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    List topics in project

    Lists topics in a project.

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

    Code sample

    C++

    Before trying this sample, follow the C++ setup instructions in the Pub/Sub quickstart using client libraries . For more information, see the Pub/Sub C++ API reference documentation .

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

      namespace 
  
 pubsub_admin 
  
 = 
  
 :: 
 google 
 :: 
 cloud 
 :: 
 pubsub_admin 
 ; 
 []( 
 pubsub_admin 
 :: 
 TopicAdminClient 
  
 client 
 , 
  
 std 
 :: 
 string 
  
 const 
&  
 project_id 
 ) 
  
 { 
  
 int 
  
 count 
  
 = 
  
 0 
 ; 
  
 for 
  
 ( 
 auto 
&  
 topic 
  
 : 
  
 client 
 . 
 ListTopics 
 ( 
 "projects/" 
  
 + 
  
 project_id 
 )) 
  
 { 
  
 if 
  
 ( 
 ! 
 topic 
 ) 
  
 throw 
  
 std 
 :: 
 move 
 ( 
 topic 
 ). 
 status 
 (); 
  
 std 
 :: 
 cout 
 << 
 "Topic Name: " 
 << 
 topic 
 - 
> name 
 () 
 << 
 " 
 \n 
 " 
 ; 
  
 ++ 
 count 
 ; 
  
 } 
  
 if 
  
 ( 
 count 
  
 == 
  
 0 
 ) 
  
 { 
  
 std 
 :: 
 cout 
 << 
 "No topics found in project " 
 << 
 project_id 
 << 
 " 
 \n 
 " 
 ; 
  
 } 
 }

    C#

    Before trying this sample, follow the C# setup instructions in the Pub/Sub quickstart using client libraries . For more information, see the Pub/Sub C# API reference documentation .

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

      using 
  
  Google.Api.Gax.ResourceNames 
 
 ; 
 using 
  
  Google.Cloud.PubSub.V1 
 
 ; 
 using 
  
 System.Collections.Generic 
 ; 
 public 
  
 class 
  
 ListProjectTopicsSample 
 { 
  
 public 
  
 IEnumerable<Topic> 
  
 ListProjectTopics 
 ( 
 string 
  
 projectId 
 ) 
  
 { 
  
  PublisherServiceApiClient 
 
  
 publisher 
  
 = 
  
  PublisherServiceApiClient 
 
 . 
  Create 
 
 (); 
  
  ProjectName 
 
  
 projectName 
  
 = 
  
  ProjectName 
 
 . 
  FromProject 
 
 ( 
 projectId 
 ); 
  
 IEnumerable<Topic> 
  
 topics 
  
 = 
  
 publisher 
 . 
  ListTopics 
 
 ( 
 projectName 
 ); 
  
 return 
  
 topics 
 ; 
  
 } 
 }

    Go

    Before trying this sample, follow the Go setup instructions in the Pub/Sub quickstart using client libraries . For more information, see the Pub/Sub Go API reference documentation .

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

      import 
  
 ( 
  
 "context" 
  
 "fmt" 
  
 "io" 
  
 "cloud.google.com/go/pubsub/v2" 
  
 "cloud.google.com/go/pubsub/v2/apiv1/pubsubpb" 
  
 "google.golang.org/api/iterator" 
 ) 
 func 
  
 listTopics 
 ( 
 w 
  
 io 
 . 
 Writer 
 , 
  
 projectID 
  
 string 
 ) 
  
 error 
  
 { 
  
 // projectID := "my-project-id" 
  
 ctx 
  
 := 
  
 context 
 . 
 Background 
 () 
  
 client 
 , 
  
 err 
  
 := 
  
 pubsub 
 . 
 NewClient 
 ( 
 ctx 
 , 
  
 projectID 
 ) 
  
 if 
  
 err 
  
 != 
  
 nil 
  
 { 
  
 return 
  
 fmt 
 . 
 Errorf 
 ( 
 "pubsub.NewClient: %w" 
 , 
  
 err 
 ) 
  
