One very useful method provided by Rails is first_or_create

But there’s a substantial probability that one might use it like this:

Model.first_or_create(x: 1, y: 2)

At least I did at first. It caused a bug in that nothing ever gets created with {x=1, y=2}. This is because Model.first already returns an object - where(id=1) - so the create part doesn’t get called.

The desired behaviour would be achieved by:

Model.where(x: 1, y: 2).first_or_create