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Conditions on a has_many :through and ActiveRecord 4.1 enum
Say you have a set of models (model names sanitized for generic posting) where the join table in the middle of a has_many :through has an enum that you want to add a filtered association for. class Student < ActiveRecord::Base has_many :student_grades has_many :grades, through: :student_grades end class StudentGrade < ActiveRecord::Base enum approval_status: [:not_reviewed, :rejected,…
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has_many :through, self referential models
Hat tip to [has_many :through self-referential example] that sent me down the correct path on this. The challenge I had went a little deeper than the aforementioned post, however. I’m going to reuse the friend example, but with a twist. class Person < ActiveRecord::Base # id :integer end class Friendship < ActiveRecord::Base # source_friend_id :integer…
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Principle of Least Surprise (Astonishment), foreign keys, and Rails
In yesterday’s post, I sorted through the foreigner gem to figure out how to change the reference column (primary key) that a foreign_key maps to. The problem here is that, unless your Rails project(s) has grown up referencing “natural” primary keys instead of the autoincremented id implicit in an ActiveRecord::Migration, avoiding creating surprise by not…