Reference documentation and code samples for the Cloud Datastore Client class Key.

Keys are unique identifiers for entities.

Keys may be considered either "named" or "incomplete". A named Key is one inwhich each element of the Key path specify a Kind and a Name or ID. Anincomplete Key omits the Name or ID from the final path element.

Named Keys are required for any lookup, update, upsert or delete operations.They may also be used for inserting records, so long as you are certain thatthe identifier is available in Datastore.

Incomplete Keys may be used for inserting records into Datastore. When anincomplete Key is used, Datastore will allocate an ID before inserting.

Incomplete Keys are useful for guaranteeing the availability of an identifierwithout requiring an additional operation to check whether a given name or IDis available.

Key state can be checked by callingKey::state(). The return will be one ofKey::STATE_NAMED orKey::STATE_INCOMPLETE.

Example:

use Google\Cloud\Datastore\DatastoreClient;$datastore = new DatastoreClient();$key = $datastore->key('Person', 'Bob');

// Keys with complex paths can be constructed with additional method calls.$key = $datastore->key('Person', 'Bob');$key->ancestor('Parents', 'Joe');$key->ancestor('Grandparents', 'Barb');

// Path elements can also be appended, so long as the current last path// element contains a kind and identifier.$key = $datastore->key('Grandparents', 'Barb');$key->pathElement('Parents', 'Joe');$key->pathElement('Person');$key->pathElement('Child', 'Dave'); // Error here.

Create a Key.