Cannot eagerly load the polymorphic association

Question

I get the error Cannot eagerly load the polymorphic association :messageable_fromuser

online = Message.all.joins(:messageable_fromuser)

I tried

online = Message.all.includes(:messageable_fromuser)

But it doesn't include the joined table in the result. I see two queries in my log when using includes. I don't know why people recommend using includes to eager load. How is two queries going to join anything?

Answer 1

Using preload should solve the error:

online = Message.preload(:messageable_fromuser)