Question

I found this Related Topic, but it failed to answer my question.

When automatically creating a strongly typed view, lets say with a List scaffolding template, I will get something roughly like this:

@model IEnumerable<Test.Models.abc>
<table>
    <tr>
    <th>
        @Html.DisplayNameFor(model => model.ID)
    </th>
</tr>

@foreach (var item in Model) {
<tr>
    <td>
        @Html.DisplayFor(modelItem => item.ID)
    </td>
</tr>
}
</table>

I understand @Html.DisplayNameFor(model => model.ID) completely, but not @Html.DisplayFor(modelItem => item.ID).

What is the purpose of modelItem? Replacing it with any arbitrary text will result in a functional web page. It seems that modelItem is just a throwaway word. I guess my real question is why doesn’t this work?

@Html.DisplayFor(item => item.ID)

Edit

A good point was brought up in the comments. It seems you are also able to change model to anything so long as you change it on both sides of the lambda expression:

@Html.DisplayNameFor(abc => abc.ID)

A side question would be: How does the @model statement at the top affect the functions below? I had previously thought model referenced the @model expression in order to figure out the display name via the class, but the page still works after the mentioned changes.

Answer 1

It does not work because item is already declared in outer scope in foreach.

@foreach (var item in Model).

The reason why modelItem lambda is not used is because of that iteration of IEnumerable. If there would be Test.Models.abc as model instead of IEnumerable, then would that lambda does matter and the code of DisplayFor would change to @Html.DisplayFor(m => m.ItemId).

Update

@model IEnumerable<Test.Models.abc> just declares that this view is strongly typed, with type of IEnumerable<Test.Models.abc> – in your case. That means that view property this.Model (not model) is of type IEnumerable<Test.Models.abc> – and also that model of that type should passed into this view. model in example above is just expression variable – it has scope just for that expression. You can change it’s name to any unprotected legal variable name that was not already used in outer scope (that’s why it should not be named Model, because it would hide the Model property already declared in view).