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Extend HiddenFor Templates in ASP.NET MVC

I thought Html.HiddenFor could use Templates like Html.DisplayFor or Html.EditorFor. Unfortunately the method doesn't accept a TemplateName like the others.
I know, the workaround would be to use a DisplayFor/EditorFor Template which has HiddenFors. But I would like to find out how to extend the Html.HiddenFor method. Anyone?
Regards

Seems like you are mislead by wrong analogy. HiddenFor corresponds exactly to the <input type="hidden"/> tag. Just like TextBoxFor, CheckBoxFor etc. These methods are not designed to use templates. DisplayFor/EditorFor on the other side are specially created to be used with templates defined in the project. Thus what you are asking for is not possible out-of-the-box.
However you can always define your own overload for HiddenFor with whatever set of parameters and whatever logic you might require.

There is an overload which accept additional parameter - htmlAttributes. And you can use it for add some attributes to the result tag.
Also the second way is to create razor partial view in one of the folders
~/Areas/AreaName/Views/ControllerName/DisplayTemplates/TemplateName.cshtml
~/Areas/AreaName/Views/Shared/DisplayTemplates/TemplateName.cshtml
~/Views/ControllerName/DisplayTemplates/TemplateName.cshtml
~/Views/Shared/DisplayTemplates/TemplateName.cshtml
with name HiddenInput.cshtml

Here's what you do, you create it as an editor template, because as Andre pointed out, HiddenFor is equivalent to the helper methods like TextBoxFor and CheckboxFor.
It's likely that you'll want to have an actual editor too, so place your real editor under ~/Shared/EditorTemplates. We're going to put our "hidden editor" under the controller you wish to use it on.
~/Views/ControllerName/EditorTemplates/ModelName.cshtml
Lets say we have a Person model.
public class Person
{
public string First { get; set; }
public string Last { get; set; }
}
We'll create a partial view.
#Model Person
#Html.HiddenFor(p => p.First);
#Html.HiddenFor(p => p.Last);
And then we'll pretend we have a model that contains a Person as a property. From our main view, we call our "hidden editor" like so.
#Model Foo
#Html.EditorFor(f => f.Person)
Easy peasy lemon squeezy. A bit hacky, but it works like a charm.

How can I insert HTML tags in C# string property?

Not sure how if it is possible, but I have this in a class:
public string TextNotIncluded
{
get
{
return ("which is <u>not</u> included in the Quote");
}
}
The <u> and </u> are being displayed in my view, rather than the word not being underlined. I am not familiar with C#.
Can anyone provide a quick answer?
Thanks.
Edit:
I am just calling this in my view thusly: #MyClass.TextNotIncluded. Wrapping it with #Html.Raw is not efficient in my case because I have this sprinkled throughout dozens of views.

There's nothing fundamentally wrong with doing that but it probably won't render the way you're expecting.
You can use #Html.Raw as others have suggested, but I think it's better to explicitly declare your model in such a way as to indicate that it may contain html. You probably want to use the MvcHtmlString class for this instead:
public MvcHtmlString TextNotIncluded
{
get { return MvcHtmlString.Create("which is <u>not</u> included in the Quote"); }
}
Then in your view you can just use:
#Model.TextNotIncluded

If you're using Razor, strings are HTML-encoded by default - you'll need to use Html.Raw to turn off the encoding:
#Html.Raw(x.TextNotIncluded)
In the ASPX engine, you would use <%= %>
<%= x.TextNotIncluded %> - this gives you the raw text
<%: x.TextNotIncluded %> - this HTML-encodes your text - you don't want this.

To output raw HTML, use the Raw HTML helper:
#Html.Raw(TextNotIncluded)
This helper doesn't HTML encode the input, so be careful when using it.

You need to HTML encode the string. Most are recommending the MVC approach, but I would make it more independent of the presentation layer.
public string TextNotIncluded {
get {
return System.Web.HttpUtility.HtmlEncode("which is <u>not</u> included in the Quote");
}
}

You can use either
#Html.Raw(Model.TextNotIncluded)
or
#MvcHtmlString.Create(Model.TextNotIncluded)
in your view.
But it would be better to alter the return type of the property:
public MvcHtmlString TextNotIncluded
{
get
{
return MvcHtmlString.Create("which is <u>not</u> included in the Quote");
}
}

ASP.Net MVC3 - Pass razor markup as a parameter

I have a helper called EditableArea which provides a user with a runtime-editable div (via JS). EditableArea helper checks if an editable area (not related to MVC's Area) with the specified ID exists in the DB, if so then it renders the area's HTML, otherwise it displays the default markup specified as a parameter of the helper:
#Html.EditableArea(someId, "<p>Click to edit contents</p>")
It all works ok, but I'd like to change it so that the default markup is specified not as a string but in razor syntax, something like:
#using (Html.EditableArea(someId))
{
<p>Click to edit contents</p>
}
Or something similar, like the way #sections work in MVC3.
How can I achieve that?
I can make an IDisposable which in its Dispose closes the TagBuilder, etc., but using this approach the markup will still be rendered (I can clear the rendered contents in the Dispose() but the code block would still run unnecessarily, which I'd like to avoid).
Is there some other way to pass a razor block to the helper, which may or may not be actually rendered?

Here's an example I use to render jQuery Template markup by passing in a template Id and razor-style syntax for the template itself:
public static MvcHtmlString jQueryTmpl(this HtmlHelper htmlHelper,
string templateId, Func<object, HelperResult> template)
{
return MvcHtmlString.Create("<script id=\"" + templateId +
"\" type=\"x-jquery-tmpl\">" + template.Invoke(null) + "</script>");
}
and this would be called with
#Html.jQueryTmpl("templateId", #<text>any type of valid razor syntax here</text>)
Basically just use Func<object, HelperResult> as your parameter and template.Invoke(null) (with arguments if necessary) to render it. Obviously you can skip the call to .Invoke() to avoid rendering the "default" markup.

