Cloud Datastore Client - Class Query (1.24.4)

 use Google\Cloud\Datastore\DatastoreClient;

$datastore = new DatastoreClient();

$query = $datastore->query();
$query->kind('Companies');
$query->filter('companyName', '=', 'Google');

$res = $datastore->runQuery($query);
foreach ($res as $company) {
    echo $company['companyName']; // Google
} 

 // Queries can also be constructed using a
// [Query Object](https://cloud.google.com/datastore/reference/rest/v1/projects/runQuery#query):
$query = $datastore->query([
    'query' => [
        'kind' => [
            [
                'name' => 'Companies'
            ]
        ],
        'filter' => [
            'propertyFilter' => [
                'op' => 'EQUAL',
                'property' => [
                    'name' => 'companyName'
                ],
                'value' => [
                    'stringValue' => 'Google'
                ]
            ]
        ]
    ]
]); 

 $query->projection(['firstName', 'lastName']); 

 $query->keysOnly(); 

 $query->kind('Person'); 

 $key = $datastore->key('Person', 'Bob');
$query->hasAncestor($key); 

 // Specifying an identifier type
$key = $datastore->key('Robots', '1337', [
    'identifierType' => Key::TYPE_NAME
]);
$query->hasAncestor($key); 

 $query->distinctOn('lastName');