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    Datastore Metadata

    Firestore in Datastore mode provides access to metadata that includes information about entity groups, namespaces, entity kinds, properties, and property representations for each property. You can use metadata, for example, to build a custom datastore viewer for your application or for backend administrative functions.

    The Datastore Dashboard in the Google Cloud console also provides some metadata about your application, but the data displayed there differs in some important respects from that returned by these functions.

    • Freshness.Reading metadata using the API gets current data, whereas data in the dashboard is updated only once daily.
    • Contents.Some metadata in the dashboard is not available through the APIs; the reverse is also true.
    • Speed.Metadata gets and queries are billed in the same way as datastore gets and queries . Metadata queries that fetch information on namespaces, kinds, and properties are generally slow to execute. As a rule of thumb, expect a metadata query that returns N entities to take about the same time as N ordinary queries each returning a single entity. Furthermore, property representation queries (non-keys-only property queries) are slower than keys-only property queries . Metadata gets of entity group metadata are somewhat faster than getting a regular entity.

    Metadata queries

    Three special entity kinds are reserved for metadata queries:

    Entity Description
    __namespace__ Used to find all the namespaces used in your application entities.
    __kind__ Used to query a specific kind.
    __property__ Used to query by a property of a kind.

    These kinds will not conflict with others of the same names that may already exist in your application. By querying on these special kinds, you can retrieve entities containing the desired metadata.

    The entities returned by metadata queries are generated dynamically, based on the current state of your database. While you can create local entity objects of kinds __namespace__ , __kind__ , or __property__ , any attempt to store them in the database will fail.

    Namespace queries

    You can use a namespace query to find all namespaces used in the application's entities. This allows you to perform activities such as administrative functions across multiple namespaces.

    Namespace queries return entities of the special kind __namespace__ whose key name is the name of a namespace. (An exception is the default namespace designated by the empty string "" : since the empty string is not a valid key name, this namespace is keyed with the numeric ID 1 instead.) Queries of this type support filtering only for ranges over the special pseudoproperty __key__ , whose value is the entity's key. The results can be sorted by ascending (but not descending) __key__ value. Because __namespace__ entities have no properties, both keys-only and non-keys-only queries return the same information.

    The following example returns a list of an application's namespaces in the range between the values assigned to the startNamespace and endNamespace variables:

    C#

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

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

      KeyFactory 
  
 keyFactory 
  
 = 
  
 _db 
 . 
 CreateKeyFactory 
 ( 
 "__namespace__" 
 ); 
 // List all the namespaces between a lower and upper bound. 
 string 
  
 lowerBound 
  
 = 
  
 _db 
 . 
 NamespaceId 
 . 
 Substring 
 ( 
 0 
 , 
  
 _db 
 . 
 NamespaceId 
 . 
 Length 
  
 - 
  
 1 
 ); 
 string 
  
 upperBound 
  
 = 
  
 _db 
 . 
 NamespaceId 
  
 + 
  
 "z" 
 ; 
 Key 
  
 startNamespace 
  
 = 
  
 keyFactory 
 . 
 CreateKey 
 ( 
 lowerBound 
 ); 
 Key 
  
 endNamespace 
  
 = 
  
 keyFactory 
 . 
 CreateKey 
 ( 
 upperBound 
 ); 
 Query 
  
 query 
  
 = 
  
 new 
  
 Query 
 ( 
 "__namespace__" 
 ) 
 { 
  
 Filter 
  
 = 
  
 Filter 
 . 
 And 
 ( 
  
 Filter 
 . 
 GreaterThan 
 ( 
 "__key__" 
 , 
  
 startNamespace 
 ), 
  
 Filter 
 . 
 LessThan 
 ( 
 "__key__" 
 , 
  
 endNamespace 
 )) 
 }; 
 var 
  
 namespaces 
  
 = 
  
 new 
  
 List<string> 
 (); 
 foreach 
  
 ( 
 Entity 
  
 entity 
  
 in 
  
 _db 
 . 
 RunQuery 
 ( 
 query 
 ). 
 Entities 
 ) 
 { 
  
 namespaces 
 . 
 Add 
 ( 
 entity 
 . 
 Key 
 . 
 Path 
 [ 
 0 
 ]. 
 Name 
 ); 
 };

