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https://github.com/silverstripe/silverstripe-framework
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49 lines
1.5 KiB
Markdown
49 lines
1.5 KiB
Markdown
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---
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title: Generating Unique Keys
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summary: Outputting unique keys in templates.
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icon: code
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---
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# Unique Keys
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There are several cases where you may want to generate a unique key. For example:
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* populate `ID` attribute in your HTML output
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* key for partial cache
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This can be done simply by including following code in your template:
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```ss
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$DataObject.UniqueKey
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```
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`getUniqueKey` method is available on `DataObject` so you can use it on many object types like pages and blocks.
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## Customisation
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The unique key generation can be altered in two ways:
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* you can provide extra data to be used when generating a key via an extension
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* you can inject over the key generation service and write your own custom code
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### Extension point
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`cacheKeyComponent` extension point is located in `DataObject::getUniqueKeyComponents`.
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Use standard extension flow to define the `cacheKeyComponent` method on your extension which is expected to return a `string`.
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This value will be used when unique key is generated. Common cases are:
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* versions - object in different version stages needs to have different unique keys
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* locales - object in different locales needs to have different unique keys
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### Custom service
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`UniqueKeyService` is used by default but you can use injector to override it with your custom service. For example:
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```yaml
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SilverStripe\Core\Injector\Injector:
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SilverStripe\ORM\UniqueKey\UniqueKeyService:
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class: App\Service\MyCustomService
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```
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Your custom service has to implement `UniqueKeyInterface`.
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