ASP.Net MVC中的Linq和DisplayFor

Question

I've got a model that has an ICollection of telephone numbers. In my view I want to display the value for the record that is marked as Primary.

@Html.DisplayFor(model => model.Telephones.Where(a=>a.Primary==true).Number)

The .Number is not allowed in the Linq syntax. How would one go about making the above line work or rather what is the proper way to display the number?

I probably should do the logic in the controller and put the value in a view model but it seems like this should be doable.

Answer 1

The Where extension method returns an IEnumerable<T> . If you just want the first item which satisfies the condition, use First :

@Html.DisplayFor(model => model.Telephones.First(a => a.Primary).Number)

If you also need to ensure that exactly one item in the set satisfies the condition (and throw an exception otherwise), consider using Single :

@Html.DisplayFor(model => model.Telephones.Single(a => a.Primary).Number)