Get unique ids from 2 has_many relationships in rails

Asked Feb 19 '13 at 11:31

Active Feb 19 '13 at 11:31

Viewed 350 times

I can't find a simple way to get the ids of pointfields from this relationship

pointtype has_and_belongs_to_many pointfields 
pointfield has_and_belongs_to_many pointtypes

I do the following :

@pointtypes = current_project.points.map{|p| p.pointtype}.uniq
@pointtypes = @pointtypes - [nil]                      # tricky... Is this Railsy ?
@pointfield_ids = @pointtypes.map(&:pointfield_ids)

returns

 [[16, 17, 18, 23, 24, 25, 26, 27, 28, 29], [16, 17, 32, 33, 34, 35, 36]]

and thus

@pointfield_ids.uniq!

is not working because there is two sub-arrays...

What I need is to get one single array with the unique ids of the pointfields (or the objects itself)

asked Feb 19 '13 at 11:31

Stéphane V

1,094
2
11
25

3

use pointfield_ids.flatten.uniq! – jvnill Feb 19 '13 at 11:32
1

also you can use @pointtypes.compact! to remove nil elements – jvnill Feb 19 '13 at 11:33
@pointfields.flatten!.uniq! did the trick :-) (I added a "!" after "flatten") – Stéphane V Feb 19 '13 at 12:47
ah right. i was thinking that calling .uniq! at the end, it would affect the object but since flatten returns a new record, it wont. – jvnill Feb 19 '13 at 12:50

Get unique ids from 2 has_many relationships in rails

0 Answers0