Firebase云功能中的嵌套HTTP请求 [英] Nested HTTP requests in Firebase cloud function
问题描述
我正在使用HTTP触发的Firebase云功能来发出HTTP请求.我返回了一系列结果(Meetup.com的事件)，并将每个结果推送到Firebase实时数据库.但是对于每个结果，我还需要对另一个信息(承载事件的组的类别)发出另一个HTTP请求，以将其折叠到我要为该事件推送到数据库的数据中.这些嵌套的请求导致云功能崩溃，并出现我无法理解的错误.
I'm using an HTTP-triggered Firebase cloud function to make an HTTP request. I get back an array of results (events from Meetup.com), and I push each result to the Firebase realtime database. But for each result, I also need to make another HTTP request for one additional piece of information (the category of the group hosting the event) to fold into the data I'm pushing to the database for that event. Those nested requests cause the cloud function to crash with an error that I can't make sense of.
const functions = require("firebase-functions");
const admin = require("firebase-admin");
admin.initializeApp();
const request = require('request');
exports.foo = functions.https.onRequest(
(req, res) => {
var ref = admin.database().ref("/foo");
var options = {
url: "https://api.meetup.com/2/open_events?sign=true&photo-host=public&lat=39.747988&lon=-104.994945&page=20&key=****",
json: true
};
return request(
options,
(error, response, body) => {
if (error) {
console.log(JSON.stringify(error));
return res.status(500).end();
}
if ("results" in body) {
for (var i = 0; i < body.results.length; i++) {
var result = body.results[i];
if ("name" in result &&
"description" in result &&
"group" in result &&
"urlname" in result.group
) {
var groupOptions = {
url: "https://api.meetup.com/" + result.group.urlname + "?sign=true&photo-host=public&key=****",
json: true
};
var categoryResult = request(
groupOptions,
(groupError, groupResponse, groupBody) => {
if (groupError) {
console.log(JSON.stringify(error));
return null;
}
if ("category" in groupBody &&
"name" in groupBody.category
) {
return groupBody.category.name;
}
return null;
}
);
if (categoryResult) {
var event = {
name: result.name,
description: result.description,
category: categoryResult
};
ref.push(event);
}
}
}
return res.status(200).send("processed events");
} else {
return res.status(500).end();
}
}
);
}
);
函数崩溃，日志显示:
Error: Reference.push failed: first argument contains a function in property 'foo.category.domain._events.error' with contents = function (err) {
if (functionExecutionFinished) {
logDebug('Ignoring exception from a finished function');
} else {
functionExecutionFinished = true;
logAndSendError(err, res);
}
}
at validateFirebaseData (/user_code/node_modules/firebase-admin/node_modules/@firebase/database/dist/index.node.cjs.js:1436:15)
at /user_code/node_modules/firebase-admin/node_modules/@firebase/database/dist/index.node.cjs.js:1479:13
at Object.forEach (/user_code/node_modules/firebase-admin/node_modules/@firebase/util/dist/index.node.cjs.js:837:13)
at validateFirebaseData (/user_code/node_modules/firebase-admin/node_modules/@firebase/database/dist/index.node.cjs.js:1462:14)
at /user_code/node_modules/firebase-admin/node_modules/@firebase/database/dist/index.node.cjs.js:1479:13
at Object.forEach (/user_code/node_modules/firebase-admin/node_modules/@firebase/util/dist/index.node.cjs.js:837:13)
at validateFirebaseData (/user_code/node_modules/firebase-admin/node_modules/@firebase/database/dist/index.node.cjs.js:1462:14)
at /user_code/node_modules/firebase-admin/node_modules/@firebase/database/dist/index.node.cjs.js:1479:13
at Object.forEach (/user_code/node_modules/firebase-admin/node_modules/@firebase/util/dist/index.node.cjs.js:837:13)
at validateFirebaseData (/user_code/node_modules/firebase-admin/node_modules/@firebase/database/dist/index.node.cjs.js:1462:14)
如果我省略了获取组类别的内容，则其余代码工作正常(只需将每个事件的名称和描述写入数据库，没有嵌套请求).那么正确的方法是什么?
If I leave out the bit for getting the group category, the rest of the code works fine (just writing the name and description for each event to the database, no nested requests). So what's the right way to do this?
推荐答案
我怀疑此问题是由于回调引起的.当您使用Firebase函数时，导出的函数应等待所有内容执行，或者返回一个在所有内容完成执行后便会解决的承诺.在这种情况下，导出的函数将在其余执行完成之前返回.
I suspect this issue is due to the callbacks. When you use firebase functions, the exported function should wait on everything to execute or return a promise that resolves once everything completes executing. In this case, the exported function will return before the rest of the execution completes.
这是更多基于承诺的东西的开始-
Here's a start of something more promise based -
const functions = require("firebase-functions");
const admin = require("firebase-admin");
admin.initializeApp();
const request = require("request-promise-native");
exports.foo = functions.https.onRequest(async (req, res) => {
const ref = admin.database().ref("/foo");
try {
const reqEventOptions = {
url:
"https://api.meetup.com/2/open_events?sign=true&photo-host=public&lat=39.747988&lon=-104.994945&page=20&key=xxxxxx",
json: true
};
const bodyEventRequest = await request(reqEventOptions);
if (!bodyEventRequest.results) {
return res.status(200).end();
}
await Promise.all(
bodyEventRequest.results.map(async result => {
if (
result.name &&
result.description &&
result.group &&
result.group.urlname
) {
const event = {
name: result.name,
description: result.description
};
// get group information
const groupOptions = {
url:
"https://api.meetup.com/" +
result.group.urlname +
"?sign=true&photo-host=public&key=xxxxxx",
json: true
};
const categoryResultResponse = await request(groupOptions);
if (
categoryResultResponse.category &&
categoryResultResponse.category.name
) {
event.category = categoryResultResponse.category.name;
}
// save to the databse
return ref.push(event);
}
})
);
return res.status(200).send("processed events");
} catch (error) {
console.error(error.message);
}
});
有关更改的快速概述-
- 使用await和async调用来等待事情完成，而不是在回调中被触发(与.pron函数相比，async和await通常比promise更容易阅读，因为执行顺序是代码的顺序)
- 使用了支持promise/await的request-promise-native(即await表示等待，直到promise返回，所以我们需要一些返回promise的东西)
- 使用const并让vs. var作为变量；这扩大了变量的范围
- 与其进行诸如if(is good)的检查{做美好的事情}，而是使用if(isbad){返回一些错误}做精瘦的事情.这使代码更易于阅读，并防止了许多嵌套的ifs而不知道它们的结尾
- 使用Promise.all()，以便同时检索每个事件的类别
这篇关于Firebase云功能中的嵌套HTTP请求的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
