Entity Framework groupby children collection

Question

I use Entity Framework 6, I have such database structure (simplified):

Transactions - Id - DateTime - ...

Products - Id - Name

TransactionsItems - Id - TransactionId - ProductId

As you see relation Transaction <-> Product is many to many type.

I don't know how to group transactions by products using LINq - something like

transactions.GroupBy(t => t.TransactionsItems.Product)

where TransactionsItems property is navigation property generated by entity framework and contains collection of items related to this transaction.

I know I can iterate all products and then search for transactionItems and accumulate data, but I wonder whether is there any simplier method to achieve my goal?

Answer 1

Maybe you just got to group by a specific column :

transactions.GroupBy(t => t.TransactionsItems.Product.Name)