Combine two ActiveRecord::Relation objects

ruby-on-rails rails-activerecord arel
Patrick Klingemann picture Patrick Klingemann · Mar 2, 2012 · Viewed 105.7k times · Source

Suppose I have the following two objects:

first_name_relation = User.where(:first_name => 'Tobias') # ActiveRecord::Relation
last_name_relation  = User.where(:last_name  => 'Fünke') # ActiveRecord::Relation

is it possible to combine the two relations to produce one ActiveRecord::Relation object containing both conditions?

Note: I'm aware that I can chain the wheres to get this behavior, what I'm really interested in is the case where I have two separate ActiveRecord::Relation objects.

Answer

Andrew Marshall picture Andrew Marshall · Mar 2, 2012

If you want to combine using AND (intersection), use merge:

first_name_relation.merge(last_name_relation)

If you want to combine using OR (union), use or†:

first_name_relation.or(last_name_relation)

† Only in ActiveRecord 5+; for 4.2 install the where-or backport.

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