ASP.NET MVC。 如何使用DisplayNameFor来创建表标题和正文？

Question

How get a property display name using DisplayNameFor() to build a table header. for instance:

   @model IEnumerable<Item>
   <table class="table">
        <thead>
            <tr>
                <td>@Html.DisplayNameFor(? => ?.prop1)</td>
                <td>@Html.DisplayNameFor(? => ?.prop2)</td>
                <td>@Html.DisplayNameFor(? => ?.prop3)</td>
            </tr>
        </thead>
        <tbody>
            @foreach (Item item in Model) {
                <tr>
                    <td>@Html.DisplayFor(i => item.prop1)</td>
                    <td>@Html.DisplayFor(i => item.prop2)</td>
                    <td>@Html.DisplayFor(i => item.prop3)</td>
                </tr>
            }    
        </tbody>
    </table>

what should I write in the question marks?

Answer 1

DisplayNameFor() has an overload that accepts IEnumerable<T> so it simply needs to be

<td>@Html.DisplayNameFor(m => m.prop1)</td>

Note that this only works where the the model is Enumerable<T> (in you case @model IEnumerable<Item> ).

But will not work if the model was an object containing a proeprty which was IEnumerable<T> .

For example, the following will not work

<td>@Html.DisplayNameFor(m => m.MyCollection.prop1)</td>

and it would need to be

<td>@Html.DisplayNameFor(m => m.MyCollection.FirstOrDefault().prop1)</td>

which will work even if the collection contains no items.

Side note: Under some circumstances, you may initially get a razor error, but you can ignore it. Once you run the app, that error will disappear.

Answer 2

You could do like this:

   @model IEnumerable<Item>
   <table class="table">
        <thead>
            <tr>
                <th>@Html.DisplayNameFor(i => i.First().prop1)</th>
                <th>@Html.DisplayNameFor(i => i.First().prop2)</th>
                <th>@Html.DisplayNameFor(i => i.First().prop3)</th>
            </tr>
        </thead>
        <tbody>
            @foreach (Item item in Model) {
                <tr>
                    <td>@Html.DisplayFor(i => item.prop1)</td>
                    <td>@Html.DisplayFor(i => item.prop2)</td>
                    <td>@Html.DisplayFor(i => item.prop3)</td>
                </tr>
            }    
        </tbody>
    </table>

It may look like you are actually getting the first item of the IEnumerable, but you are not.

Since the parameter you are passing to DisplayFor() is just an Expression Tree, it won't execute IEnumerable's First() method at all, internally DisplayFor() will only check for the passed type (the parameter's type) to use reflection and build a display for it.

Answer 3

If you change the model to an IList<Item> or Item[] you can do this:

   @model IList<Item>
   <table class="table">
        <thead>
            <tr>
                <td>@Html.DisplayNameFor(x => x[0].prop1)</td>
                <td>@Html.DisplayNameFor(x => x[0].prop2)</td>
                <td>@Html.DisplayNameFor(x => x[0].prop3)</td>
            </tr>
        </thead>
        ...
    </table>