Namespace query

Namespace 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 .

  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 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 .

  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 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 .

  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 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 
  
 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 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('__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 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 
 
 () 
 # 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 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 
 ( 
 "__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

What's next

To search and filter code samples for other Google Cloud products, see the Google Cloud sample browser .

Namespace query Stay organized with collections Save and categorize content based on your preferences.

Explore further

Code sample

C#

Go

Java

Node.js

PHP

Python

Ruby

What's next

Namespace query