在链式Promisified函数中创buildMongoDB文档
应用程序每15分钟运行一个进程，以下列格式创build许多输出文件：
<timestamp>-<piece-code>.txt 由进程创build的所有文件将共享“时间戳”组件，但“片段代码”将有所不同，这意味着我有一个时间戳到多个片断的关系，我想保存在mongodb为：
"Registry" { time: (numeric) } "Piece" { file: (string), piece: (string), registry: (reference) }
在这个过程中，我想查找是否已经创build一个时间戳 ，以避免重复，但我的代码似乎无法做到这一点。
在此先感谢您的帮助！
const mongoose = require('mongoose'); const Registry = require('../model/Registry'); const Piece = require('../model/Piece'); mongoose.Promise = require('bluebird'); // Set up default mongoose connection let mongoDB = 'mongodb://127.0.0.1/numbers'; mongoose.connect(mongoDB, { useMongoClient: true }); //Get the default connection let db = mongoose.connection; // Bind connection to error event db.on('error', console.error.bind(console, 'MongoDB connection error:')); // Error handler let error = (err) => { console.log("** Error: ", err); db.close(); }; // Finish routine let finish = () => { console.log("I have finished"); db.close(); }; // Create a number if it does not exist already let newRegistry = (timestamp) => { return new Promise((resolve, reject) => { Registry.count({}).then((c) => { console.log(c) }) // Does this Registry exist? Registry.findOne({ time: timestamp }) .then((reg, err) => { if (err) { reject(err); } // Create when it does not exist if (!reg) { Registry.create({ time: timestamp }).then((doc, err) => { if (err) { reject(err); } resolve(doc._id); }) .catch(error); } else { // Else, resolve resolve(reg._id); } }); }); } let newPiece = (registryId, filename, piece) => { return Piece.create({ registry: mongoose.Types.ObjectId(registryId), file: filename, piece: piece }); }; let createRegs = (files) => { return new Promise((resolve, reject) => { let promises = []; let total = files.length; for (let i=0; i<total; i++) { let fileAr = files[i].split("-"); let time = fileAr[0]; let piece = fileAr[1]; let promise = newRegistry(time) .then((regId) => { return newPiece(regId, files[i], piece); }); promises.push(promise); } Promise.all(promises) .then(() => { resolve(); }) .catch(error); }); } // Register input time and file pieces: one "time" can have many "pieces" let filenames = ["1512473256-e.txt", "1512471758-a.txt", "1512471892-a.txt", "1512471758-b.txt"]; // Must end up with 3 "Registry" and 4 "Piece" documents createRegs(filenames) .then(finish) .catch(error);
也许值得摆脱你的数组中的重复数字？ 通过做这样的事情：
let filtered = []; numbers.forEach((num) => { // in case we don't have such entity creating it if (!filtered.includes(num)) { filtered.push(num); } // in case we have just returning resolved promise return Promise.resolve(); });
然后在DB中创build你的实体：
const promises = filtered.map(n => { Number.findOne({ number: n }) .then(result => if(!result) { return Number.create({ number: n }); }).catch(err => console.log(err)); }); Promise.all(promise).then(() => /* Doing what you want to do after saving */)
我的做法是这样的：
- 首先，我会创build一个字典，其中键将是时间戳，值将是一个不同的片段的数组。
- 一旦你有这个字典，我会对待每个时间戳列表
- 在数据库中查找时间戳。 创build它，如果它不存在。
- 循环遍历所有时间戳，并将其添加到数据库中。
采用这种方法可以避免并发问题。 希望能帮助到你。