如果pubsub主题不可用，则引发未找到异常 [英] throw not found exception if pubsub topic is not available

问题描述

我正在使用Spring Boot与pubsub主题进行交互.

I am using spring boot to interact with pubsub topic.

此连接的配置类如下:

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.cloud.gcp.pubsub.core.PubSubTemplate;
import org.springframework.cloud.gcp.pubsub.core.publisher.PubSubPublisherTemplate;
import org.springframework.cloud.gcp.pubsub.support.PublisherFactory;
import org.springframework.cloud.gcp.pubsub.support.converter.SimplePubSubMessageConverter;
import org.springframework.util.Assert;
import org.springframework.util.concurrent.ListenableFuture;
import org.springframework.util.concurrent.SettableListenableFuture;

import com.google.api.core.ApiFuture;
import com.google.api.core.ApiFutureCallback;
import com.google.api.core.ApiFutures;
import com.google.pubsub.v1.PubsubMessage;

public abstract class PubSubPublisher {

    private static final Logger LOGGER = LoggerFactory.getLogger(PubSubPublisher.class);

    private final PubSubTemplate pubSubTemplate;


    protected PubSubPublisher(PubSubTemplate pubSubTemplate) {
        this.pubSubTemplate = pubSubTemplate;
    }

    protected abstract String topic(String topicName);

    public  ListenableFuture<String> publish(String topicName, String message) {
        LOGGER.info("Publishing to topic [{}]. Message: [{}]", topicName, message);
        return pubSubTemplate.publish(topicName, message);
    }

}

我正在为我服务，就像这样:

And I am calling this at my service, like this:

publisher.publish(topic-name, payload);

此发布方法是异步方法，该方法始终传递未等待确认.我在发布后进行添加获取，等待它获得pubsub的响应.

This publish method is async one, which always pass on did not wait for acknowldgrment. I make add get after publish for wait until it get the response from pubsub.

但是我想知道如果我的主题不存在并且我尝试推送一些消息，它应该抛出一些错误，例如找不到资源，而只考虑使用默认的异步方法.

But I wanted to know if in case my topic is not already present and i try to push some message, it should throw some error like resource not found, considering using default async method only.

可能实现回调将有所帮助，但是我无法在我的代码中做到这一点.并且当前使用回调的重写发布方法只是抛出WARN not exception，我希望将其作为例外.这就是我想要实现回调的原因.

Might be implementing the callback would help but i am unable to do that in my code. And the current override publish method which use callback is just throwing the WARN not exception i wanted that to be exception. that is the reason i wanted to implement the callback.

推荐答案

您可以检查主题是否已存在

You can check if Topic already present

from google.cloud import pubsub_v1

project_id = "projectname"
topic_name = "unknowTopic"

publisher = pubsub_v1.PublisherClient()
topic_path = publisher.topic_path(project_id, topic_name)
try:
    response = publisher.get_topic(topic_path)
except Exception as e:
    print(e)

这将错误返回为

404 Resource not found (resource=unknowTopic).

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