Property query

Use a property query

Explore further

For detailed documentation that includes this code sample, see the following:

• Datastore Metadata

Code sample

C#

To learn how to install and use the client library for Datastore mode, see Datastore mode client libraries. For more information, see the Datastore mode C# API reference documentation.

To authenticate to Datastore mode, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

Query query = new Query("__property__");
var properties = new List<string>();
foreach (Entity entity in _db.RunQuery(query).Entities)
{
    string kind = entity.Key.Path[0].Name;
    string property = entity.Key.Path[1].Name;
    if (kind == "Task")
        properties.Add(property);
};

Go

To learn how to install and use the client library for Datastore mode, see Datastore mode client libraries. For more information, see the Datastore mode Go API reference documentation.

To authenticate to Datastore mode, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

query := datastore.NewQuery("__property__").KeysOnly()
keys, err := client.GetAll(ctx, query, nil)
if err != nil {
	log.Fatalf("client.GetAll: %v", err)
}

props := make(map[string][]string) // Map from kind to slice of properties.
for _, k := range keys {
	prop := k.Name
	kind := k.Parent.Name
	props[kind] = append(props[kind], prop)
}

Java

To learn how to install and use the client library for Datastore mode, see Datastore mode client libraries. For more information, see the Datastore mode Java API reference documentation.

To authenticate to Datastore mode, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

Query<Key> query = Query.newKeyQueryBuilder().setKind("__property__").build();
QueryResults<Key> keys = datastore.run(query);
Map<String, Collection<String>> propertiesByKind = new HashMap<>();
while (keys.hasNext()) {
  Key key = keys.next();
  String kind = key.getParent().getName();
  String propertyName = key.getName();
  Collection<String> properties = propertiesByKind.get(kind);
  if (properties == null) {
    properties = new HashSet<>();
    propertiesByKind.put(kind, properties);
  }
  properties.add(propertyName);
}

Node.js

To learn how to install and use the client library for Datastore mode, see Datastore mode client libraries. For more information, see the Datastore mode Node.js API reference documentation.

To authenticate to Datastore mode, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

async function runPropertyQuery() {
  const query = datastore.createQuery('__property__').select('__key__');
  const [entities] = await datastore.runQuery(query);
  // @TODO convert below object to map
  const propertiesByKind = {};

  entities.forEach(entity => {
    const key = entity[datastore.KEY];
    const kind = key.path[1];
    const property = key.path[3];

    propertiesByKind[kind] = propertiesByKind[kind] || [];
    propertiesByKind[kind].push(property);
  });

  console.log('Properties by Kind:');
  for (const key in propertiesByKind) {
    console.log(key, propertiesByKind[key]);
  }

  return propertiesByKind;
}

PHP

To learn how to install and use the client library for Datastore mode, see Datastore mode client libraries. For more information, see the Datastore mode PHP API reference documentation.

To authenticate to Datastore mode, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

$query = $datastore->query()
    ->kind('__property__')
    ->projection(['__key__']);
$result = $datastore->runQuery($query);
/* @var array<string> $properties */
$properties = [];
/* @var Entity $entity */
foreach ($result as $entity) {
    $kind = $entity->key()->path()[0]['name'];
    $propertyName = $entity->key()->path()[1]['name'];
    $properties[] = "$kind.$propertyName";
}

Python

To learn how to install and use the client library for Datastore mode, see Datastore mode client libraries. For more information, see the Datastore mode Python API reference documentation.

To authenticate to Datastore mode, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

from google.cloud import datastore

# For help authenticating your client, visit
# https://cloud.google.com/docs/authentication/getting-started
client = datastore.Client()

from collections import defaultdict

query = client.query(kind="__property__")
query.keys_only()

properties_by_kind = defaultdict(list)

for entity in query.fetch():
    kind = entity.key.parent.name
    property_ = entity.key.name

    properties_by_kind[kind].append(property_)

Ruby

To learn how to install and use the client library for Datastore mode, see Datastore mode client libraries. For more information, see the Datastore mode Ruby API reference documentation.

To authenticate to Datastore mode, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

query = datastore.query("__property__")
                 .select("__key__")

entities = datastore.run query
properties_by_kind = entities.each_with_object({}) do |entity, memo|
  kind = entity.key.parent.name
  prop = entity.key.name
  memo[kind] ||= []
  memo[kind] << prop
end

What's next

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