a view needs fixed elements, those end up getting fixed to the container, not the viewport.
I'm wondering if it's possible to call some sort of syntax inside the view.cshtml file that could cause a section to be rendered in the _Layout.cshtml file (sorry if this has been answered, but I wasn't sure what to search for).
For instance
_Layout.cshtml
#using Microsoft.Extensions.Hosting
#inject Microsoft.AspNetCore.Hosting.IWebHostEnvironment _environment
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>#ViewData["Title"]</title>
</head>
<body>
#* this div only gets rendered based on logic inside the view*#
<div id="conditionalViewDiv">
</div>
<div class="content container-fluid pl-0 pr-0 moveable" id="containerMain">
<main role="main">
#RenderBody()
</main>
</div>
#RenderSection("Scripts", required: false)
</body>
</html>
and then in SomeView.cshtml
#{
ViewData["Title"] = "title";
Layout = "~/Views/Shared/_Layout.cshtml";
}
#MadeUpRenderCommand("conditionalViewDiv")
#*other view stuff*#
Thank you for any help.
According to the docs, View components are intended anywhere you have reusable rendering logic, similar to partial views, but they're much more powerful. The main difference is when you use partial view you still have dependency on controller while in View Component you don't need a controller. So there is a separation of concern.
A view component is a C# class that provides a partial view
with the data that it needs, independently from the parent view and the action that renders it.
Good enlightening examples can be found, particularly:
https://www.c-sharpcorner.com/article/working-with-view-components-in-asp-net-core-mvc/
https://jakeydocs.readthedocs.io/en/latest/mvc/views/view-components.html
Hope this helped.
Looking at some Razor views, I see a lot of times where a <style> tag is added directly in a view (CSHTML) file.
This seems to work fine, but in fact it adds the <style> tag inside the <body> tag, while it should generally be inside the <head> tag.
How would you some inline CSS to a single razor page so that it appears within the <head> tag? Is there a preferred way?
Like this:
Shared/_Layout.cshtml
<!DOCTYPE html>
<html>
<head>
...
#RenderSection("HeadStyles", required: false)
</head>
<body>
...
</body>
</html>
Home/Index.cshtml or whatever other view you need to do this in
#section HeadStyles {
<style>
.custom-style { color: red; }
</style>
}
The reason why inclusion of <style> tags is not recommended inside <body> is because of causing FOUC.
But if your <style> tag applies to content that's after it in DOM, that risk is null.
No browser currently in use has any trouble parsing <style> tags placed in <body>.
Technically, when the browser meets a <style> tag in DOM it:
pauses rendering
reconstructs CSSOM to include the new declarations
rebuilds the already rendered DOM (this is where FOUC happens, if)
carries on with rendering
best variant is -
<html>
<head>
<link rel="stylesheet" href="styles.css">
</head>
<body>
<!-- here is page content -->
<script src="scripts.js" type="text/javascript"></script>
</body>
</html>
in this case browser will load in this sequence
styles
content (which will be already styled)
scripts (which will not slow down page rendering in case if scipts are not so little)
This question already has answers here:
how to add script src inside a View when using Layout
(4 answers)
Closed 4 years ago.
Suppose I have a view called Login.cshtml, which I need to load these:
<link href="~/css/particle.css" rel="stylesheet" />
<script src="~/js/particle-js/particles.min.js"></script>
<script src="~/js/particle-js/app.js"></script>
In my application I have also _Layout.cshtml which contains the basic script to load for each, page. How can I load the script and css above in the when the user access to Login.cshtml view, as happen in _Layout.cshtml?
What I learned is the existence of #section, but I don't if is the best practive to do this, someone could suggest me how to do it properly?
Thanks in advance.
Section seems to be the appropriate solution for this use case.
So you will use the RenderSection method in your layout cshtml file. For example, if you want to include some static resources inside the head section of the document, you will create a new section in the head element of your layout
<head>
#RenderSection("PageCss",required:false)
</head>
<body>
<div>
#RenderBody()
#RenderSection("scripts", required: false)
</div>
</body>
and in your view(Login.cshtml), you will add the static resources through this specific section.