    Go

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

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

      func 
  
 metadataNamespaces 
 ( 
 w 
  
 io 
 . 
 Writer 
 , 
  
 projectID 
  
 string 
 ) 
  
 error 
  
 { 
  
 // projectID := "my-project" 
  
 ctx 
  
 := 
  
 context 
 . 
 Background 
 () 
  
 client 
 , 
  
 err 
  
 := 
  
 datastore 
 . 
 NewClient 
 ( 
 ctx 
 , 
  
 projectID 
 ) 
  
 if 
  
 err 
  
 != 
  
 nil 
  
 { 
  
 return 
  
 fmt 
 . 
 Errorf 
 ( 
 "datastore.NewClient: %w" 
 , 
  
 err 
 ) 
  
 } 
  
 defer 
  
 client 
 . 
 Close 
 () 
  
 start 
  
 := 
  
 datastore 
 . 
 NameKey 
 ( 
 "__namespace__" 
 , 
  
 "g" 
 , 
  
 nil 
 ) 
  
 end 
  
 := 
  
 datastore 
 . 
 NameKey 
 ( 
 "__namespace__" 
 , 
  
 "h" 
 , 
  
 nil 
 ) 
  
 query 
  
 := 
  
 datastore 
 . 
 NewQuery 
 ( 
 "__namespace__" 
 ). 
  
 FilterField 
 ( 
 "__key__" 
 , 
  
 ">=" 
 , 
  
 start 
 ). 
  
 FilterField 
 ( 
 "__key__" 
 , 
  
 "<" 
 , 
  
 end 
 ). 
  
 KeysOnly 
 () 
  
 keys 
 , 
  
 err 
  
 := 
  
 client 
 . 
 GetAll 
 ( 
 ctx 
 , 
  
 query 
 , 
  
 nil 
 ) 
  
 if 
  
 err 
  
 != 
  
 nil 
  
 { 
  
 return 
  
 fmt 
 . 
 Errorf 
 ( 
 "client.GetAll: %w" 
 , 
  
 err 
 ) 
  
 } 
  
 fmt 
 . 
 Fprintln 
 ( 
 w 
 , 
  
 "Namespaces:" 
 ) 
  
 for 
  
 _ 
 , 
  
 k 
  
 := 
  
 range 
  
 keys 
  
 { 
  
 fmt 
 . 
 Fprintf 
 ( 
 w 
 , 
  
 "\t%v" 
 , 
  
 k 
 . 
 Name 
 ) 
  
 } 
  
 return 
  
 nil 
 }

    Java

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

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

      KeyFactory 
  
 keyFactory 
  
 = 
  
 datastore 
 . 
 newKeyFactory 
 (). 
 setKind 
 ( 
 "__namespace__" 
 ); 
 Key 
  
 startNamespace 
  
 = 
  
 keyFactory 
 . 
 newKey 
 ( 
 "g" 
 ); 
 Key 
  
 endNamespace 
  
 = 
  
 keyFactory 
 . 
 newKey 
 ( 
 "h" 
 ); 
 Query<Key> 
  
 query 
  
 = 
  
 Query 
 . 
 newKeyQueryBuilder 
 () 
  
 . 
 setKind 
 ( 
 "__namespace__" 
 ) 
  
 . 
 setFilter 
 ( 
  
 CompositeFilter 
 . 
 and 
 ( 
  
 PropertyFilter 
 . 
 gt 
 ( 
 "__key__" 
 , 
  
 startNamespace 
 ), 
  
 PropertyFilter 
 . 
 lt 
 ( 
 "__key__" 
 , 
  
 endNamespace 
 ))) 
  
