Can i join the list object in .NET collection with the enity object in EF

Question

Can I join the list object in .net collection with the enity object in EF for example

   var prodts = from req in Product
               join prod in context.ProductApplications on req.ProductGUID equals prod.ProductGUID 
              slect req;

Product is the lsit object. and context.ProductApplications is the Enity object.

Can I join them , can any one please let me know how to join themm

Answer 1

You can do that, yes. Alternative method-chaining syntax:

var prodts = Product.
             Join(
                  context.ProductApplications,
                  req => req.ProductGUID,
                  prod => prod.ProductGUID,
                  (req, prod) => req
                 );

This returns IEnumerable<Product>. The Join method takes IEnumerable<> as the first parameter, so what is going to actually happen is the DB will get queried and context.ProductApplications will be fetched and the results will be enumerated. The resulting object will be used for "joining" with your Product collection.

Update

According to your comments, you have some GUIDs in the Product(s?) collection and you want to fetch all the entities from context.ProductApplications that "match" those GUIDs (correct me if I am wrong). If that's the case, you don't really need a join.

var prodts = context.
             ProductApplications.
             Where(pa => Product.
                         Select(p => p.ProductGUID).
                         Contains(pa.ProductGUID)
                  );