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Augusts Bautra
Augusts Bautra

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How to split out a specific case from a polymorphic association

#rails #polymorphic

Let's say we have a model structure that allows us to make comments on anything:

Comment.has_one :comment_commentee_tie CommentCommenteeTie belongs_to :comment belongs_to :commentee, polymorphic: true Post has_many :comment_commentee_ties
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Now let's say we want to filter comments by possible post data. To alleviate the joining, we can define a non-polymorphic association for Comment:

Comment has_one :comment_commentee_tie has_one :post, through: :comment_commentee_tie, source: :commentee, source_type: "Post"
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Polymorphic children

Let's look at the harder case with has_many :children, polymorphic: true

We can use the scope option to filter what types of children we want:

Parent has_many :parent_child_ties has_many( :good_children, -> { where(child_type: "GoodChild") }, through: :parent_child_ties, source: :child, source_type: "GoodChild" )
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