Unique keys#

There are several cases where you may want to generate a unique key. For example:

• populate ID attribute in your HTML output
• key for partial cache

If this is for a public-facing purpose, it is typically considered bad practice to expose the database ID, as this provides unnecessary information to would-be attackers. Instead, for DataObject subclasses, you can use the getUniqueKey() method.

This can be done simply by including following code in your template:

$UniqueKey

Customisation#

The unique key generation can be altered in two ways:

1. you can provide extra data to be used when generating a key via an extension
2. you can inject over the key generation service and write your own custom code.

Extension point#

The cacheKeyComponent extension hook is invoked from DataObject::getUniqueKeyComponents(). Simply implement a cacheKeyComponent() method in an Extension applied to the DataObject class you want to affect. The method must return a string, which will be used when generating a unique key for the record.

Some cases where this is used in supported modules already are:

• versions - an object in different version stages needs to have different unique keys for each stage
• locales - an object in different locales needs to have different unique keys for each locale

See Extensions for more information about implementing and applying extensions.

Custom service#

UniqueKeyService is used by default but you can use injector to override it with your custom service. For example:

SilverStripe\Core\Injector\Injector:
  SilverStripe\ORM\UniqueKey\UniqueKeyService:
    class: App\Service\MyCustomService

Your custom service has to implement UniqueKeyInterface.

A use case for implementing your own service might be to produce a UUID for each record.