How to aggregate query results from multiple collections in MongoDB?

Asked Oct 05 '18 at 15:11

Active Oct 07 '18 at 07:22

Viewed 1,426 times

I have a springboot project which has mongoDB as the database. I have multiple collections in my MongoDB. Each category has its own collection similar to following.

Category_A
{ _id: 101, firstName: "Emma", surname: "Jackson", city: "Manchester"}
{ _id: 102, firstName: "Jane", surname: "Reynolds", city: "York"}

Category_B
{ _id: 201, firstName: "Julia", surname: "Jacob", city: "York"}
{ _id: 202, firstName: "Eric", surname: "Philips", city: "Bristol"}

Category_C
{ _id: 301, firstName: "Annie", surname: "Jones", city: "York"}
{ _id: 302, firstName: "Ryan", surname: "Lewis", city: "Bristol"}

I have to query all the collections to find the people from York and put them in a view to perform limit and skip on the view to support pagination.

I am not sure how to perform the union of query results from each collection into a single view. Is limit and skip applicable for view?

edited Oct 07 '18 at 07:22

asked Oct 05 '18 at 15:11

BlueStar

Really good question !! See if this helps: https://stackoverflow.com/questions/6502541/mongodb-query-multiple-collections-at-once – Rishabh Agarwal Oct 07 '18 at 10:31
See this also: http://tebros.com/2011/07/using-mongodb-mapreduce-to-join-2-collections/ – Rishabh Agarwal Oct 07 '18 at 10:38
@rishabhagarwal Had a look at those links. They are more of joins than a union. – BlueStar Oct 10 '18 at 02:45
this might help https://docs.mongodb.com/manual/reference/operator/aggregation/group/ – user3807691 Nov 06 '18 at 09:40

How to aggregate query results from multiple collections in MongoDB?

0 Answers0