根据mvc中的model属性禁用enable dropdownlist

Question

我试图在我的mvc应用程序中基于model属性禁用或启用dropdownlistfor: -

我在做的是: -

@Html.DropDownListFor(m => m.ParentOrganisationID, new SelectList(Model.ParentOrganisations, "ID", "Name", Model.ParentOrganisationID), new { @id = "ddlParentOrganisations", @class = "form-control css-select", @disabled = Model.IsReadOnly ? "disabled" : "false", @style = "width:40%; height:10%;" })

但即使模型属性"model.IsReadOnly"为false,它也会将下拉列表显示为已禁用.

请建议如何处理此问题,而不使用任何JavaScript

提前致谢

Answer 1

在调用DropDownListForhelper方法中不可能包含条件(if/ternary语句),因为你不能传递一行c#代码(带有你的if条件),它需要一个html属性的对象.此外,以下所有标记都将呈现禁用的SELECT.

<select disabled></select>
<select disabled="disabled"></select>
<select disabled="false"></select>
<select disabled="no"></select>
<select disabled="usingJqueryEnablePlugin"></select>
<select disabled="enabled"></select>

您可以使用if条件检查Model属性的值,并有条件地呈现禁用的版本.

@if (!Model.IsReadOnly)
{
    @Html.DropDownListFor(s => s.ParentOrganisationID, 
                               new SelectList(Model.ParentOrganisations, "ID", "Name"))
}
else
{
    @Html.DropDownListFor(s => s.ParentOrganisationID, 
       new SelectList(Model.ParentOrganisations, "ID", "Name"),new {disabled="disabled"})
}

您可以考虑创建一个自定义的html辅助方法来处理if条件检查.

public static class DropDownHelper
{
    public static MvcHtmlString MyDropDownListFor<TModel, TProperty>
                 (this HtmlHelper<TModel> htmlHelper, 
                  Expression<Func<TModel, TProperty>> expression,
                  IEnumerable<SelectListItem> selectItems,
                  object htmlAttributes,
                  bool isDisabled = false)
    {
        ModelMetadata metadata = ModelMetadata.FromLambdaExpression(expression,
                                                                    htmlHelper.ViewData);

        IEnumerable<SelectListItem> items =
            selectItems.Select(value => new SelectListItem
            {
                Text = value.Text,
                Value = value.Value,
                Selected = value.Equals(metadata.Model)
            });
        var attributes = HtmlHelper.AnonymousObjectToHtmlAttributes(htmlAttributes);
        if (isDisabled && !attributes.ContainsKey("disabled"))
        {
             attributes.Add("disabled", "disabled");
        }
        return htmlHelper.DropDownListFor(expression,items, attributes);
    }
}

现在在你的剃刀视图中,调用这个帮助器

@Html.MyDropDownListFor(s=>s.ParentOrganisationID,
               new SelectList(Model.ParentOrganisations, "ID", "Name")
                                           ,new { @class="myClass"},Model.IsReadOnly)