LINQ Join Errors - linq

Question

I'm getting the following error:
The type of one of the expressions in the join clause is incorrect. Type inference failed in the call to 'Join'.
when using the code below
var ccrCodes = (from c in db.CCRCodes
join i in items on
new { c.baan_cat_fam_code, c.baan_cat_code } equals
new { i.baan_cat_family_code, i.baan_cat_code }
where i => i.contact_dt.Value.Year == date.Year && i.contact_dt.Value.Month == date.Month
select c).Distinct().OrderBy(c => c.code_desc);
What I'm trying to do in LINQ is create a multi-condition join and am running into problems. Any ideas?
Thanks,

Answer 1

Try giving names to the properties in your anonymous objects:
var ccrCodes = (from c in db.CCRCodes
join i in items on
new { FamCode = c.baan_cat_fam_code, CatCode = c.baan_cat_code } equals
new { FamCode = i.baan_cat_family_code, CatCode = i.baan_cat_code }
where i => i.contact_dt.Value.Year == date.Year && i.contact_dt.Value.Month == date.Month
select c).Distinct().OrderBy(c => c.code_desc);
EDIT: Alright, I have to confess, I am no expert on query syntax, but you want to filter the 'items' list before doing the join, like the following fluent version of your query:
db.CCRCodes
.Join(
items.Where(i => i.contact_dt.Value.Year == date.Year && i.contact_dt.Value.Month == date.Month),
x => new { FamCode = x.baan_cat_fam_code, CatCode = x.baan_cat_code },
x => new { FamCode = x.baan_cat_family_code, CatCode = x.baan_cat_code },
(o,i) => o
).Distinct().OrderBy(c => c.code_desc)
ANOTHER EDIT: Per Ahmad's suggestion:
var ccrCodes = (from c in db.CCRCodes
join i in items.Where(x => x.contact_dt.Value.Year == date.Year && x.contact_dt.Value.Month == date.Month) on
new { FamCode = c.baan_cat_fam_code, CatCode = c.baan_cat_code } equals
new { FamCode = i.baan_cat_family_code, CatCode = i.baan_cat_code }
select c).Distinct().OrderBy(c => c.code_desc);
YET ANOTHER EDIT: Per another Ahmad suggestion:
var ccrCodes = (from c in db.CCRCodes
from i in items
where i.contact_dt.Value.Year == date.Year && i.contact_dt.Value.Month == date.Month
&& c.baan_cat_fam_code == i.baan_cat_family_code && c.baan_cat_code == i.baan_cat_code
select c).Distinct().OrderBy(c => c.code_desc);