Question

I am trying to make a label for a dynamic property using an html helper from the razor engine. The view model is not strongly typed. My knowledge of lambda expressions is not very strong and I am unsure how to produce a dynamic expression that will fit this situation.

public class someModel<TEntity> where TEntity : class
{
    public TEntity Entity { get; set; }
}    

—-

@model dynamic
@{
 string property = "FirstName";
}

@Html.LabelFor( m => m.Entity.property )

Which throws the error An expression tree may not contain a dynamic operation.

I looked into making dynamic expression trees but was unsure if that was overkill or necessary. How can I access properties of the Entity by using strings?

Entity could be a number of different types of classes. Those classes have fully defined data annotations such as [Display(Name = "Some Name")] and the reason I am trying to use LabelFor is to have access to those data annotations.

Answer 1

This is impossible. You cannot use lambda expressions nor strongly typed helpers with dynamic values. You will have to use the weakly typed versions of those helpers:

@model dynamic
@{
    string property = "FirstName";
}

@Html.Label("property")

Yes, once you stop using strongly typed view models, lots of things and habits will have to change.