 . 
 build 
 (); 
 List<String> 
  
 namespaces 
  
 = 
  
 new 
  
 ArrayList 
<> (); 
 QueryResults<Key> 
  
 results 
  
 = 
  
 datastore 
 . 
 run 
 ( 
 query 
 ); 
 while 
  
 ( 
 results 
 . 
 hasNext 
 ()) 
  
 { 
  
 namespaces 
 . 
 add 
 ( 
 results 
 . 
 next 
 (). 
 getName 
 ()); 
 }

    Node.js

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

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

      async 
  
 function 
  
 runNamespaceQuery 
 ( 
 startNamespace 
 , 
  
 endNamespace 
 ) 
  
 { 
  
 const 
  
 startKey 
  
 = 
  
 datastore 
 . 
 key 
 ([ 
 '__namespace__' 
 , 
  
 startNamespace 
 ]); 
  
 const 
  
 endKey 
  
 = 
  
 datastore 
 . 
 key 
 ([ 
 '__namespace__' 
 , 
  
 endNamespace 
 ]); 
  
 const 
  
 query 
  
 = 
  
 datastore 
  
 . 
 createQuery 
 ( 
 '__namespace__' 
 ) 
  
 . 
 select 
 ( 
 '__key__' 
 ) 
  
 . 
 filter 
 ( 
  
 and 
 ([ 
  
 new 
  
 PropertyFilter 
 ( 
 '__key__' 
 , 
  
 '>=' 
 , 
  
 startKey 
 ), 
  
 new 
  
 PropertyFilter 
 ( 
 '__key__' 
 , 
  
 '<' 
 , 
  
 endKey 
 ), 
  
 ]), 
  
 ); 
  
 const 
  
 [ 
 entities 
 ] 
  
 = 
  
 await 
  
 datastore 
 . 
 runQuery 
 ( 
 query 
 ); 
  
 const 
  
 namespaces 
  
 = 
  
 entities 
 . 
 map 
 ( 
 entity 
  
 = 
>  
 entity 
 [ 
 datastore 
 . 
 KEY 
 ]. 
 name 
 ); 
  
 console 
 . 
 log 
 ( 
 'Namespaces:' 
 ); 
  
 namespaces 
 . 
 forEach 
 ( 
 namespace 
  
 = 
>  
 console 
 . 
 log 
 ( 
 namespace 
 )); 
  
 return 
  
 namespaces 
 ; 
 }

    PHP

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

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

      $query = $datastore->query() 
 ->kind('__namespace__') 
 ->projection(['__key__']) 
 ->filter('__key__', '>=', $datastore->key('__namespace__', $start)) 
 ->filter('__key__', '<', $datastore->key('__namespace__', $end)); 
 $result = $datastore->runQuery($query); 
 /* @var array<string> $namespaces */ 
 $namespaces = []; 
 foreach ($result as $namespace) { 
 $namespaces[] = $namespace->key()->pathEnd()['name']; 
 }

    Python

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

    To authenticate to Cloud Datastore, 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 
 
 () 
 # All namespaces 
 query 
 = 
 client 
 . 
  query 
 
 ( 
 kind 
 = 
 "__namespace__" 
 ) 
 query 
 . 
  keys_only 
 
 () 
 all_namespaces 
 = 
 [ 
 entity 
 . 
 key 
 . 
  id_or_name 
 
 for 
 entity 
 in 
 query 
 . 
 fetch 
 ()] 
 # Filtered namespaces 
 start_namespace 
 = 
 client 
 . 
  key 
 
