How can I add a class attribute to an HTML element

问题:

ASP.NET MVC can generate HTML elements using HTML Helpers, for example @Html.ActionLink(), @Html.BeginForm() and so on.

I know I can specify form attributes by creating an anonymous object and pass that object for the (fourth in this case) htmlAttributes parameter where specifying an id for the element:

Html.BeginForm("Foo", "Bar", FormMethod.Post, new { id = "MyForm"})

But what about the class attribute? Obviously this does not work:

Html.BeginForm("Foo", "Bar", FormMethod.Post, new { class = "myclass"})

As that just throws random syntax errors when my view is requested, because it expects something else after encountering the C# keyword class.

I've also tried:

new { _class = "myclass"}

and

new { class_ = "myclass"}

But they also did not work, as the underscores get replaced by dashes.

I know that I can just as well write the HTML elements by hand or wrap the form inside a <div class="myClass">, but I'd still be interested to know how it is supposed to be done.

回答1:

In order to create an anonymous type (or any type) with a property that has a reserved keyword as its name in C#, you can prepend the property name with an at sign, @:

Html.BeginForm("Foo", "Bar", FormMethod.Post, new { @class = "myclass"})

For VB.NET this syntax would be accomplished using the dot, ., which in that language is default syntax for all anonymous types:

Html.BeginForm("Foo", "Bar", FormMethod.Post, new with { .class = "myclass" })

回答2:

Current best practice in CSS development is to create more general selectors with modifiers that can be applied as widely as possible throughout the web site. I would try to avoid defining separate styles for individual page elements.

If the purpose of the CSS class on the <form/> element is to control the style of elements within the form, you could add the class attribute the existing <fieldset/> element which encapsulates any form by default in web pages generated by ASP.NET MVC. A CSS class on the form is rarely necessary.