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38eec0ba86
improvement: support `mix ash.rollback` with interactive rollback
23 lines
1.2 KiB
Markdown
23 lines
1.2 KiB
Markdown
# References
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To configure the behavior of generated foreign keys on a resource, we use the `references` section.
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For example:
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```elixir
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references do
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reference :post, on_delete: :delete, on_update: :update, name: "comments_to_posts_fkey"
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end
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```
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> ### Actions are not used for this behavior {: .warning}
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>
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> No resource logic is applied with these operations! No authorization rules or validations take place, and no notifications are issued. This operation happens *directly* in the database.
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## Nothing vs Restrict
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The difference between `:nothing` and `:restrict` is subtle and, if you are unsure, choose `:nothing` (the default behavior). `:restrict` will prevent the deletion from happening *before* the end of the database transaction, whereas `:nothing` allows the transaction to complete before doing so. This allows for things like updating or deleting the destination row and *then* updating updating or deleting the reference(as long as you are in a transaction).
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## On Delete
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This option is called `on_delete`, instead of `on_destroy`, because it is hooking into the database level deletion, *not* a `destroy` action in your resource. See the warning above.
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