Razor #if inside <script> is rejected by VS11 - visual-studio

Is the following markup incorrect, or is it a bug in the Razor engine in MVC4? Either way, what's the best workaround?
The entire content of View1.cshtml is shown. It compiles fine, but the Intellisense error highlighting is annoying. (Included as an image so you can see how the syntax is rejected by VS11.)
Hote that the #: syntax (instead of <text></text>) isn't accepted either.

It's a little tricky to mix JavaScript with Razor. Personally, I find it easier to always separate these two guys by using either Razor #function or Razor custom #helper.
Here's a simple example:
<script type="text/javascript">
function btn_clicked() {
#generateMyJavaScript()
}
</script>
<a href="javascript:void(0)" onclick='btn_clicked()'>Click on me</a>
#functions {
private MvcHtmlString generateMyJavaScript()
{
string jsBuilder = string.Empty;
if (true)
jsBuilder = "alert('Hey!');";
return MvcHtmlString.Create(jsBuilder);
}
}

I noticed strange behavior of the syntax highlighter too. This is not really an answer but:
I try staying away from mixing model data into javascript. Although powerfull it is a bit spaghetti-like.
Also I try to have as little as possible tags in the html. I use js includes and jQuery $(document).ready(function () ... functions inside those.
There you can extract the JSON data from the data attributes and base javascript decisions on those.
(Wanted to write this as a comment but didn't find the way to do that, sorry for the debump)

Related

What replaced ClientScriptManager in MVC?

I'm converting an ASP.NET Forms app (that I didn't write) to an MVC 3 app. The ClientScriptManager is used in the old app. ClientScriptManager doesn't exist in MVC 3. What replaced ClientScriptManager? I've done enough reading to know that CSM has something to do with AJAX functionality in ASP.NET; it registers "sets" of js scripts and functions somewhat akin to how EditorTemplates work for sets of similar controls. I'm not necessarily looking to implement a CSM in MVC; I just want to know what practices Microsoft put in place that rendered CSM obsolete.
ASP.Net MVC was designed to give you complete control over the HTML and js, rather than having the framework render these for you, as with ASP.Net. So, nothing really "replaces" the ClientScriptManager. As a result, it is entirely up to you how you handle your js.
You can do something simple like include <script ...> tags to reference inline script or js files in your _Layout.cshtml file, or you could use some sort of JavaScript Loader like RequireJS or come up with your own scheme entirely using "Html Helpers" or something.
MVC 4 introduced the concept of bundling which lets you define collections of scripts as "bundles" and have MVC automatically minify and merge them together for you when you reference them in your Views like this :
#Scripts.Render("~/bundles/jquery")
Below is an example for rendering the JavaScript(Function) from Controller.
Controller
public ActionResult Index(int? id)
{
ViewBag.MyAlert = "<script type='text/javascript'>MyAlert();</script>";
}
View
<script src="Your Path" type="text/javascript"></script>
#Html.Raw(ViewBag.MyAlert)
JS
function MyAlert() {
alert('Hi');
}
Below is an example for rendering the JavaScript(File) from Controller.
protected override void OnActionExecuted(ActionExecutedContext filterContext)
{
StringBuilder sb = new StringBuilder();
sb.Append("<script src='Your Path' type='text/javascript'></script>");
filterContext.HttpContext.Response.Write(sb.ToString());
}
So using this approach you do not need to mentioned following code in View.
<script src="Your Path" type="text/javascript"></script>

MVC3 Html.BeginForm() with additional HTML

I am writing some code where I would like render a MVC BeginForm but to also include additional HTML.
For eg.
#using (Html.BeginMyCustomForm()) {
}
And this spits out
<form action="" etc>
PLUS
<input type="hidden" name="my-additional-field-i-always-want">
#Html.ValidationMessageFor(m => m)
Is this possible?
I know I'll be looking at some kind of extension or something most likely.
Hope this makes sense and thanks in advance!
It's not a good idea to include such things in an extension to BeginForm. The reason is that good design dictates that objects should do one thing. This is called the Single Responsibility Principle.
You now want your form object to also create inputs and validation.
Instead, use the MVC templating system and create a default template to use for your needs. You should also use Html.HiddenFor rather than using an input tag, unless there is some specific reason not to.
Another option is to use MVC Scaffolding to generate what you want.
More about Editor Templates http://bradwilson.typepad.com/blog/2009/10/aspnet-mvc-2-templates-part-1-introduction.html
More about Scaffolding http://blog.stevensanderson.com/2011/01/13/scaffold-your-aspnet-mvc-3-project-with-the-mvcscaffolding-package/
Maybe you can use something like this?
public static class FormExtensions
{
public static MvcForm BeginMyCustomForm(this HtmlHelper htmlHelper)
{
var form = htmlHelper.BeginForm();
htmlHelper.ViewContext.Writer.write( .... )
return form;
}
}

When in Editor Template, how can I put javascript in the head section?

