List Lite topics

List Lite topics in a project.

Explore further

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

• Create and manage Lite topics

Code sample

Go

To authenticate to Pub/Sub Lite, 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/pubsublite"
	"google.golang.org/api/iterator"
)

func listTopics(w io.Writer, projectID, region, zone string) error {
	// projectID := "my-project-id"
	// region := "us-central1"
	// zone := "us-central1-a"
	ctx := context.Background()
	client, err := pubsublite.NewAdminClient(ctx, region)
	if err != nil {
		return fmt.Errorf("pubsublite.NewAdminClient: %w", err)
	}
	defer client.Close()

	parent := fmt.Sprintf("projects/%s/locations/%s", projectID, zone)
	topicIter := client.Topics(ctx, parent)
	for {
		topic, err := topicIter.Next()
		if err == iterator.Done {
			break
		}
		if err != nil {
			return fmt.Errorf("topicIter.Next got err: %w", err)
		}
		fmt.Fprintf(w, "Got topic: %#v\n", topic)
	}
	return nil
}

Java

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

import com.google.cloud.pubsublite.AdminClient;
import com.google.cloud.pubsublite.AdminClientSettings;
import com.google.cloud.pubsublite.CloudRegion;
import com.google.cloud.pubsublite.CloudRegionOrZone;
import com.google.cloud.pubsublite.CloudZone;
import com.google.cloud.pubsublite.LocationPath;
import com.google.cloud.pubsublite.ProjectNumber;
import com.google.cloud.pubsublite.proto.Topic;
import java.util.List;

public class ListTopicsExample {

  public static void main(String... args) throws Exception {
    // TODO(developer): Replace these variables before running the sample.
    String cloudRegion = "your-cloud-region";
    char zoneId = 'b';
    long projectNumber = Long.parseLong("123456789");
    // True if using a regional location. False if using a zonal location.
    // https://cloud.google.com/pubsub/lite/docs/topics
    boolean regional = true;

    listTopicsExample(cloudRegion, zoneId, projectNumber, regional);
  }

  public static void listTopicsExample(
      String cloudRegion, char zoneId, long projectNumber, boolean regional) throws Exception {

    AdminClientSettings adminClientSettings =
        AdminClientSettings.newBuilder().setRegion(CloudRegion.of(cloudRegion)).build();

    CloudRegionOrZone location;
    if (regional) {
      location = CloudRegionOrZone.of(CloudRegion.of(cloudRegion));
    } else {
      location = CloudRegionOrZone.of(CloudZone.of(CloudRegion.of(cloudRegion), zoneId));
    }

    LocationPath locationPath =
        LocationPath.newBuilder()
            .setProject(ProjectNumber.of(projectNumber))
            .setLocation(location)
            .build();

    try (AdminClient adminClient = AdminClient.create(adminClientSettings)) {
      List<Topic> topics = adminClient.listTopics(locationPath).get();
      for (Topic topic : topics) {
        System.out.println(topic.getAllFields());
      }
      System.out.println(topics.size() + " topic(s) listed.");
    }
  }
}

Python

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

from google.cloud.pubsublite import AdminClient
from google.cloud.pubsublite.types import CloudRegion, CloudZone, LocationPath

# TODO(developer):
# project_number = 1122334455
# cloud_region = "us-central1"
# zone_id = "a"
# regional = True

location = None
if regional:
    #  A region.
    location = CloudRegion(cloud_region)
else:
    #  A zone.
    location = CloudZone(CloudRegion(cloud_region), zone_id)

location_path = LocationPath(project_number, location)

client = AdminClient(cloud_region)
response = client.list_topics(location_path)

for topic in response:
    print(topic)

print(f"{len(response)} topic(s) listed in your project and location.")

What's next

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