Is there a way to get entity id-field's name by reflection or whatever?

Question

Hi

I am trying to get the ID field name (property name) of an entity, is it possible?

User user= new User(); //User is an Entity

string idField = ??????? //user.UserId

Answer 1

Entity class is still a class which inherits from System.Data.Objects.DataClasses.EntityObject, so, i think reflection will still work on it.

Have you tried it? Do you get any error?

Answer 2

This post in the Entity Framework support forums shows how to use reflection to find ID fields and their details.

Answer 3

public static IEnumerable<string> GetIdFields<TEntity>() where TEntity : EntityObject
{
    var ids = from p in typeof(TEntity).GetProperties()
              where (from a in p.GetCustomAttributes(false)
                     where a is EdmScalarPropertyAttribute &&
                     ((EdmScalarPropertyAttribute)a).EntityKeyProperty
                     select true).FirstOrDefault()
              select p.Name;
    return ids;
}

public static string GetIdField<TEntity>() where TEntity : EntityObject
{
    IEnumerable<string> ids = GetIdFields<TEntity>();
    string id = ids.Where(s => s.Trim().StartsWith(typeof(TEntity).Name.Trim())).FirstOrDefault();
    if (string.IsNullOrEmpty(id)) id = ids.First();
    return id;
}

You could merge both funcs into one or set your search conditions.