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37 lines
1.1 KiB
Markdown
37 lines
1.1 KiB
Markdown
# Atomics
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Atomics allow you to attach expression-based changes to changesets, to be executed in the data layer when the action is performed.
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For example:
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```elixir
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update :increment_score do
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argument :points, :integer, allow_nil?: false
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change atomic_update(:score, expr(score + ^arg(:points)))
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end
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```
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## What is supported
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- Atomics are only supported in update actions and upserts. In the case of upserts, the atomic changes are only applied in the case of a conflicting record.
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- Attaching atomics to an action using the `atomic_update/2` change in the action, as shown in the example below.
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- Attaching atomics to a changeset manually with `Ash.Changeset.atomic_update/3`
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- Using calculations that don't refer to aggregates or related values in expressions
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### Manually attached
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```elixir
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changeset
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|> Ash.Changeset.atomic_update(:score, Ash.Expr.expr(score + 1))
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|> Api.update!()
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```
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### Upsert example
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```elixir
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create :upsert do
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upsert? true
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change set_attribute(:points, 1) # set to 1
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set_on_upsert :points, expr(points + 1) # or increment existing
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end
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```
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