使用 SMT 创建订阅

import com.google.cloud.pubsub.v1.SubscriptionAdminClient;
import com.google.pubsub.v1.JavaScriptUDF;
import com.google.pubsub.v1.MessageTransform;
import com.google.pubsub.v1.ProjectSubscriptionName;
import com.google.pubsub.v1.ProjectTopicName;
import com.google.pubsub.v1.Subscription;
import java.io.IOException;

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

    createSubscriptionWithSmtExample(projectId, topicId, subscriptionId);
  }

  public static void createSubscriptionWithSmtExample(
      String projectId, String topicId, String subscriptionId) throws IOException {

    // UDF that removes the 'ssn' field, if present
    String code =
        "function redactSSN(message, metadata) {"
            + "  const data = JSON.parse(message.data);"
            + "  delete data['ssn'];"
            + "  message.data = JSON.stringify(data);"
            + "  return message;"
            + "}";
    String functionName = "redactSSN";

    JavaScriptUDF udf =
        JavaScriptUDF.newBuilder().setCode(code).setFunctionName(functionName).build();
    MessageTransform transform = MessageTransform.newBuilder().setJavascriptUdf(udf).build();

    try (SubscriptionAdminClient subscriptionAdminClient = SubscriptionAdminClient.create()) {

      ProjectTopicName topicName = ProjectTopicName.of(projectId, topicId);
      ProjectSubscriptionName subscriptionName =
          ProjectSubscriptionName.of(projectId, subscriptionId);

      Subscription subscription =
          subscriptionAdminClient.createSubscription(
              Subscription.newBuilder()
                  .setName(subscriptionName.toString())
                  .setTopic(topicName.toString())
                  // Add the UDF message transform
                  .addMessageTransforms(transform)
                  .build());

      System.out.println("Created subscription with SMT: " + subscription.getAllFields());
    }
  }
}

from google.cloud import pubsub_v1
from google.pubsub_v1.types import JavaScriptUDF, MessageTransform

# TODO(developer): Choose an existing topic.
# project_id = "your-project-id"
# topic_id = "your-topic-id"
# subscription_id = "your-subscription-id"

publisher = pubsub_v1.PublisherClient()
subscriber = pubsub_v1.SubscriberClient()
topic_path = publisher.topic_path(project_id, topic_id)
subscription_path = subscriber.subscription_path(project_id, subscription_id)

code = """function redactSSN(message, metadata) {
            const data = JSON.parse(message.data);
            delete data['ssn'];
            message.data = JSON.stringify(data);
            return message;
            }"""
udf = JavaScriptUDF(code=code, function_name="redactSSN")
transforms = [MessageTransform(javascript_udf=udf)]

with subscriber:
    subscription = subscriber.create_subscription(
        request={
            "name": subscription_path,
            "topic": topic_path,
            "message_transforms": transforms,
        }
    )
    print(f"Created subscription with SMT: {subscription}")

// Copyright 2025 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package subscriptions

import (
	"context"
	"fmt"
	"io"

	"cloud.google.com/go/pubsub"
)

// createSubscriptionWithSMT creates a subscription with a single message transform function applied.
func createSubscriptionWithSMT(w io.Writer, projectID, subID string, topic *pubsub.Topic) error {
	// projectID := "my-project-id"
	// subID := "my-sub"
	// topic of type https://godoc.org/cloud.google.com/go/pubsub#Topic
	ctx := context.Background()
	client, err := pubsub.NewClient(ctx, projectID)
	if err != nil {
		return fmt.Errorf("pubsub.NewClient: %w", err)
	}
	defer client.Close()

	code := `function redactSSN(message, metadata) {
			const data = JSON.parse(message.data);
			delete data['ssn'];
			message.data = JSON.stringify(data);
			return message;
		}`
	transform := pubsub.MessageTransform{
		Transform: pubsub.JavaScriptUDF{
			FunctionName: "redactSSN",
			Code:         code,
		},
	}
	cfg := pubsub.SubscriptionConfig{
		Topic:             topic,
		MessageTransforms: []pubsub.MessageTransform{transform},
	}
	sub, err := client.CreateSubscription(ctx, subID, cfg)
	if err != nil {
		return fmt.Errorf("CreateSubscription: %w", err)
	}
	fmt.Fprintf(w, "Created subscription with message transform: %v\n", sub)
	return nil
}