Question

I have one class called Requestparent.
I have 3 classes called requesttype1, requesttype2, requesttype3, all 3 inherit from RequestParent.

In one of the screens I need to make a query to show all opened requests of all types in a grid

something like:
Opened Date – Type – Opened by.

If I query the requestparent, I wont get the type.

Another solution would be to make 3 different queries to the child objects.

EF created a discriminator column automatically.

Answer 1

If you make a select query to a base type; then if creates join statements to the child tables and creates entities of child types.

Thus, even if you make a query to the base table, it creates entities of child types. You can just use Entity.GetType() statement to get the type of the entity.

For example, let’s say you have a base entity called Base and two derived entities called Derived1 and Derived2. Then if you run the following select statement;

List<Base> temp = (from o in context.Base
           select o).ToList<Base>();

You will have entities of type Derived 1 and Derived 2. Just employing oftype is enough to determine the type of the entity. For example;

if (temp[0].GetType() == typeof(X))
   {
          .... 
   }