Question

The error message I am getting is:

The type arguments for method ‘System.Linq.Queryable.Contains(System.Linq.IQueryable, TSource)’ cannot be inferred from the usage. Try specifying the type arguments explicitly.

When I run the following code I get an error message saying that I need to explicitly specify the type of argument for method contains.

var result2 = from cltIntake in db.Client_Intakes
              where (from cltElig in db.Client_Eligibility_Referrals
                     where (
                            from cltDoctVerif in db.Doct_Verifications
                            where cltDoctVerif.Verification_Status == "Yes"
                            select cltElig.Asgnd_Caseworker_ID == 6
                            ).Contains(cltElig.Client_Eligibility_ID)
                     select new { client_Eligibility_ID = cltElig.Client_Eligibility_ID }
                    ).Contains(cltIntake.Client_Intake_ID)
                select new
                  {
                      cltInfo.First_Name,
                      cltInfo.Last_Name,

                  };

I have looked around a lot and tried to cast to type int, since the collection is type int, as follows

.Contains<Int32>(cltElig.Client_Eligibility_ID)

but that threw an error saying:

Instance argument: cannot convert from ‘System.Linq.IQueryable’ to ‘System.Linq.IQueryable’
Instance argument: cannot convert from ‘System.Linq.IQueryable’ to ‘System.Linq.IQueryable’

I really appreciate if someone gives me a solution for this. The thing is I don’t really know much about IQueryable.
Thank you

Answer 1

The problem is that your selection is creating a sequence of anonymous types, but your call to Contains is passed a Int

So rather than select new { client_Eligibility_ID = cltElig.Client_Eligibility_ID } just do select cltElig.Client_Eligibility_ID additionally you have select cltElig.Asgnd_Caseworker_ID == 6' which is projecting a boolean. You probably wanted&& cltElig.Asgnd_Caseworker_ID == 6`

Additionally, consider simplifying the query

var result2 = from cltIntake in db.Client_Intakes
              from cltElig in db.Client_Eligibility_Referrals
              from cltDoctVerif in db.Doct_Verifications
              where cltDoctVerif.Verification_Status == "Yes"
                   && cltElig.Asgnd_Caseworker_ID == 6
                   && cltDoctVerif.Client_Eligibility_ID == 
                          cltElig.Client_Eligibility_ID
                   && cltElig.Client_Eligibility_ID == 
                          cltIntake.Client_Intake_ID
            select new
              {
                  cltInfo.First_Name,
                  cltInfo.Last_Name,
              };