Property by kind query

Query property by kind.

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.

Key key = _db.CreateKeyFactory("__kind__").CreateKey("Task");
Query query = new Query("__property__")
{
    Filter = Filter.HasAncestor(key)
};
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;
    var representations = entity["property_representation"]
        .ArrayValue.Values.Select(x => x.StringValue)
        .OrderBy(x => x);
    properties.Add($"{property}:" +
        string.Join(",", representations));
};

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.

kindKey := datastore.NameKey("__kind__", "Task", nil)
query := datastore.NewQuery("__property__").Ancestor(kindKey)

type Prop struct {
	Repr []string `datastore:"property_representation"`
}

var props []Prop
keys, err := client.GetAll(ctx, query, &props)

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.

Key key = datastore.newKeyFactory().setKind("__kind__").newKey("Task");
Query<Entity> query =
    Query.newEntityQueryBuilder()
        .setKind("__property__")
        .setFilter(PropertyFilter.hasAncestor(key))
        .build();
QueryResults<Entity> results = datastore.run(query);
Map<String, Collection<String>> representationsByProperty = new HashMap<>();
while (results.hasNext()) {
  Entity result = results.next();
  String propertyName = result.getKey().getName();
  List<StringValue> representations = result.getList("property_representation");
  Collection<String> currentRepresentations = representationsByProperty.get(propertyName);
  if (currentRepresentations == null) {
    currentRepresentations = new HashSet<>();
    representationsByProperty.put(propertyName, currentRepresentations);
  }
  for (StringValue value : representations) {
    currentRepresentations.add(value.get());
  }
}

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 runPropertyByKindQuery() {
  const ancestorKey = datastore.key(['__kind__', 'Account']);

  const query = datastore
    .createQuery('__property__')
    .hasAncestor(ancestorKey);
  const [entities] = await datastore.runQuery(query);

  const representationsByProperty = {};

  entities.forEach(entity => {
    const key = entity[datastore.KEY];
    const propertyName = key.name;
    const propertyType = entity.property_representation;

    representationsByProperty[propertyName] = propertyType;
  });

  console.log('Task property representations:');
  for (const key in representationsByProperty) {
    console.log(key, representationsByProperty[key]);
  }

  return representationsByProperty;
}

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.

$ancestorKey = $datastore->key('__kind__', 'Task');
$query = $datastore->query()
    ->kind('__property__')
    ->hasAncestor($ancestorKey);
$result = $datastore->runQuery($query);
/* @var array<string,string> $properties */
$properties = [];
/* @var Entity $entity */
foreach ($result as $entity) {
    $propertyName = $entity->key()->path()[1]['name'];
    $propertyType = $entity['property_representation'];
    $properties[$propertyName] = $propertyType;
}
// Example values of $properties: ['description' => ['STRING']]

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()

ancestor = client.key("__kind__", "Task")
query = client.query(kind="__property__", ancestor=ancestor)

representations_by_property = {}

for entity in query.fetch():
    property_name = entity.key.name
    property_types = entity["property_representation"]

    representations_by_property[property_name] = property_types

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.

ancestor_key = datastore.key "__kind__", "Task"
query = datastore.query("__property__")
                 .ancestor(ancestor_key)

entities = datastore.run query
representations = entities.each_with_object({}) do |entity, memo|
  property_name = entity.key.name
  property_types = entity["property_representation"]
  memo[property_name] = property_types
end

What's next

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