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22 lines
719 B
Markdown
22 lines
719 B
Markdown
# [Optimistic Lock](https://en.wikipedia.org/wiki/Optimistic_concurrency_control) Using Hooks
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In this example, we implement an optimistic locking mechanism using an `ent.Hook`.
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The idea is to add to our schema a `version` field that holds the Unix time of when the latest update occurred.
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When an `UpdateOne` operation is executed, the hook updates the `version` field with the new value and adds a predicate
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to verify that the `version` wasn't updated by another process/transaction during the mutation.
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An error is returned if the versions are mismatched, and the user should reload the entity and retry the mutation.
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### Generate Assets
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```console
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go generate ./...
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```
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### Run Example
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```console
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go test
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```
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