我为Firebase Cloud Functions开发。我有一个像这样的Firebase实时数据库：
----- myData
-------eqewrwrepere (this one is a device token)
---------Lta+sde-fer (this one is a firebase id)
firstvalue : "a"
secondvalue : "b"
----------Qrgd+ad-qdda (this one is second firebase id)
firstvalue : "c"
secondvalue : "d"
-------eqwerSAsdqe (this one is another device token)
---------Lta+sde-fer (this one is a firebase id)
firstvalue : "x"
secondvalue : "y"
----------Qrgd+ad-qdda (this one is second firebase id)
firstvalue : "z"
secondvalue : "t"
我通过这段代码获取这些数据。通过此代码，我获取了所有数据并将它们放入数组。当获取完成时，我循环使用此数组查找项目。我是iOS开发人员，所以我是NodeJS的新手。这是我想做的：
firstvalue。现在，我能够检索阵列中的数据库项目。当我在for循环中发出请求时，该请求称为异步。因此for循环继续进行，但是请求响应或写入文件和视觉处理仅执行一次。
在for循环中，获取databasearray [0]，发出请求，写入文件，使用视觉api处理它，更新数据库并转到下一个databasearray [1]项目。
我在不同页面上读到了Promises。但是我不明白。
谢谢。
'use strict';
const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp(functions.config().firebase);
var request = require('request');
var fs = require('fs');
//var fs = require("fs");
// Get a reference to the Cloud Vision API component
const Vision = require('@google-cloud/vision');
const vision = new Vision.ImageAnnotatorClient();
// Imports the Google Cloud client library
//const {Storage} = require('@google-cloud/storage');
var fs = require("fs");
var os = require("os");
var databaseArray = [];
exports.hourly_job = functions.pubsub
.topic('hourly-job')
.onPublish((event) => {
console.log("Hourly Job");
var db = admin.database();
var ref = db.ref("myData")
ref.once("value").then(function(allData) {
allData.forEach(function(deviceToken) {
deviceToken.forEach(function(firebaseIDs) {
var deviceTokenVar = deviceToken.key;
var firebaseIDVar = firebaseIDs.key;
var firstvalue = firebaseIDs.child("firstvalue").val();
var secondvalue = firebaseIDs.child("secondvalue").val();
var items = [deviceTokenVar, firebaseIDVar, firstvalue, secondvalue];
databaseArray.push([...items]);
});
});
return databaseArray;
}).then(function(databasem) {
var i;
for (i = 0; i < databaseArray.length; i++) {
var databaseArrayDeviceToken = databaseArray[i][0];
console.log("DeviceToken: " + databaseArrayDeviceToken);
var databaseArrayFirebaseID = databaseArray[i][1];
console.log("FirebaseID: " + databaseArrayFirebaseID);
var databaseArrayfirstvalue = databaseArray[i][2];
console.log("firstval: " + databaseArrayfirstvalue);
var databaseArraysecondval = databaseArray[i][3];
console.log("Second: " + databaseArraysecondval);
var url = "http://api.blabla" + databaseArrayfirstvalue;
/////////////here make a request, pause loop, process returned image, but how //////////////////////
request.get({
url: url,
encoding: 'binary'
}, function(error, httpResponse, body) {
if (!error && httpResponse.statusCode == 200) {
fs.writeFileSync('/tmp/processed.jpg', body, 'binary')
console.log("file written");
})
}
});
return true;
});
答案 0 :(得分：1)
我发现Mocas帮助解决方案。这是解决方案。我在代码中使用异步/等待功能。现在for循环等待函数响应。但是现在我有不同的问题。我认为主要的异步功能由于等待而挂起。然后下一个小时触发，它将再次运行。因此控制台日志会在for循环中显示15-16-17或更多的“ i”值。我在数据库阵列中有4个元素，但控制台日志每小时显示的次数更多。而且每次都增加。所以我想我应该在超时后取消此等待功能。但是我不知道如何。这是代码：
use strict';
const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp(functions.config().firebase);
var request = require('request-promise').defaults({ encoding: null });
var fs = require('fs');
// Get a reference to the Cloud Vision API component
const Vision = require('@google-cloud/vision');
const vision = new Vision.ImageAnnotatorClient();
var os = require("os");
var databaseArray = [];
var uniqueFilename = require('unique-filename')
exports.hourly_job = functions.pubsub
.topic('hourly-job')
.onPublish((event) => {
console.log("Hourly Job");
var db = admin.database();
var ref = db.ref("myData")
ref.once("value").then(function(allData) {
allData.forEach(function(deviceToken) {
deviceToken.forEach(function(firebaseIDs) {
var deviceTokenVar = deviceToken.key;
var firebaseIDVar = firebaseIDs.key;
var firstvalue = firebaseIDs.child("firstvalue").val();
var secondvalue = firebaseIDs.child("secondvalue").val();
var items = [deviceTokenVar, firebaseIDVar, firstvalue, secondvalue];
databaseArray.push([...items]);
//console.log(databaseArray);
//return true;
});
//return true;
});
return databaseArray;
}).then(function (databasem) {
main().catch(console.error);
});
return true;
});
const main = async () => {
var i;
for (i = 0; i < databaseArray.length; i++) {
console.log("Database Arrays " + i + ". elements: ");
var databaseArrayDeviceToken = databaseArray[i][0];
console.log("DeviceToken: " + databaseArrayDeviceToken);
var databaseArrayFirebaseID = databaseArray[i][1];
console.log("FirebaseID: " + databaseArrayFirebaseID);
var databaseArrayfirst = databaseArray[i][2];
console.log("first: " + databaseArrayfirst);
var databaseArraysecond = databaseArray[i][3];
console.log("second: " + databaseArraysecond);
if (databaseArrayfirst != "") {
var apiUrl = "http://api.blabla;
try {
const apiBody = await request.get(apiUrl);
///////////////////////////vison start//////////////////////
const visionResponseBody = await vision.documentTextDetection(apiBody)
var visionResponse = visionResponseBody[0].textAnnotations[0].description;
console.log("Vision response text " + visionResponse );
...some logic here about response...
/////////////////////////////////////////////////
var getdatabasevar = await admin.database().ref("myData/" + databaseArrayDeviceToken + "/" + databaseArrayFirebaseID);
await getdatabasevar.update({
"firstvalue": visionResponse
});
/////////////////////////////////////////////////
var getanotgerdatabasevar = await admin.database().ref("myData/" + databaseArrayDeviceToken + "/" + databaseArrayFirebaseID + "/" + "secondvalue");
await getanotgerdatabasevar.once("value")
.then(function(var) {
..some logic..
//send notification
});
} catch (error) {
console.error(error);
}
///////////////////////////vison end//////////////////////
}
};
return true;
};