Get or create

Get or create in a transaction.

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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 .

  Entity 
  
 task 
 ; 
 using 
  
 ( 
 var 
  
 transaction 
  
 = 
  
 _db 
 . 
 BeginTransaction 
 ()) 
 { 
  
 task 
  
 = 
  
 transaction 
 . 
 Lookup 
 ( 
 _sampleTask 
 . 
 Key 
 ); 
  
 if 
  
 ( 
 task 
  
 == 
  
 null 
 ) 
  
 { 
  
 transaction 
 . 
 Insert 
 ( 
 _sampleTask 
 ); 
  
 transaction 
 . 
 Commit 
 (); 
  
 } 
 }

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 .

  _ 
 , 
  
 err 
  
 := 
  
 client 
 . 
 RunInTransaction 
 ( 
 ctx 
 , 
  
 func 
 ( 
 tx 
  
 * 
 datastore 
 . 
 Transaction 
 ) 
  
 error 
  
 { 
  
 var 
  
 task 
  
 Task 
  
 if 
  
 err 
  
 := 
  
 tx 
 . 
 Get 
 ( 
 key 
 , 
  
& task 
 ); 
  
 err 
  
 != 
  
 datastore 
 . 
 ErrNoSuchEntity 
  
 { 
  
 return 
  
 err 
  
 } 
  
 _ 
 , 
  
 err 
  
 := 
  
 tx 
 . 
 Put 
 ( 
 key 
 , 
  
& Task 
 { 
  
 Category 
 : 
  
 "Personal" 
 , 
  
 Done 
 : 
  
 false 
 , 
  
 Priority 
 : 
  
 4 
 , 
  
 Description 
 : 
  
 "Learn Cloud Datastore" 
 , 
  
 }) 
  
 return 
  
 err 
 })

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 .

  Entity 
  
 task 
 ; 
 Transaction 
  
 txn 
  
 = 
  
 datastore 
 . 
 newTransaction 
 (); 
 try 
  
 { 
  
 task 
  
 = 
  
 txn 
 . 
 get 
 ( 
 taskKey 
 ); 
  
 if 
  
 ( 
 task 
  
 == 
  
 null 
 ) 
  
 { 
  
 task 
  
 = 
  
 Entity 
 . 
 newBuilder 
 ( 
 taskKey 
 ). 
 build 
 (); 
  
 txn 
 . 
 put 
 ( 
 task 
 ); 
  
 txn 
 . 
 commit 
 (); 
  
 } 
 } 
  
 finally 
  
 { 
  
 if 
  
 ( 
 txn 
 . 
 isActive 
 ()) 
  
 { 
  
 txn 
 . 
 rollback 
 (); 
  
 } 
 }

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 
  
 getOrCreate 
 ( 
 taskKey 
 , 
  
 taskData 
 ) 
  
 { 
  
 const 
  
 taskEntity 
  
 = 
  
 { 
  
 key 
 : 
  
 taskKey 
 , 
  
 data 
 : 
  
 taskData 
 , 
  
 }; 
  
 const 
  
 transaction 
  
 = 
  
 datastore 
 . 
 transaction 
 (); 
  
 try 
  
 { 
  
 await 
  
 transaction 
 . 
 run 
 (); 
  
 const 
  
 [ 
 task 
 ] 
  
 = 
  
 await 
  
 transaction 
 . 
 get 
 ( 
 taskKey 
 ); 
  
 if 
  
 ( 
 task 
 ) 
  
 { 
  
 // The task entity already exists. 
  
 await 
  
 transaction 
 . 
 rollback 
 (); 
  
 } 
  
 else 
  
 { 
  
 // Create the task entity. 
  
 transaction 
 . 
 save 
 ( 
 taskEntity 
 ); 
  
 await 
  
 transaction 
 . 
 commit 
 (); 
  
 } 
  
 return 
  
 taskEntity 
 ; 
  
 } 
  
 catch 
  
 ( 
 err 
 ) 
  
 { 
  
 await 
  
 transaction 
 . 
 rollback 
 (); 
  
 } 
 }

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 .

  $transaction = $datastore->transaction(); 
 $entity = $transaction->lookup($task->key()); 
 if ($entity === null) { 
 $entity = $transaction->insert($task); 
 $transaction->commit(); 
 }

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 
 
 () 
 import 
  
 datetime 
 with 
 client 
 . 
  transaction 
 
 (): 
 key 
 = 
 client 
 . 
  key 
 
 ( 
 "Task" 
 , 
 datetime 
 . 
 datetime 
 . 
 now 
 ( 
 tz 
 = 
 datetime 
 . 
 timezone 
 . 
 utc 
 ) 
 . 
 isoformat 
 () 
 ) 
 task 
 = 
 client 
 . 
  get 
 
 ( 
 key 
 ) 
 if 
 not 
 task 
 : 
 task 
 = 
  datastore 
 
 . 
  Entity 
 
 ( 
 key 
 ) 
 task 
 . 
 update 
 ({ 
 "description" 
 : 
 "Example task" 
 }) 
 client 
 . 
  put 
 
 ( 
 task 
 ) 
 return 
 task

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 .

  task 
  
 = 
  
 nil 
 datastore 
 . 
 transaction 
  
 do 
  
 | 
 tx 
 | 
  
 task 
  
 = 
  
 tx 
 . 
 find 
  
 task_key 
  
 if 
  
 task 
 . 
 nil? 
  
 task 
  
 = 
  
 datastore 
 . 
 entity 
  
 task_key 
  
 do 
  
 | 
 t 
 | 
  
 t 
 [ 
 "category" 
 ] 
  
 = 
  
 "Personal" 
  
 t 
 [ 
 "done" 
 ] 
  
 = 
  
 false 
  
 t 
 [ 
 "priority" 
 ] 
  
 = 
  
 4 
  
 t 
 [ 
 "description" 
 ] 
  
 = 
  
 "Learn Cloud Datastore" 
  
 end 
  
 tx 
 . 
 save 
  
 task 
  
 end 
 end

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Explore further

Code sample

C#

Go

Java

Node.js

PHP

Python

Ruby

What's next

Get or create