Generic method to get property values with Linq Expression and reflection

Question

Dear Gods of Reflection

I would like to have a generic GetValue method that can return the following property values given the following

Answer 1

The problem is here:

if (response != null)
{
   var expr = (MemberExpression)propertyExpression.Body;
   var prop = (PropertyInfo)expr.Member;
   return (T)prop.GetValue(response);
}

This only works if your expression references a property directly, otherwise propertyExpression.Body will not be a MemberExpression and you'll get a run-time cast error. The three that don't work do not reference a property directly - the first two reverence a method on top of a property (the indexer) and the last references a nested property.

Since all you want is the value of the expression, though, I think you can just do:

if (response != null)
{
   Func<TEntity, T> func = propertyExpression.Compile();  
   return func(response);
}

If you intended to do other things with the expression (like get the name of the property), then you'll need to decide if you want to support expressions that don't reference a property directly and add handlers for that.

Answer 2

You can do it simply by Executing your Lambda expression:

        if (response != null)
        {
            return propertyExpression.Compile().Invoke(response);
        }