Just to expand on the accepted answer, as it took me quite a while to resolve a similar problem and this is the question which popped up. What I really need was a #helper, which would accept razor text, as the template should contain quite some code. I played around for a long while trying to use several versions of type #helper item(Func<object, HelperResult> input), which I found on the web, with no success. Therefore I went for an approach like:
namespace project.MvcHtmlHelpers
{
public static class HelperExtensions
{
public static MvcHtmlString RazorToMvcString(this HtmlHelper htmlHelper, Func<object, HelperResult> template)
{
return MvcHtmlString.Create(template.Invoke(null).ToString());
}
}
}
and
#project.MvcHtmlHelpers
#helper item(other input, MvcHtmlString content)
{
<div class="item">
...other stuff...
<div class="content">
#content
</div>
</div>
}
and use this via
#item(other input, #Html.RazorToMvcString(#<text>this is a test</text>))
Now I can use the helper template for both Razor input, but I can also drop in partial views, which is handy at some points. As I am no expert there might be better options, but it seems like a flexible approach to me.

In case you're wondering this is how to do it in asp.net core 3.1
#{
void TemplateFunc(Func<object, IHtmlContent> template)
{
<div>#template(null)</div>
}
}
Then in markup you can use it as
<div>
#{TemplateFunc(#<div>123</div>);}
</div>

Taking this further, it is possible to pass the markup directly to a helper, without an extension method.
#helper HelperWithChild(Func<object, HelperResult> renderChild)
{
<div class="wrapper">
#renderChild(this)
</div>
}
#HelperWithChild(#<h1>Hello</h1>)
For multi-line markup <text> is required as well:
#HelperWithChild(#<text>
#AnotherHelper()
<h1>
With more markup
</h1>
</text>)
#helper AnotherHelper()
{
<p>
Another helper
</p>
}
Though I'm not sure how this will play out with Model - my helpers only use their parameters.

How to generate HTML using ASP.NET MVC helper without the id property? [duplicate]

By default, MVC's input html helpers generate "id" and "name" with the same value. In my case i do not need the id, and when i do, I always enter a custom value. Auto generating unnecessary id's increases the document size, and makes me nerves, because i might be using the same id in my CSS or JavaScript code.
Can i alter the default behavior of the html helpers, so the id is not generated unless manually defined.
I know that i can tell the helpers not to generate an id by passing new { id = "" }, but this approach is not very convenient for large, data-entry-type applications.
Is there an easy way to alter this behavior, or do i need to write custom html helpers?

use,
Html.TextBoxFor(m => m.Text).RemoveNameIdAttribute()
public static MvcHtmlString RemoveNameIdAttribute(this MvcHtmlString helper)
{
if (helper == null)
throw new ArgumentNullException();
var element = helper.ToString();
var regex = new Regex("(id|name)[^'\"]*['\"][^'\"]*['\"]",RegexOptions.IgnoreCase | RegexOptions.Compiled);
return MvcHtmlString.Create(regex.Replace(element, ""));
}

I don't believe you can override the default behavior of the HTML Helpers... but can give some bits of advice.
I'm not worried about extra "id" normally, as proper CSS structure and convention can help to prevent that. Where there can be conflict, send in a new { id = "foo", name = "foo" }.
I seriously doubt that the "id = myfield" characters are going to add up to much. If you're interested in compression, you could take a look at Combres: (http://combres.codeplex.com/).
Outside of this, the solution may be to create your own HTML helpers, which can override the basic ones, passing in your new { id = "" } (Haven't tested that.)
Hope that helps.

Always output raw HTML using MVC3 and Razor

I’ve got a class with a property that looks like this:
[AllowHtml]
[DataType(DataType.MultilineText)]
public string Description { get; set; }
I’ve already put in the [AllowHtml] attribute to let me submit HTML to this property via the form that I’ve built, but what I want to do is output the value of the property as the raw HTML without it being escaped.
I know I can use Html.Raw(Model.Description) but what I’m looking for is some way of telling Html.DisplayFor(m => m.Description) to always output the raw HTML. Is there an attribute I can use to decorate the properties in my class that I wish to behave like that?
Basically it’s me being lazy—I don’t want to have to remember which properties might contain HTML, so I don’t want to have to think about using Html.Raw(…) when I need to do the above—I’d much rather my Model know what it should do and do it automatically. I’ve tried searching for an answer, but either I’m not phrasing it correctly or there’s no way of doing it :(
Thanks,

Change your Description proerpty to return an HtmlString.
Razor does not escape HtmlString values.
(In fact, all Html.Raw does is create an HtmlString)

This is actually rather simple (once you know how...). Change your DataType attrib to [DataType(DataType.Html)], and create a partial view, put it in Views/Shared/DisplayTemplates/Html.cshtml, with this:
#model string
#Html.Raw(Model)
Of course you can also not change your DataType attrib, and name the view MultilineText.cshtml instead of Html.cshtml.

Just to provide a bit more info here - your issue is that # will always HtmlEncode unless you have IHtmlString returned - so the issue is sourced at the # symbol. It's one of the benefits of the razor syntax - its safer to htmlencode than to not. So there is no 'quick' way here since the root of your issue is the # symbol which will exclude HtmlEncoding if it finds IHtmlString. So - no 'quick' way around this unless you use the old <% syntax which IMHO sucks compared to razor : )