Linq many to many?

Question

Say I have products and receipts in a many to many relation. Is there any way I can directly query product.receipts or receipt.products and get the Iqueryable without having to reference the join_table at all?

Linq to SQL or Linq to Entities or Linq to NHibernate or ... ? — Rob Fonseca-Ensor, Feb 01 '10 at 12:47
@IainGalloway Just because your answer is C#, doesn't mean the question was C#. Was that really worth the edit? — Rawling, May 06 '15 at 11:06

score 2 · Accepted Answer · edited May 23 '17 at 12:19

I assume you're using Linq-to-SQL.

The answer is "no, but..."

You can work with many-many relationships in Linq-to-SQL, but you do need to have a separate type representing the junction table.

If you just want to e.g. databind against a child property of a model object you can do something really simple like:-

public partial class Order
{
  public IEnumerable<Product> Products
  {
    get { return Order_Details.Select(x => x.Product); }
  }
}

Beware of the select-n-plus-one problem though if you then want to use that any time you're using a list of Orders.

More info: http://www.iaingalloway.com/2015/06/many-to-many-relationships-in-linq-to-sql.html and here.

Also, there's a whole bunch of duplicate questions:-

LINQ many-to-many relationships: Solution?

How to load Many to many LINQ query?

and tons more.

This is the main reason why I moved from L2S to Entity Framework, and then hit a whole bunch of different issues ;) — Zhaph - Ben Duguid, Feb 01 '10 at 16:38

score 0 · Answer 2 · answered Feb 01 '10 at 12:50

0

Linq to Entities and the Entity Framework supports many to many relations. I know Linq to Sql does not, and I think (not sure) Linq to NHibernate does support many to many. (I know NHibernate supports many-to-many)

answered Feb 01 '10 at 12:50

Dan McClain

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Linq many to many?

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