 } 
  
 defer 
  
 client 
 . 
 Close 
 () 
  
 req 
  
 := 
  
& pubsubpb 
 . 
 ListTopicsRequest 
 { 
  
 Project 
 : 
  
 fmt 
 . 
 Sprintf 
 ( 
 "projects/%s" 
 , 
  
 projectID 
 ), 
  
 } 
  
 it 
  
 := 
  
 client 
 . 
 TopicAdminClient 
 . 
 ListTopics 
 ( 
 ctx 
 , 
  
 req 
 ) 
  
 for 
  
 { 
  
 topic 
 , 
  
 err 
  
 := 
  
 it 
 . 
 Next 
 () 
  
 if 
  
 err 
  
 == 
  
 iterator 
 . 
 Done 
  
 { 
  
 break 
  
 } 
  
 if 
  
 err 
  
 != 
  
 nil 
  
 { 
  
 return 
  
 fmt 
 . 
 Errorf 
 ( 
 "error listing topics: %w" 
 , 
  
 err 
 ) 
  
 } 
  
 fmt 
 . 
 Fprintf 
 ( 
 w 
 , 
  
 "got topic: %s\n" 
 , 
  
 topic 
 ) 
  
 } 
  
 return 
  
 nil 
 }

    Java

    Before trying this sample, follow the Java setup instructions in the Pub/Sub quickstart using client libraries . For more information, see the Pub/Sub Java API reference documentation .

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

      import 
  
 com.google.cloud.pubsub.v1. TopicAdminClient 
 
 ; 
 import 
  
 com.google.pubsub.v1. ProjectName 
 
 ; 
 import 
  
 com.google.pubsub.v1. Topic 
 
 ; 
 import 
  
 java.io.IOException 
 ; 
 public 
  
 class 
 ListTopicsExample 
  
 { 
  
 public 
  
 static 
  
 void 
  
 main 
 ( 
 String 
 ... 
  
 args 
 ) 
  
 throws 
  
 Exception 
  
 { 
  
 // TODO(developer): Replace these variables before running the sample. 
  
 String 
  
 projectId 
  
 = 
  
 "your-project-id" 
 ; 
  
 listTopicsExample 
 ( 
 projectId 
 ); 
  
 } 
  
 public 
  
 static 
  
 void 
  
 listTopicsExample 
 ( 
 String 
  
 projectId 
 ) 
  
 throws 
  
 IOException 
  
 { 
  
 try 
  
 ( 
  TopicAdminClient 
 
  
 topicAdminClient 
  
 = 
  
  TopicAdminClient 
 
 . 
 create 
 ()) 
  
 { 
  
  ProjectName 
 
  
 projectName 
  
 = 
  
  ProjectName 
 
 . 
 of 
 ( 
 projectId 
 ); 
  
 for 
  
 ( 
  Topic 
 
  
 topic 
  
 : 
  
 topicAdminClient 
 . 
 listTopics 
 ( 
 projectName 
 ). 
 iterateAll 
 ()) 
  
 { 
  
 System 
 . 
 out 
 . 
 println 
 ( 
 topic 
 . 
 getName 
 ()); 
  
 } 
  
 System 
 . 
 out 
 . 
 println 
 ( 
 "Listed all topics." 
 ); 
  
 } 
  
 } 
 }

    Node.js

    Before trying this sample, follow the Node.js setup instructions in the Pub/Sub quickstart using client libraries . For more information, see the Pub/Sub Node.js API reference documentation .