 ( 
 "__namespace__" 
 , 
 "g" 
 ) 
 end_namespace 
 = 
 client 
 . 
  key 
 
 ( 
 "__namespace__" 
 , 
 "h" 
 ) 
 query 
 = 
 client 
 . 
  query 
 
 ( 
 kind 
 = 
 "__namespace__" 
 ) 
 query 
 . 
  key_filter 
 
 ( 
 start_namespace 
 , 
 ">=" 
 ) 
 query 
 . 
  key_filter 
 
 ( 
 end_namespace 
 , 
 "<" 
 ) 
 filtered_namespaces 
 = 
 [ 
 entity 
 . 
 key 
 . 
  id_or_name 
 
 for 
 entity 
 in 
 query 
 . 
 fetch 
 ()]

    Ruby

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

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

      query 
  
 = 
  
 datastore 
 . 
 query 
 ( 
 "__namespace__" 
 ) 
  
 . 
 select 
 ( 
 "__key__" 
 ) 
  
 . 
 where 
 ( 
 "__key__" 
 , 
  
 ">=" 
 , 
  
 datastore 
 . 
 key 
 ( 
 "__namespace__" 
 , 
  
 "g" 
 )) 
  
 . 
 where 
 ( 
 "__key__" 
 , 
  
 "<" 
 , 
  
 datastore 
 . 
 key 
 ( 
 "__namespace__" 
 , 
  
 "h" 
 )) 
 namespaces 
  
 = 
  
 datastore 
 . 
 run 
 ( 
 query 
 ) 
 . 
 map 
  
 do 
  
 | 
 entity 
 | 
  
 entity 
 . 
 key 
 . 
 name 
 end

    GQL 

     SELECT 
  
 __key__ 
  
 FROM 
  
 __namespace__ 
 WHERE 
  
 __key__ 
  
> = 
  
 KEY 
 ( 
 __namespace__ 
 , 
  
 'namespace-a' 
 ) 
  
 AND 
  
 __key__ 
 < 
 KEY 
 ( 
 __namespace__ 
 , 
  
 'namespace-b' 
 )

    Kind queries

    Kind queries return entities of kind __kind__ whose key name is the name of an entity kind. Queries of this type are implicitly restricted to the current namespace and support filtering only for ranges over the __key__ pseudoproperty. The results can be sorted by ascending (but not descending) __key__ value. Because __kind__ entities have no properties, both keys-only and non-keys-only queries return the same information.

    The following example prints a list of the kinds used in an application:

    C#

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

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

      Query 
  
 query 
  
 = 
  
 new 
  
 Query 
 ( 
 "__kind__" 
 ); 
 var 
  
 kinds 
  
 = 
  
 new 
  
 List<string> 
 (); 
 foreach 
  
 ( 
 Entity 
  
 entity 
  
 in 
  
 _db 
 . 
 RunQuery 
 ( 
 query 
 ). 
 Entities 
 ) 
 { 
  
 kinds 
 . 
 Add 
 ( 
 entity 
 . 
 Key 
 . 
 Path 
 [ 
 0 
 ]. 
 Name 
 ); 
 };

    Go

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

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

      query 
  
 := 
  
 datastore 
 . 
 NewQuery 
 ( 
 "__kind__" 
 ). 
 KeysOnly 
 () 
 keys 
 , 
  
 err 
  
 := 
  
 client 
 . 
 GetAll 
 ( 
 ctx 
 , 
  
 query 
 , 
  
 nil 
 ) 
 if 
  
 err 
  
 != 
  
 nil 
  
 { 
  
 log 
 . 
 Fatalf 
 ( 
 "client.GetAll: %v" 
 , 
  
 err 
 ) 
 } 
 kinds 
  
 := 
  
 make 
 ([] 
 string 
 , 
  
 0 
 , 
  
 len 
 ( 
 keys 
 )) 
 for 
  
 _ 
 , 
  
 k 
  
 := 
  
 range 
  
 keys 
  
 { 
  
 kinds 
  
 = 
  
 append 
 ( 
 kinds 
 , 
  
 k 
 . 
 Name 
 ) 
 }

    Java

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

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

      Query<Key> 
  
 query 
  
 = 
  
 Query 
 . 
 newKeyQueryBuilder 
 (). 
 setKind 
 ( 
 "__kind__" 
 ). 
 build 
 (); 
 List<String> 
  
 kinds 
  
 = 
  
 new 
  
 ArrayList 
<> (); 
 QueryResults<Key> 
  
 results 
  
 = 
  
 datastore 
 . 
 run 
 ( 
 query 
 ); 
 while 
  
 ( 
 results 
 . 
 hasNext 
 ()) 
  
