c# - 修改 ASP.NET MVC 2 中的 HTML Helpers

Question

我想修改像这样的助手:

<%= Html.CheckBoxFor(m => m.Current, new { @class = "economicTextBox", propertyName = "Current", onchange = "UseCurrent();UpdateField(this);" })%>

还将另一个表示应用程序权限的字符串作为参数，然后在方法内部我将根据他们的权限确定是否返回实际的 HTML 或什么都不返回。

我该怎么做？

更新 2:复选框未呈现为只读

当我调试并检查 htmlHelper.CheckBoxFor(expression, mergedHtmlAttributes)._value 的值时，我得到了这个

<input checked="checked" class="economicTextBox" id="Current" name="Current" onchange="UseCurrent();UpdateField(this);" propertyName="Current" readonly="true" type="checkbox" value="true" /><input name="Current" type="hidden" value="false" />

但复选框仍在呈现，允许我更改它并实现全部功能。为什么？

Answer 1

您可以编写一个自定义助手:

public static MvcHtmlString MyCheckBoxFor<TModel>(
    this HtmlHelper<TModel> htmlHelper,
    Expression<Func<TModel, bool>> expression, 
    string permission, 
    object htmlAttributes
)
{
    if (permission == "foo bar")
    {
        // the user has the foo bar permission => render the checkbox
        return htmlHelper.CheckBoxFor(expression, htmlAttributes);
    }
    // the user has no permission => render empty string
    return MvcHtmlString.Empty;
}

然后:

<%= Html.CheckBoxFor(
    m => m.Current, 
    "some permission string",
    new {  
        @class = "economicTextBox", 
        propertyName = "Current", 
        onchange = "UseCurrent();UpdateField(this);" 
    }) 
%>

---

更新:

以下是如何修改 HTML 帮助程序，以便在用户没有权限时呈现只读复选框而不是空字符串:

public static MvcHtmlString MyCheckBoxFor<TModel>(
    this HtmlHelper<TModel> htmlHelper,
    Expression<Func<TModel, bool>> expression,
    string permission,
    object htmlAttributes
)
{
    if (permission == "foo bar")
    {
        // the user has the foo bar permission => render the checkbox
        return htmlHelper.CheckBoxFor(expression, htmlAttributes);
    }
    // the user has no permission => render a readonly checkbox
    var mergedHtmlAttributes = new RouteValueDictionary(htmlAttributes);
    mergedHtmlAttributes["readonly"] = "readonly";
    return htmlHelper.CheckBoxFor(expression, mergedHtmlAttributes);
}