Active Record Grouping in Ruby On Rails

Question

record = #<ActiveRecord::AssociationRelation 
[#<User id: 2, store_id: 3,location: 'xxx'>, 
#<User id: 4, store_id: 3,location:'yyy'>, 
#<User id: 5, store_id: 4,location:'zzz'>, 
#<User id: 6, store_id: 4,location:'aaa'> ]>

How to group location in comma seperated form based on store_id in ruby to get the result as,

The location of store-id(3) should be combained with comma as (yyy,xxx),

then the location of store-id(4) should be combained with comma as (zzz,aaa)

#< store_id: 3,location:'yyy,xxx'>
#< store_id: 4,location:'zzz,aaa'>

How exactly you want to group? By `store_id`, by `location` or both? It isn't clear from your question. — Alexaner Tipugin, Apr 06 '15 at 18:57
Are you actually asking for a `sort` rather than a `group`? It looks like, from the little info you've given, that you want a sort. — Beartech, Apr 06 '15 at 19:27

score 0 · Accepted Answer · edited May 23 '17 at 12:28

Using Enumerable.group_by you can do it this way:

User.all.group_by(&:store_id).map{|store_id,records| {store_id: store_id, location: records.map(&:location).join(',')}}

If you want to do the grouping on database level, using the group method from ActiveRecord, it is required to have a function on the database that takes care of the concatenation, so the solution would depend on the database being used.

For example, in MySQL (see Can I concatenate multiple MySQL rows into one field?)

User.group("store_id").select("store_id, GROUP_CONCAT(location SEPARATOR ',') as location")

Active Record Grouping in Ruby On Rails

1 Answers1