How to apply joins on different context files

Question

var InsertionId = 
    _DvContext.DvInsertionOrder
        .Select(x => new { x.Id, x.KiteDealId, x.KiteCampaignId, x.CampaignId })
        .ToList();

var camapignId = _kcdbContext.KiteLineitems
                 .Select(x=> new { x.CampaignId, x.Id }).ToList(); 

I have these two queries how I apply join on it. In where condition I want to match campaignID.

Answer 1

You cannot join two dbcontext on one request. You must store them in memory.

By executing ToList(), the EF/SQL query is executed and it is now in memory. So you could try now something like this

//implement your where and select, etc.
var objectsFromContext1 = _dbContext1.Entities.(where,select to DTOObject1).ToList();

//implement your where and select, etc.
var objectsFromContext2 = _dbContext2.Entities.(where,select to DTOObject2).ToList();

var joined = objectsFromContext1.Join(objectsFromContext2 ,
                      db1 => db1.PropertyToBeBasisOfJoined, 
                      db2 => db2.PropertyToBeBasisOfJoined, 
                      (db1 , db2 ) => new MyJoinedClass
                      {
                         //properties
                      }).ToList();