Using reflection to obtain select fields in a linq query

Question

I am using Linq for my queries and would like to be able to get a list of properties I want returned in the "select" portion using reflection. I've tried the following to no avail:

string[] paramList = new[]{"AppId","Name"};
var query =
                from entity in
                    _ctx.App
                select new {entity.GetType().GetProperties().Where(prop=>paramList.Contains(prop.Name) )};

What am I missing here?

Answer 1

When working with reflection inside a EF query you would need to write the expression yourself. Look at these existing question for more information

• Help with Linq and Generics. Using GetValue inside a Query
• How to reflect over T to build an expression tree for a query?
• IQueryable<> dynamic ordering/filtering with GetValue fails

The problem is not Linq itself, but because your query is parsed into an Expression Tree which Entity Framework doesn't understand.