List schemas for a topic

This document shows you how to list schemas for Pub/Sub topics.

Before you begin

Required roles and permissions

To get the permissions that you need to list schemas and manage them, ask your administrator to grant you the Pub/Sub Editor (roles/pubsub.editor) IAM role on your project. For more information about granting roles, see Manage access to projects, folders, and organizations.

This predefined role contains the permissions required to list schemas and manage them. To see the exact permissions that are required, expand the Required permissions section:

Required permissions

The following permissions are required to list schemas and manage them:

  • Create schema: pubsub.schemas.create
  • Attach schema to topic: pubsub.schemas.attach
  • Commit a schema revision: pubsub.schemas.commit
  • Delete a schema or a schema revision: pubsub.schemas.delete
  • Get a schema or schema revisions: pubsub.schemas.get
  • List schemas: pubsub.schemas.list
  • List schema revisions: pubsub.schemas.listRevisions
  • Rollback a schema: pubsub.schemas.rollback
  • Validate a message: pubsub.schemas.validate
  • Get the IAM policy for a schema: pubsub.schemas.getIamPolicy
  • Configure the IAM policy for a schema: pubsub.schemas.setIamPolicy

You might also be able to get these permissions with custom roles or other predefined roles.

You can grant roles and permissions to principals such as users, groups, domains, or service accounts. You can create a schema in one project and attach it to a topic located in a different project. Ensure that you have the required permissions for each project.

List schemas

You can list the schemas in a Google Cloud project using the Google Cloud console, the gcloud CLI, the Pub/Sub API, or the Cloud Client Libraries.

Console

  • In the Google Cloud console, go to the Pub/Sub schemas page.

    Go to Schemas

    The list of schemas is displayed.

gcloud

gcloud pubsub schemas list

Use the gcloud pubsub schemas list --view=FULL command to see the latest definition for each schema.

REST

To list the schemas in a project, send a GET request like the following:

GET https://pubsub.googleapis.com/v1/projects/PROJECT_ID/schemas

If successful, the response body contains a JSON object containing the latest revision for all schemas in the project.

C++

Before trying this sample, follow the C++ setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub C++ API reference documentation. 

namespace pubsub = ::google::cloud::pubsub;
[](pubsub::SchemaServiceClient client, std::string const& project_id) {
  auto const parent = google::cloud::Project(project_id).FullName();
  for (auto& s : client.ListSchemas(parent)) {
    if (!s) throw std::move(s).status();
    std::cout << "Schema: " << s->DebugString() << "\n";
  }
}

C#

Before trying this sample, follow the C# setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub C# API reference documentation. 


using Google.Api.Gax.ResourceNames;
using Google.Cloud.PubSub.V1;
using System.Collections.Generic;

public class ListSchemasSample
{
    public IEnumerable<Schema> ListSchemas(string projectId)
    {
        SchemaServiceClient schemaService = SchemaServiceClient.Create();
        ProjectName projectName = ProjectName.FromProject(projectId);
        var schemas = schemaService.ListSchemas(projectName);
        return schemas;
    }
}

Go

Before trying this sample, follow the Go setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub Go API reference documentation. 

import (
	"context"
	"fmt"
	"io"

	"cloud.google.com/go/pubsub"
	"google.golang.org/api/iterator"
)

func listSchemas(w io.Writer, projectID string) ([]*pubsub.SchemaConfig, error) {
	// projectID := "my-project-id"
	ctx := context.Background()
	client, err := pubsub.NewSchemaClient(ctx, projectID)
	if err != nil {
		return nil, fmt.Errorf("pubsub.NewSchemaClient: %w", err)
	}
	defer client.Close()

	var schemas []*pubsub.SchemaConfig

	schemaIter := client.Schemas(ctx, pubsub.SchemaViewFull)
	for {
		sc, err := schemaIter.Next()
		if err == iterator.Done {
			break
		}
		if err != nil {
			return nil, fmt.Errorf("schemaIter.Next: %w", err)
		}
		fmt.Fprintf(w, "Got schema: %#v\n", sc)
		schemas = append(schemas, sc)
	}

	fmt.Fprintf(w, "Got %d schemas", len(schemas))
	return schemas, nil
}

Java

Before trying this sample, follow the Java setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub Java API reference documentation. 

import com.google.cloud.pubsub.v1.SchemaServiceClient;
import com.google.pubsub.v1.ProjectName;
import com.google.pubsub.v1.Schema;
import java.io.IOException;

public class ListSchemasExample {
  public static void main(String... args) throws Exception {
    // TODO(developer): Replace these variables before running the sample.
    String projectId = "your-project-id";

    listSchemasExample(projectId);
  }

  public static void listSchemasExample(String projectId) throws IOException {
    ProjectName projectName = ProjectName.of(projectId);

    try (SchemaServiceClient schemaServiceClient = SchemaServiceClient.create()) {
      for (Schema schema : schemaServiceClient.listSchemas(projectName).iterateAll()) {
        System.out.println(schema);
      }
      System.out.println("Listed schemas.");
    }
  }
}

Node.js

Before trying this sample, follow the Node.js setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub Node.js API reference documentation. 


// 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 listSchemas() {
  for await (const s of pubSubClient.listSchemas()) {
    console.log(s.name);
  }
  console.log('Listed schemas.');
}

Node.js

Before trying this sample, follow the Node.js setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub Node.js API reference documentation. 


// Imports the Google Cloud client library
import {PubSub} from '@google-cloud/pubsub';

// Creates a client; cache this for further use
const pubSubClient = new PubSub();

async function listSchemas() {
  for await (const s of pubSubClient.listSchemas()) {
    console.log(s.name);
  }
  console.log('Listed schemas.');
}

PHP

Before trying this sample, follow the PHP setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub PHP API reference documentation. 

use Google\Cloud\PubSub\PubSubClient;

/**
 * List schemas in the project.
 *
 * @param string $projectId
 */
function list_schemas($projectId)
{
    $pubsub = new PubSubClient([
        'projectId' => $projectId,
    ]);

    $schemas = $pubsub->schemas();
    foreach ($schemas as $schema) {
        printf('Schema name: %s' . PHP_EOL, $schema->name());
    }
}

Python

Before trying this sample, follow the Python setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub Python API reference documentation. 

from google.cloud.pubsub import SchemaServiceClient

# TODO(developer): Replace these variables before running the sample.
# project_id = "your-project-id"

project_path = f"projects/{project_id}"
schema_client = SchemaServiceClient()

for schema in schema_client.list_schemas(request={"parent": project_path}):
    print(schema)

print("Listed schemas.")

Ruby

Before trying this sample, follow the Ruby setup instructions in Quickstart: Using Client Libraries. For more information, see the Pub/Sub Ruby API reference documentation. 


pubsub = Google::Cloud::Pubsub.new

schemas = pubsub.schemas

puts "Schemas in project:"
schemas.each do |schema|
  puts schema.name
end

What's next