AE
Ash Elixir•2y ago
WIGGLES

Polymorphic Self References

Can't seem to figure out how to accomplish the following. I have a polymorphic table that is meant to model a tree relationship. this of course requires a belongs_to and has_many relationship to itself. How do I go about defining a self referential relationship that is mean to pickup on context provided by the consumer? Such that all the relationships are within the same table? 
relationships do
    belongs_to :parent, __MODULE__
    has_many :children, __MODULE__, destination_attribute: :parent_id
end

postgres do
  polymorphic? true

  repo Butsby.Repo

  references do
    reference :parent, on_delete: :delete
  end
end
relationships do
    belongs_to :parent, __MODULE__
    has_many :children, __MODULE__, destination_attribute: :parent_id
end

postgres do
  polymorphic? true

  repo Butsby.Repo

  references do
    reference :parent, on_delete: :delete
  end
end
3 Replies
WIGGLES
WIGGLESOP•2y ago
My guess is that this is where I want to reach for manual relationships? No I guess that doesn't work since the foreign key constraint will never be set. I guess I might not be able to use polymorphic resources for this.
ZachDaniel
ZachDaniel•2y ago
Yeah, I haven’t considered this use case TBH. We could maybe work something up but I don’t think it's supported currently. You might need to define each resource manually.
WIGGLES
WIGGLESOP•2y ago
I think all I really want to do is to pass on what the consumer specifies in the data_layer context but I guess I can write a macro module to generate the resources for me. In the meantime I'll probably write up a feature request on the github.

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