如何从云功能中提取pub/sub消息

Question

我想使用云函数从pub/sub中提取消息。所以我设置了一个主题的订阅。然后我每小时用Cloud Scheduler触发一次Cloud功能。

1. 如果我需要使用pull，有更好的方法吗

我从文档中复制了一个示例，但它引发了一个错误。

TypeError: match error: could not instantiate a path template from 
projects/projectname/subscriptions/projects/projectname/subscriptions/test at PathTemplate.match 
(/srv/node_modules/google-gax/build/src/pathTemplate.js:82:19) at PathTemplate.render 
(/srv/node_modules/google-gax/build/src/pathTemplate.js:118:14) at SubscriberClient.subscriptionPath 
(/srv/node_modules/@google-cloud/pubsub/build/src/v1/subscriber_client.js:1838:57) at 
exports.helloPubSub (/srv/index.js:22:45) at /worker/worker.js:825:24 at <anonymous> at 
process._tickDomainCallback (internal/process/next_tick.js:229:7)

2. 导致错误的原因是什么

我复制的代码如下所示：

const pubsub = require('@google-cloud/pubsub');
const subClient = new pubsub.v1.SubscriberClient();
const subscriptionName = 'name_of_my_subscription';
const projectId = 'my_project_id';
const timeout = 60;

exports.helloPubSub = async (event, context) => {
const formattedSubscription = subClient.subscriptionPath(projectId, subscriptionName);
const request = {
subscription: formattedSubscription,
maxMessages: 10,
};
const [response] = await subClient.pull(request);
const ackIds = [];
for (const message of response.receivedMessages) {
console.log(`Received message: ${message.message.data}`);
ackIds.push(message.ackId);
}
const ackRequest = {
subscription: formattedSubscription,
ackIds: ackIds,
};
await subClient.acknowledge(ackRequest);
};

谢谢！

Answer 1

这一行出现错误消息：

const formattedSubscription = subClient.subscriptionPath(projectId, subscriptionName);

因为您的"name_of_my_subscription"是projects/your-project/subscriptions/subname而不是subname:

const subscriptionName = 'name_of_my_subscription'; 

这就是为什么你会得到双重名称projects/projectname/subscriptions/:

could not instantiate a path template from 
projects/projectname/subscriptions/projects/projectname/subscriptions/test