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    Property query

    Use a property query

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

    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

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