I hava an editor template for, let's say, date:
#model DateTime
#section AdditionalJavaScript2
{
/* some js code */
}
#Html.TextBox("", Model.ToString("d.M.yyyy"), new { #class = "date" })
Now, I would like to put some js code into the HEAD section, but this doesn't work.
Of course, I have a this section in my layout.cshtml:
<head>
...
#RenderSection("AdditionalJavaScript2", required: false)
</head>
It works from the plain view, but not from partial view (editor template).
Why?
And, is there a workaround?
Thanks,
Igor
A partial-view does not use a template, it returns "raw" html to be included in your page (by Javascript). It does not have access to anything but the stream it returns itself.
Think of it like this: You typically call a partial view from Javascript/AJAX to get some new html. You get the return, and replace some DIV-tag. How can the system (FireFox, Chrome, ...) know, that there is some extra section of data that needs to replace something in the HEAD tag.
There are some workarounds:
Don't put the script in the HEAD
Add a parameter switch betweed the html and the script. You need to client-side calls, one to get the html, and one for the script. You include the calls to the partial-view on two locations on your page.
Separate the script and the html using some pre-defined tag like <!-- SEPERATOR -->, and let the calling code split the result, and put it in the correct position.

Declarative AJAX "Controls" in MVC

I want to create a reusable ajax control in MVC .NET using RAZOR.
my example is a simple ajax text box and list where the user filters the list by typing in the text box. on the first call i would render both the text box and the list using my razor view. on subsequent AJAX calls i would want to ONLY render the (now filtered) list.
idea 1: use #if statement to conditionally render code.
problem: razor does not seem to like conditionally written html. for example it errors when a <div> tag is not followed by a closing </div>.
idea 2: use #section tokens to create portions of my control and then call RenderSection within the same file as needed.
problem: razor does not allow RenderSection to call sections in the same page
i know i can conditionally render html as strings, but i wanted to take advantage of the legibility of the razor markup and keep with development protocols.
You should be able to output <div> tags in a Razor block without the corresponding </div> tag by surrounding it with <text>. The reason is that Razor uses the closing tag to know when to drag back into code-parsing mode:
#if (myCondition)
{
<text>
<div>
</text>
}
As for the Section stuff, you might be able to achieve what you want using Templated Razor Delegates, like this:
#{
Func<dynamic, object> b = #<strong>#item</strong>;
}
// ...
<span>This sentence is #b("In Bold").</span>
See Phil Haack's blog for a little more on this.

Razor Nested Layouts with Cascading Sections

I have an MVC3 site using Razor as its view engine. I want my site to be skinnable. Most of the possible skins are similar enough that they can derive from a shared master layout.
Therefore, I am considering this design:
However, I would like to be able to call RenderSection in the bottom layer, _Common.cshtml, and have it render a section that is defined in the top layer, Detail.cshtml. This doesn't work: RenderSection apparently only renders sections that are defined the next layer up.
Of course, I can define each section in each skin. For instance, if _Common needs to call RenderSection("hd") for a section defined in Detail, I just place this in each _Skin and it works:
#section hd {
#RenderSection("hd")
}
This results in some duplication of code (since each skin must now have this same section) and generally feels messy. I'm still new to Razor, and it seems like I might be missing something obvious.
When debugging, I can see the complete list of defined sections in WebViewPage.SectionWritersStack. If I could just tell RenderSection to look through the entire list before giving up, it would find the section I need. Alas, SectionWritersStack is non-public.
Alternatively, if I could access the hierarchy of layout pages and attempt execution of RenderSection in each different context, I could locate the section I need. I'm probably missing something, but I don't see any way to do this.
Is there some way to accomplish this goal, other than the method I've already outlined?
This is in fact not possible today using the public API (other than using the section redefinition approach). You might have some luck using private reflection but that of course is a fragile approach. We will look into making this scenario easier in the next version of Razor.
In the meantime, here's a couple of blog posts I've written on the subject:
http://blogs.msdn.com/b/marcinon/archive/2010/12/08/optional-razor-sections-with-default-content.aspx
http://blogs.msdn.com/b/marcinon/archive/2010/12/15/razor-nested-layouts-and-redefined-sections.aspx
#helper ForwardSection( string section )
{
if (IsSectionDefined(section))
{
DefineSection(section, () => Write(RenderSection(section)));
}
}
Would this do the job ?
I'm not sure if this is possible in MVC 3 but in MVC 5 I am able to successfully do this using the following trick:
In ~/Views/Shared/_Common.cshtml write your common HTML code like:
<!DOCTYPE html>
<html lang="fa">
<head>
<title>Skinnable - #ViewBag.Title</title>
</head>
<body>
#RenderBody()
</body>
</html>
In ~/Views/_ViewStart.cshtml:
#{
Layout = "~/Views/Shared/_Common.cshtml";
}
Now all you have to do is to use the _Common.cshtml as the Layout for all the skins. For instance, in ~/Views/Shared/Skin1.cshtml:
#{
Layout = "~/Views/Shared/_Common.cshtml";
}
<p>Something specific to Skin1</p>
#RenderBody()
Now you can set the skin as your layout in controller or view based on your criteria. For example:
public ActionResult Index()
{
//....
if (user.SelectedSkin == Skins.Skin1)
return View("ViewName", "Skin1", model);
}
If you run the code above you should get a HTML page with both the content of Skin1.cshtml and _Common.cshtml
In short, you'll set the layout for the (skin) layout page.
Not sure if this will help you, but I wrote some extension methods to help "bubble up" sections from within partials, which should work for nested layouts as well.
Injecting content into specific sections from a partial view ASP.NET MVC 3 with Razor View Engine
Declare in child layout/view/partial
#using (Html.Delayed()) {
<b>show me multiple times, #Model.Whatever</b>
}
Render in any parent
#Html.RenderDelayed();
See the answer link for more use-cases, like only rendering one delayed block even if declared in a repeating view, rendering specific delayed blocks, etc.

Resources