LINQ to Entities many to many relationship?

It's rarely correct to use join in L2E/L2S Use associations/navigation properties instead Off the top of my head (may require some tweaking): var QueryResults = from project in ProjectSet let p = project.Contacts. FirstOrDefault(c => c. IsPrimary) let s = project.Contacts.

FirstOrDefault(c => c. IsSecondary) group project by new { Primary = p, Secondary = s } into g select new EmailDetails { PrimaryContact = g.Key. Primary, SecondaryContact = g.Key.

Secondary, Projects = from proj in g select new ProjectDetails { Project = proj, Region = proj. Region, ProjectItems = proj. ProjectItems } }.

It's rarely correct to use join in L2E/L2S. Use associations/navigation properties instead. Off the top of my head (may require some tweaking): var QueryResults = from project in ProjectSet let p = project.Contacts.

FirstOrDefault(c => c. IsPrimary) let s = project.Contacts. FirstOrDefault(c => c.

IsSecondary) group project by new { Primary = p, Secondary = s } into g select new EmailDetails { PrimaryContact = g.Key. Primary, SecondaryContact = g.Key. Secondary, Projects = from proj in g select new ProjectDetails { Project = proj, Region = proj.

Region, ProjectItems = proj. ProjectItems } }.

Thanks. This has got me much closer to what I need. Primary and secondary contacts, and projects have some associated entities I need access to.

A contact has a navigation property to an Organisation object and a navigation property for a list of phone numbers. A project has a reference to a Region object and a list of ProjectItems. How can I efficiently get this data into memory?

I'm usng EF3.5 so I believe lazy loading isn't an option? Sorry if I'm a bit off with the terminology, I'm still learning the ins and outs of this framework. – Luke CK Sep 15 '10 at 13:12 Easy way to do this in 3.5 (and 4) is to change EmailDetails.

Projects to IEnumerable (i.e. , a view or edit model, not an entity) and project onto that. I'll update the example.

– Craig Stuntz Sep 15 '10 at 13:33 Thanks. That works but is there a way to do this that doesn't require the creation of ProjectDetails and ContactDetails classes? I'd like to be able to access the region and ProjectItems via the navigation properties.It feels like it shouldn't be necessary to create new data structures just to be able to access related objects.

– Luke CK Sep 15 '10 at 14:03 What makes you think you can't access these properties? Did you try what I suggested? Anonymous types work just as well if you don't like creating POCOs.

– Craig Stuntz Sep 15 '10 at 14:13.

It's rarely correct to use join in L2E/L2S . Use associations/navigation properties instead.

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