Rails find_or_create_by more than one attribute?

Multiple attributes can be connected with an and:

GroupMember.find_or_create_by_member_id_and_group_id(4, 7)

(use find_or_initialize_by if you don't want to save the record right away)

Edit: The above method is deprecated in Rails 4. The new way to do it will be:

GroupMember.where(:member_id => 4, :group_id => 7).first_or_create

and

GroupMember.where(:member_id => 4, :group_id => 7).first_or_initialize

Edit 2: Not all of these were factored out of rails just the attribute specific ones.

https://github.com/rails/rails/blob/4-2-stable/guides/source/active_record_querying.md

Example

GroupMember.find_or_create_by_member_id_and_group_id(4, 7)

became

GroupMember.find_or_create_by(member_id: 4, group_id: 7)

For anyone else who stumbles across this thread but needs to find or create an object with attributes that might change depending on the circumstances, add the following method to your model:

# Return the first object which matches the attributes hash# - or -# Create new object with the given attributes#def self.find_or_create(attributes)  Model.where(attributes).first || Model.create(attributes)end

Optimization tip: regardless of which solution you choose, consider adding indexes for the attributes you are querying most frequently.

In Rails 4 you could do:

GroupMember.find_or_create_by(member_id: 4, group_id: 7)

And use where is different:

GroupMember.where(member_id: 4, group_id: 7).first_or_create

This will call create on GroupMember.where(member_id: 4, group_id: 7):

GroupMember.where(member_id: 4, group_id: 7).create

On the contrary, the find_or_create_by(member_id: 4, group_id: 7) will call create on GroupMember:

GroupMember.create(member_id: 4, group_id: 7)

Please see this relevant commit on rails/rails.