Avoiding extra queries in belongs_to relationship management

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1

I have an update action on an Ash resource that manages a belongs_to relationship:

    change manage_relationship(:business, type: :append_and_remove)

I’ve noticed that when the attributes and relationship arguments passed in to the update action result in no change - no SQL update - multiple SQL select queries run anyway to check the relationships.

How might I side-step the relationship management when the foreign key is not changing, so that the relationship management queries are skipped?

2

Hm…seems like maybe something that it should be doing by default. But in terms of how you can do it yourself, your best bet would be switching to a custom change, like:

change fn changeset, _ -> 
  new_business_id = changeset.arguments[:business_id]
  if new_business_id && new_business_id != changeset.data.business_id do
    Ash.Changeset.manage_relationship(changeset, :business, ....)
  else
    changeset
  end
end
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