 { 
  
 kinds 
 . 
 add 
 ( 
 results 
 . 
 next 
 (). 
 getName 
 ()); 
 }

    Node.js

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

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

      async 
  
 function 
  
 runKindQuery 
 () 
  
 { 
  
 const 
  
 query 
  
 = 
  
 datastore 
 . 
 createQuery 
 ( 
 '__kind__' 
 ). 
 select 
 ( 
 '__key__' 
 ); 
  
 const 
  
 [ 
 entities 
 ] 
  
 = 
  
 await 
  
 datastore 
 . 
 runQuery 
 ( 
 query 
 ); 
  
 const 
  
 kinds 
  
 = 
  
 entities 
 . 
 map 
 ( 
 entity 
  
 = 
>  
 entity 
 [ 
 datastore 
 . 
 KEY 
 ]. 
 name 
 ); 
  
 console 
 . 
 log 
 ( 
 'Kinds:' 
 ); 
  
 kinds 
 . 
 forEach 
 ( 
 kind 
  
 = 
>  
 console 
 . 
 log 
 ( 
 kind 
 )); 
  
 return 
  
 kinds 
 ; 
 }

    PHP

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

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

      $query = $datastore->query() 
 ->kind('__kind__') 
 ->projection(['__key__']); 
 $result = $datastore->runQuery($query); 
 /* @var array<string> $kinds */ 
 $kinds = []; 
 foreach ($result as $kind) { 
 $kinds[] = $kind->key()->pathEnd()['name']; 
 }

    Python

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

    To authenticate to Cloud Datastore, 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 
 
 () 
 query 
 = 
 client 
 . 
  query 
 
 ( 
 kind 
 = 
 "__kind__" 
 ) 
 query 
 . 
  keys_only 
 
 () 
 kinds 
 = 
 [ 
 entity 
 . 
 key 
 . 
  id_or_name 
 
 for 
 entity 
 in 
 query 
 . 
 fetch 
 ()]

    Ruby

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

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

      query 
  
 = 
  
 datastore 
 . 
 query 
 ( 
 "__kind__" 
 ) 
  
 . 
 select 
 ( 
 "__key__" 
 ) 
 kinds 
  
 = 
  
 datastore 
 . 
 run 
 ( 
 query 
 ) 
 . 
 map 
  
 do 
  
 | 
 entity 
 | 
  
 entity 
 . 
 key 
 . 
 name 
 end

    GQL 

     SELECT 
  
 __key__ 
  
 FROM 
  
 __kind__

    Property queries

    Property queries return entities of kind __property__ denoting the indexed properties associated with an entity kind. (Unindexed properties are not included.) The entity representing property p of kind k is built as follows:

    • The entity's key has kind __property__ and key name p .
    • The entity's parent key has kind __kind__ and key name k .
    • The entity's property_representation array property contains all the property's representations .

    For example, if your database contains exactly two Task entities with name and done properties:

     Key: 'Task:1'
name: 'Read some properties'
done: true

Key: 'Task:2'
name: 'Climb'
done: null

    then the two entities returned by a __property__ query will be:

     Key: '__kind__:Task/__property__:name'
property_representation: [ 'STRING' ]

Key: '__kind__:Task/__property__:done'
property_representation: [ 'BOOLEAN', 'NULL' ]

    Property queries are implicitly restricted to the current namespace, and support limited filtering with an ancestor or a range over the __key__ pseudoproperty.

