Dynamically set the disabled html attribute for Te

问题:

I'm trying to dynamically set the disabled attribute for the TextBoxFor HtmlHelper

@Html.TextBoxFor(model => model.Street, 
                 new
                 {
                    @class = "", 
                    disabled = (Model.StageID==(int)MyEnum.Sth) ? "disabled" : "" 
                 })

but even if there is disabled="" it is the same as disabled="disabled". How to get around of this ?

回答1:

I have the same problem about month ago and I finished by using this extension method for it

public static class AttributesExtensions
{
    public static RouteValueDictionary DisabledIf(
        this object htmlAttributes, 
        bool disabled
    )
    {
        var attributes = new RouteValueDictionary(htmlAttributes);
        if (disabled)
        {
            attributes["disabled"] = "disabled";
        }
        return attributes;
    }
}

And after that you can use it like this

@Html.TextBoxFor(
    model => model.Street, 
    new { @class = "" }.DisabledIf(Model.StageID==(int)MyEnum.Sth)
)

EDIT (after Paul's comment):

The using of data-xxx html attributes may be mined by using the constructor of the System.Web.Routing.RouteValueDictionary class, since underscores will not be automatically converted to minus sign.

Use the method System.Web.Mvc.HtmlHelper.AnonymousObjectToHtmlAttributes instead: will solve this issue.

UPDATED CODE (Extension method body only)

var attributes = HtmlHelper.AnonymousObjectToHtmlAttributes(htmlAttributes);
if (disabled)
{
    attributes["disabled"] = "disabled";
}
return attributes;

回答2:

Using the extension method below produces similar results, but this is perhaps more fragile:

@Html.TextBoxFor(
     model => model.Street, 
     new { @class = "form-control" }
).DisabledIf(Model.IsReadOnly)

Extension:

using System.Text.RegularExpressions;
using System.Web.Mvc;

namespace xxx.HtmlHelpers
{
    public static class MvcHtmlStringExtensions
    {

        private static readonly Regex OpeningTagPattern;

        static MvcHtmlStringExtensions()
        {
            OpeningTagPattern = new Regex("<[a-zA-Z]*");
        }

        public static MvcHtmlString DisabledIf(this MvcHtmlString controlHtml, bool isDisabled)
        {
            if (!isDisabled) return controlHtml;
            return
                new MvcHtmlString(OpeningTagPattern.Replace(controlHtml.ToString(),
                    x => string.Format("{0} disabled=\"disabled\"", x.Groups[0])));
        }

    }
}

回答3:

Probably your stage Id is not getting set

@{ 
    if(Model.StageID != null &&   Model.StageID > 0)
    {
        @Html.TextBoxFor(model => model.Street, 
             new
             {
                @class = "", 
                disabled = (Model.StageID==(int)MyEnum.Sth) ? "disabled" : "" 
             })
    }else{

        @Html.TextBoxFor(model => model.Street, 
             new
             {
                @class = ""
             })
    }
}

回答4:

We actually just ran into the same problem. We ended up implementing an extension method with overloaded parameters, which takes in a boolean indicating whether or not we want the control disabled. We just add the "disabled" attribute when appropriate, and let the built-in HtmlHelper handle the heavy lifting.

Extension class and method:

using System;
using System.Collections.Generic;
using System.Linq.Expressions;
using System.Web.Mvc;
using System.Web.Mvc.Html;
using System.Web.Routing;
public static class OurHtmlHelpers
{
    public const string DisabledAttribute = "disabled";

    public static MvcHtmlString TextBoxFor<TModel, TProp>(this HtmlHelper<TModel> htmlHelper, 
                                                            Expression<Func<TModel, TProp>> expression, 
                                                            object htmlAttributes, 
                                                            bool canEdit)
    {
        var htmlAttributeDictionary = SetDisabledAttribute(htmlAttributes, canEdit);

        return htmlHelper.TextBoxFor(expression, htmlAttributeDictionary);
    }        

    private static RouteValueDictionary SetDisabledAttribute(object htmlAttributes, bool canEdit)
    {
        var htmlAttributeDictionary = new RouteValueDictionary(htmlAttributes);

        if (!canEdit)
        {
            htmlAttributeDictionary.Add(DisabledAttribute, DisabledAttribute);
        }

        return htmlAttributeDictionary;
    }
}

Then you just need to reference your new class and call @Html.TextBoxFor(m => m.SomeValue, new { @class = "someClass" }, <Your bool value>)

It's worth noting that you'd have to define these extensions for any of the TextBoxFor overloads you'd like to use, but it seems like a reasonable trade off. You can also utilize most of the same code for other HtmlHelpers you'd like to add the functionality to.