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

      // 
  
 Imports 
  
 the 
  
 Google 
  
 Cloud 
  
 client 
  
 library 
 const 
  
 { 
 PubSub 
 } 
  
 = 
  
 require 
 ( 
 '@google-cloud/pubsub' 
 ); 
 // 
  
 Creates 
  
 a 
  
 client 
 ; 
  
 cache 
  
 this 
  
 for 
  
 further 
  
 use 
 const 
  
 pubSubClient 
  
 = 
  
 new 
  
 PubSub 
 (); 
 async 
  
 function 
  
 listAllTopics 
 () 
  
 { 
  
 // 
  
 Lists 
  
 all 
  
 topics 
  
 in 
  
 the 
  
 current 
  
 project 
  
 const 
  
 [ 
 topics 
 ] 
  
 = 
  
 await 
  
 pubSubClient 
 . 
 getTopics 
 (); 
  
 console 
 . 
 log 
 ( 
 'Topics:' 
 ); 
  
 topics 
 . 
 forEach 
 ( 
 topic 
  
 = 
>  
 console 
 . 
 log 
 ( 
 topic 
 . 
 name 
 )); 
 }

    Node.js

    Before trying this sample, follow the Node.js setup instructions in the Pub/Sub quickstart using client libraries . For more information, see the Pub/Sub Node.js API reference documentation .

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

      // 
 Imports 
 the 
 Google 
 Cloud 
 client 
 library 
 import 
  
 { 
 PubSub 
 , 
 Topic 
 } 
 from 
  
 '@google-cloud/pubsub' 
 ; 
 // 
 Creates 
 a 
 client 
 ; 
 cache 
 this 
 for 
 further 
 use 
 const 
 pubSubClient 
 = 
 new 
 PubSub 
 (); 
 async 
 function 
 listAllTopics 
 () 
 { 
 // 
 Lists 
 all 
 topics 
 in 
 the 
 current 
 project 
 const 
 [ 
 topics 
 ] 
 = 
 await 
 pubSubClient 
 . 
 getTopics 
 (); 
 console 
 . 
 log 
 ( 
 'Topics:' 
 ); 
 topics 
 . 
 forEach 
 (( 
 topic 
 : 
 Topic 
 ) 
 = 
> console 
 . 
 log 
 ( 
 topic 
 . 
 name 
 )); 
 }

    PHP

    Before trying this sample, follow the PHP setup instructions in the Pub/Sub quickstart using client libraries . For more information, see the Pub/Sub PHP API reference documentation .

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

      use Google\Cloud\PubSub\PubSubClient; 
 /** 
 * Lists all Pub/Sub topics. 
 * 
 * @param string $projectId  The Google project ID. 
 */ 
 function list_topics($projectId) 
 { 
 $pubsub = new PubSubClient([ 
 'projectId' => $projectId, 
 ]); 
 foreach ($pubsub->topics() as $topic) { 
 printf('Topic: %s' . PHP_EOL, $topic->name()); 
 } 
 }

    Python

    Before trying this sample, follow the Python setup instructions in the Pub/Sub quickstart using client libraries . For more information, see the Pub/Sub Python API reference documentation .

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

      from 
  
 google.cloud 
  
 import 
 pubsub_v1 
 # TODO(developer) 
 # project_id = "your-project-id" 
 publisher 
 = 
 pubsub_v1 
 . 
  PublisherClient 
 
 () 
 project_path 
 = 
 f 
 "projects/ 
 { 
 project_id 
 } 
 " 
 for 
 topic 
 in 
 publisher 
 . 
 list_topics 
 ( 
 request 
 = 
 { 
 "project" 
 : 
 project_path 
 }): 
 print 
 ( 
 topic 
 )

    Ruby

    Before trying this sample, follow the Ruby setup instructions in the Pub/Sub quickstart using client libraries . For more information, see the Pub/Sub Ruby API reference documentation .

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

      pubsub 
  
 = 
  
 Google 
 :: 
 Cloud 
 :: 
  PubSub 
 
 . 
  new 
 
 topic_admin 
  
 = 
  
 pubsub 
 . 
  topic_admin 
 
 topics 
  
 = 
  
 topic_admin 
 . 
 list_topics 
  
 project 
 : 
  
 pubsub 
 . 
 project_path 
 puts 
  
 "Topics in project:" 
 topics 
 . 
 each 
  
 do 
  
 | 
 topic 
 | 
  
 puts 
  
 topic 
 . 
 name 
 end

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