    A keys-only property query is more efficient than a non-keys-only query, as it does not need to collect the property's representations. The following example retrieves the names of all of an application's entity kinds and the properties associated with each:

    C#

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

    To authenticate to Cloud Datastore, 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 Cloud Datastore, see Cloud Datastore client libraries . For more information, see the Cloud Datastore Go API reference documentation .

    To authenticate to Cloud Datastore, 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 Cloud Datastore, see Cloud Datastore client libraries . For more information, see the Cloud Datastore Java API reference documentation .

    To authenticate to Cloud Datastore, 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 Cloud Datastore, see Cloud Datastore client libraries . For more information, see the Cloud Datastore Node.js API reference documentation .

    To authenticate to Cloud Datastore, 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 Cloud Datastore, see Cloud Datastore client libraries . For more information, see the Cloud Datastore PHP API reference documentation .

    To authenticate to Cloud Datastore, 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 Cloud Datastore, see Cloud Datastore client libraries . For more information, see the Cloud Datastore Python API reference documentation .

    To authenticate to Cloud Datastore, 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 Cloud Datastore, see Cloud Datastore client libraries . For more information, see the Cloud Datastore Ruby API reference documentation .

    To authenticate to Cloud Datastore, 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

    GQL 

     SELECT 
  
 __key__ 
  
 FROM 
  
 __property__

    Property queries: property representations

    Non-keys-only property queries, known as property representation queries , return additional information on the value types used for each property. The property_representation property in the entity representing property p of kind k is an array containing all representations of p 's value in any entity of kind k .

    Each value has the following representation (note that some value types share representations):

    Value type Representation
    Integer INT64
    Floating-point number DOUBLE
    Boolean BOOLEAN
    Text string STRING
    Byte string STRING
    Date and time INT64
    Datastore key REFERENCE
    Embedded entity STRING
    Array representation of the array's elements
    Geographical point POINT
    Null NULL

    The following example finds all representations of properties of kind Task , using an ancestor property query :

    C#

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

    To authenticate to Cloud Datastore, 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 Cloud Datastore, see Cloud Datastore client libraries . For more information, see the Cloud Datastore Go API reference documentation .

    To authenticate to Cloud Datastore, 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 Cloud Datastore, see Cloud Datastore client libraries . For more information, see the Cloud Datastore Java API reference documentation .

    To authenticate to Cloud Datastore, 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 Cloud Datastore, see Cloud Datastore client libraries . For more information, see the Cloud Datastore Node.js API reference documentation .

    To authenticate to Cloud Datastore, 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 Cloud Datastore, see Cloud Datastore client libraries . For more information, see the Cloud Datastore PHP API reference documentation .

    To authenticate to Cloud Datastore, 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 Cloud Datastore, see Cloud Datastore client libraries . For more information, see the Cloud Datastore Python API reference documentation .

    To authenticate to Cloud Datastore, 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 Cloud Datastore, see Cloud Datastore client libraries . For more information, see the Cloud Datastore Ruby API reference documentation .

    To authenticate to Cloud Datastore, 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

    GQL 

     SELECT 
  
 * 
  
 FROM 
  
 __property__ 
 WHERE 
  
 __key__ 
  
 HAS 
  
 ANCESTOR 
  
 KEY 
 ( 
 __kind__ 
 , 
  
 'Task' 
 )

    Property queries: filtering

    Property queries support ancestor filtering on a __kind__ or __property__ key, to limit the query results to a single kind or property, as seen in the property representation query above.

