Add API for checking uniqueness constraints for updates #1140
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Entities which are already in the DB will conflict with themselves when using `checkUnique`, unless the value of each unique key is changed. This adds an alternative `checkUniqueUpdateable` which ignores conflicts from an entity with itself, so that uniqueness constraints can be checked without an update.
parsonsmatt
approved these changes
Oct 26, 2020
| Nothing -> checkUniqueKeysUpdateable key xs | ||
| Just (Entity k _) | ||
| | key == k -> checkUniqueKeysUpdateable key xs | ||
| Just _ -> return (Just x) |
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This is fantastic, thanks!
| -- | ||
| -- While this would be 'Just' because SPJ already exists: | ||
| -- | ||
| -- > mSpjConst <- checkUnique $ User "SPJ" 60 |
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Awesome docs, thanks 😄
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I can't take the credit - these are largely copied from checkUnique, plus a paragraph on the difference in behaviour.
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Alright, I've added a test for the basic behaviour - an entity not clashing with itself, but still clashing with other entities. |
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Looks great, thanks so much! |
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Entities which are already in the DB will conflict with themselves when using
checkUnique, unless the value of each unique key is changed. This adds an alternativecheckUniqueUpdateablewhich ignores conflicts from an entity with itself, so that uniqueness constraints can be checked without an update.Before submitting your PR, check that you've:
@sincedeclarations to the HaddockAfter submitting your PR:
(unreleased)on the Changelog