Subscribe with a filter to an Amazon SNS topic using an Amazon SDK

Subscribe a queue to a topic with optional filters.

    /// <summary>
    /// Subscribe a queue to a topic with optional filters.
    /// </summary>
    /// <param name="topicArn">The ARN of the topic.</param>
    /// <param name="useFifoTopic">The optional filtering policy for the subscription.</param>
    /// <param name="queueArn">The ARN of the queue.</param>
    /// <returns>The ARN of the new subscription.</returns>
    public async Task<string> SubscribeTopicWithFilter(string topicArn, string? filterPolicy, string queueArn)
    {
        var subscribeRequest = new SubscribeRequest()
        {
            TopicArn = topicArn,
            Protocol = "sqs",
            Endpoint = queueArn
        };

        if (!string.IsNullOrEmpty(filterPolicy))
        {
            subscribeRequest.Attributes = new Dictionary<string, string> { { "FilterPolicy", filterPolicy } };
        }

        var subscribeResponse = await _amazonSNSClient.SubscribeAsync(subscribeRequest);
        return subscribeResponse.SubscriptionArn;
    }

        static const Aws::String TONE_ATTRIBUTE("tone");
        static const Aws::Vector<Aws::String> TONES = {"cheerful", "funny", "serious",
                                                       "sincere"};

        Aws::Client::ClientConfiguration clientConfig;
        // Optional: Set to the AWS Region (overrides config file).
        // clientConfig.region = "us-east-1";

    Aws::SNS::SNSClient snsClient(clientConfiguration);

            Aws::SNS::Model::SubscribeRequest request;
            request.SetTopicArn(topicARN);
            request.SetProtocol("sqs");
            request.SetEndpoint(queueARN);
            if (isFifoTopic) {
                if (first) {
                    std::cout << "Subscriptions to a FIFO topic can have filters."
                              << std::endl;
                    std::cout
                            << "If you add a filter to this subscription, then only the filtered messages "
                            << "will be received in the queue." << std::endl;
                    std::cout << "For information about message filtering, "
                              << "see https://docs.aws.amazon.com/sns/latest/dg/sns-message-filtering.html"
                              << std::endl;
                    std::cout << "For this example, you can filter messages by a \""
                              << TONE_ATTRIBUTE << "\" attribute." << std::endl;
                }

                std::ostringstream ostringstream;
                ostringstream << "Filter messages for \"" << queueName
                              << "\"'s subscription to the topic \""
                              << topicName << "\"?  (y/n)";

                // Add filter if user answers yes.
                if (askYesNoQuestion(ostringstream.str())) {
                    Aws::String jsonPolicy = getFilterPolicyFromUser();
                    if (!jsonPolicy.empty()) {
                        filteringMessages = true;

                        std::cout << "This is the filter policy for this subscription."
                                  << std::endl;
                        std::cout << jsonPolicy << std::endl;

                        request.AddAttributes("FilterPolicy", jsonPolicy);
                    }
                    else {
                        std::cout
                                << "Because you did not select any attributes, no filter "
                                << "will be added to this subscription." << std::endl;
                    }
                }
            }  // if (isFifoTopic)
            Aws::SNS::Model::SubscribeOutcome outcome = snsClient.Subscribe(request);

            if (outcome.IsSuccess()) {
                Aws::String subscriptionARN = outcome.GetResult().GetSubscriptionArn();
                std::cout << "The queue '" << queueName
                          << "' has been subscribed to the topic '"
                          << "'" << topicName << "'" << std::endl;
                std::cout << "with the subscription ARN '" << subscriptionARN << "."
                          << std::endl;
                subscriptionARNS.push_back(subscriptionARN);
            }
            else {
                std::cerr << "Error with TopicsAndQueues::Subscribe. "
                          << outcome.GetError().GetMessage()
                          << std::endl;

                cleanUp(topicARN,
                        queueURLS,
                        subscriptionARNS,
                        snsClient,
                        sqsClient);

                return false;
            }

//! Routine that lets the user select attributes for a subscription filter policy.
/*!
 \sa getFilterPolicyFromUser()
 \return Aws::String: The filter policy as JSON.
 */
Aws::String AwsDoc::TopicsAndQueues::getFilterPolicyFromUser() {
    std::cout
            << "You can filter messages by one or more of the following \""
            << TONE_ATTRIBUTE << "\" attributes." << std::endl;

    std::vector<Aws::String> filterSelections;
    int selection;
    do {
        for (size_t j = 0; j < TONES.size(); ++j) {
            std::cout << "  " << (j + 1) << ". " << TONES[j]
                      << std::endl;
        }
        selection = askQuestionForIntRange(
                "Enter a number (or enter zero to stop adding more). ",
                0, static_cast<int>(TONES.size()));

        if (selection != 0) {
            const Aws::String &selectedTone(TONES[selection - 1]);
            // Add the tone to the selection if it is not already added.
            if (std::find(filterSelections.begin(),
                          filterSelections.end(),
                          selectedTone)
                == filterSelections.end()) {
                filterSelections.push_back(selectedTone);
            }
        }
    } while (selection != 0);

    Aws::String result;
    if (!filterSelections.empty()) {
        std::ostringstream jsonPolicyStream;
        jsonPolicyStream << "{ \"" << TONE_ATTRIBUTE << "\": [";


        for (size_t j = 0; j < filterSelections.size(); ++j) {
            jsonPolicyStream << "\"" << filterSelections[j] << "\"";
            if (j < filterSelections.size() - 1) {
                jsonPolicyStream << ",";
            }
        }
        jsonPolicyStream << "] }";

        result = jsonPolicyStream.str();
    }

    return result;
}

import { SubscribeCommand, SNSClient } from "@aws-sdk/client-sns";

const client = new SNSClient({});

export const subscribeQueueFiltered = async (
  topicArn = "TOPIC_ARN",
  queueArn = "QUEUE_ARN"
) => {
  const command = new SubscribeCommand({
    TopicArn: topicArn,
    Protocol: "sqs",
    Endpoint: queueArn,
    Attributes: {
      // This subscription will only receive messages with the 'event' attribute set to 'order_placed'.
      FilterPolicyScope: "MessageAttributes",
      FilterPolicy: JSON.stringify({
        event: ["order_placed"],
      }),
    },
  });

  const response = await client.send(command);
  console.log(response);
  // {
  //   '$metadata': {
  //     httpStatusCode: 200,
  //     requestId: '931e13d9-5e2b-543f-8781-4e9e494c5ff2',
  //     extendedRequestId: undefined,
  //     cfId: undefined,
  //     attempts: 1,
  //     totalRetryDelay: 0
  //   },
  //   SubscriptionArn: 'arn:aws:sns:us-east-1:xxxxxxxxxxxx:subscribe-queue-test-430895:xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx'
  // }
  return response;
};