CODEWITHSUNDEEP
c#linqentity-frameworkjoin
Luca Romagnoli
Luca Romagnoli

Reputation: 12475

error with linq join

I have this linq query:

var segreterie = from s in db.USR_Utenti join h in db.USR_Accounts
                     on new {s.ID, settings.GruppoSegreteria} 
                     equals new {h.USR_UtentiReference,h.ID_Gruppo} select s;

that has this problem:

The type of one of the expressions in the join clause is incorrect.  Type inference failed in the call to 'Join'.

how can i do to solve it?

Upvotes: 1

Views: 358

Answers (2)

fjxx
fjxx

Reputation: 945

On a similar note, if you are doing a join on a field which is nullable (for e.g., int and int?) you may have to do something like (where Field2 is int? in Table1 and int in Table2):

from l in Table1
join l2 in Table2
  on new { l.Field1, Field2 = (l.Field2.Value == null ? -1 : l.Field2.Value) } equals new { l2.Field1, Field2 = l2.Field2 }

Upvotes: 0

Jon Skeet
Jon Skeet

Reputation: 1503669

The two types should be the same - which means they'll need the same property names as you're using anonymous types. Try this:

var segreterie = from s in db.USR_Utenti join h in db.USR_Accounts
                 on new {s.ID, Groups = settings.GruppoSegreteria} 
                 equals new {ID = h.USR_UtentiReference, Groups = h.ID_Gruppo}
                 select s;

That's assuming that s.ID and h.USR_UtentiReference have the same type, and settings.GruppoSegreteria and h.ID_Gruppo do likewise.

Upvotes: 6

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