    Property queries can also be filtered with a range over the pseudoproperty __key__ , where the keys denote either __kind__ or __property__ entities. The results can be sorted by ascending (but not descending) __key__ value. Filtering is applied to kind-property pairs, ordered first by kind and second by property. For instance, suppose you have entities with these properties:

    • kind Task with properties
      • created
      • priority
      • tags
    • kind TaskList with properties
      • created

    The following keys-only property query:

    C#

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

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

      Key 
  
 key 
  
 = 
  
 _db 
 . 
 CreateKeyFactory 
 ( 
 "__kind__" 
 ). 
 CreateKey 
 ( 
 "Task" 
 ); 
 Key 
  
 startKey 
  
 = 
  
 new 
  
 KeyFactory 
 ( 
 key 
 , 
  
 "__property__" 
 ) 
  
 . 
 CreateKey 
 ( 
 "priority" 
 ); 
 Query 
  
 query 
  
 = 
  
 new 
  
 Query 
 ( 
 "__property__" 
 ) 
 { 
  
 Filter 
  
 = 
  
 Filter 
 . 
 GreaterThanOrEqual 
 ( 
 "__key__" 
 , 
  
 startKey 
 ) 
 }; 
 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 
 ; 
  
 properties 
 . 
 Add 
 ( 
 $"{kind}.{property}" 
 ); 
 };

    Go

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

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

    Not Applicable

    Java

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

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

      Key 
  
 startKey 
  
 = 
  
 datastore 
  
 . 
 newKeyFactory 
 () 
  
 . 
 setKind 
 ( 
 "__property__" 
 ) 
  
 . 
 addAncestors 
 ( 
 PathElement 
 . 
 of 
 ( 
 "__kind__" 
 , 
  
 "Task" 
 )) 
  
 . 
 newKey 
 ( 
 "priority" 
 ); 
 Query<Key> 
  
 query 
  
 = 
  
 Query 
 . 
 newKeyQueryBuilder 
 () 
  
 . 
 setKind 
 ( 
 "__property__" 
 ) 
  
 . 
 setFilter 
 ( 
 PropertyFilter 
 . 
 ge 
 ( 
 "__key__" 
 , 
  
 startKey 
 )) 
  
 . 
 build 
 (); 
 Map<String 
 , 
  
 Collection<String> 
>  
 propertiesByKind 
  
 = 
  
 new 
  
 HashMap 
<> (); 
 QueryResults<Key> 
  
 keys 
  
 = 
  
 datastore 
 . 
 run 
 ( 
 query 
 ); 
 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<String> 
 (); 
  
 propertiesByKind 
 . 
 put 
 ( 
 kind 
 , 
  
 properties 
 ); 
  
 } 
  
 properties 
 . 
 add 
 ( 
 propertyName 
 ); 
 }

    Node.js

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

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

    Not Applicable

    PHP

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

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

      $ancestorKey = $datastore->key('__kind__', 'Task'); 
 $startKey = $datastore->key('__property__', 'priority') 
 ->ancestorKey($ancestorKey); 
 $query = $datastore->query() 
 ->kind('__property__') 
 ->filter('__key__', '>=', $startKey); 
 $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 Cloud Datastore, see Cloud Datastore client libraries . For more information, see the Cloud Datastore Python API reference documentation .

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

    Not Applicable

    Ruby

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

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

      start_key 
  
 = 
  
 datastore 
 . 
 key 
  
 [[ 
 "__kind__" 
 , 
  
 "Task" 
 ] 
 , 
  
 [ 
 "__property__" 
 , 
  
 "priority" 
 ]] 
 query 
  
 = 
  
 datastore 
 . 
 query 
 ( 
 "__property__" 
 ) 
  
 . 
 select 
 ( 
 "__key__" 
 ) 
  
 . 
 where 
 ( 
 "__key__" 
 , 
  
 ">=" 
 , 
  
 start_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

    GQL 

     SELECT 
  
 __key__ 
  
 FROM 
  
 __property__ 
 WHERE 
  
 __key__ 
  
> = 
  
 KEY 
 ( 
 __kind__ 
 , 
  
 'Task' 
 , 
  
 __property__ 
 , 
  
 'priority' 
 )

    will collect the following kind, property name pairs:

     Task, priority
Task, tags
TaskList, created

    Notice that the results include properties from kinds Task and TaskList , but do not include the created property of kind Task , because it falls outside the range specified for the query.
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