RoR: NoMethodError when executing delete_all for a has_many relationship

Question

My classes are as follows, with Customer inheriting from User using the single-table inheritance approach. User has attributes name and email while Order has destination.

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Answer 1

I guess you were right about the problem about the ruby version. I found this question.

The guy had a similar problem and he fixed it by switching his ruby version from ruby-2.2.0 to ruby-2.1.1.

If it's not the ruby version, it could be the ActiveRecord Version.