#section PageCss
{
<link href="~/css/particle.css" rel="stylesheet" />
<script src="~/js/particle-js/particles.min.js"></script>
<script src="~/js/particle-js/app.js"></script>
}
#section PageCss
{
<script src="~/js/anotherSciptWhichDoesNotBlockRendering.js"></script>
}
When razor executes the code, it will render the correct html.
You may create more than one section and use it as needed.
Consider using the async and defer attributes on script tag as appropriate to prevent render blocking script download/execution behavior.
I try to understand how works sections in Razor views. I have 2 layout files: _Layout.cshtml and _LayoutChild.cshtml which use the first layout inside. I try to declare sections in _Layout.cshtml and render it in the same file. Markup not appears but when I declare section in _LayoutChild.cshtml everything works. See example below:
_Layout.cshtml:
<!DOCTYPE html>
<html>
<head>
#RenderSection("A", false)
</head>
<body>
#section A{
<script>
alert("I'm in Layout!");
</script>
}
</body>
</html>
_LayoutChild.cshtml
#{
Layout = "_Layout";
}
#section A{
<script>
alert("I'm in LayoutChild!");
</script>
}
I understand that declaring section in the same file looks strange but I would like to know why it don't work?
While developing web site or application. Every page have some common section like header, footer, sidebar etc. Write and maintain these on every page is a hard job. So, we need a way to put them in one single place. Luckily in MVC we have Layout concept for this. We put all the common code in it and changing content in Views which will render in layout where we call #RenderBody() method.
Why we need sections ?
Some time we wanted to show specific content on some specific pages like newletters only show on blogs and home page, top news or some advertising banners on specific pages. For these type of scenarios sections rescue us in MVC.
How we can use section ?
We need to follow these two steps to used sections in MVC.
Declare Section in Layout, give it a name and tell is it required on
every page or not.
Define it in view
When views render then section content also added where we declare the section.
Code Example
1. Most of the time we need some specific javascript code for view. So we can do it like this
_Layout.cshtml
#RenderSection("scripts", required: false)
view.cshtml
#section scripts{
<script>
alert("I'm in Layout!");
</script>
}
2. News Letter example
_Layout.cshtml
#RenderSection("newletter", required: false)
view.cshtml
#section newletter{
<h3> New Letter </h3>
... rest of the html ...
}
I would like my default.aspx to use masterpage but have a different body than the rest of my webpages is this possible? Basically I want my default.aspx to have a background image for the entire page but still use the masterpage because I have menu and things I would like to use on that page as well. Is this possible?
You can define the styles and everything for a particular page in Content Page and not Master Page. In your case, if you want a separate styles and background for default.aspx, you can define those styles in default.aspx page.
inside of default.aspx do
<style>
BODY { background-image: url(....image here ....);}
</style>
I know it is not the nicest pattern but... cmon, masterpages
You can inline it on default.aspx
<style>
body{
/*Background stuff here */
}
</style>
or have an if on your master page
#if(currentpage == "home")
<div id="background">
</div>
#endif
or
#if(currentpage == "home")
<body style="background-stuff-here">
#else
<body>
#endif
Put these lines in you master page head section
<head>
<link type="text/css" rel="stylesheet" href="/styles/common1.css" />
<script type="text/javascript" src="/scripts/common1.js"></script>
<asp:contentplaceholder id="ExtraStylesAndScripts" runat="server" />
</head>
And these lines to you default page
<asp:content contentplaceholderid="ExtraStylesAndScripts" runat="server">
<link type="text/css" rel="stylesheet" href="/styles/extra1.css" />
<link type="text/css" rel="stylesheet" href="/styles/extra2.css" />
<script type="text/javascript" src="/scripts/extra1.js"></script>
<script type="text/javascript" src="/scripts/extra2.js"></script>
</asp:content>
Now you are free to set different page style for different content pages.
You can change background or other appearance in "styles/extra1.css" files.
A very simple solution would be a MultiView and pass in something like an enum object telling the master page what View to display. If you in the future need to add a different design for another page you can just add a View.