google-actions-如何在nodejs中的Promise中使用mongo-on-google库在对话框流实现中进行mongodb查询？

Question

In my dialogflow fulfillment, I want to query a mongodb database and based on the result return an answer. Since I use the actions-on-google database, I must use promises for async calls. How can I do that for a mongodb query?

 const express = require("express"); const bodyParser = require("body-parser"); const {dialogflow} = require('actions-on-google'); const app = dialogflow() var MongoClient = require('mongodb').MongoClient; var url = "mongodb://localhost:27017/" app.intent('Mongodb', (conv) =>{ MongoClient.connect(url, function(err, db) { if (err) throw err; var dbo = db.db("mydb"); var query = { address: /^S/ }; var path; db.collection('paths', function(err, collection) { collection.find({}).toArray(function(err, results) { path = results; console.log(results); }); }); }); conv.ask(path) }); 

Answer 1

The Node mongodb package will return a Promise from most (maybe all?) of its callback-based APIs if you don't pass a callback function. For example, you can call db.collection('paths').then(function (collection) { … }) . You can then chain the promises like the following:

return MongoClient.connect(url)
  .then(function (client) {
    return client.db('mydb');
  }).then(function (db) {
    return db.collection('paths');
  }).then(function (collection) {
    return collection.find({}).toArray();
  }).then(function (path) {
    conv.ask(path);
  });

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You can also use the new Promise((resolve, reject) => …) constructor to wrap anything that is callback based in a Promise API. The Promise documentation on MDN has a good example here .