Question

问题是api请求中的数据在数据库中的字段应显示为“ 0个字段”。我认为这是因为mongo在api响应位于对象变量之前将对象插入数据库。所以我认为我需要让数据库插入功能等待api请求完成。

有人知道我该怎么做吗？

const express = require('express');
const bodyParser = require('body-parser');
const exphbs = require('express-handlebars');
const path = require('path');
const fs = require('fs');
const fetch = require('node-fetch');

var mongodb = require('mongodb')
var mongoDbQueue = require('mongodb-queue')

const url = 'mongodb://localhost:27017/'
const client = new mongodb.MongoClient(url, { useNewUrlParser: true })

const app = express();


// View engine setup
app.engine('handlebars', exphbs());
app.set('view engine', 'handlebars');
app.set('views', __dirname);

// Static folder
app.use('/public', express.static(path.join(__dirname, 'public')));

// Body Parser Middleware
app.use(bodyParser.urlencoded({ extended: false }));
app.use(bodyParser.json());

app.get('/', (req, res) => {
  res.render('main');
});

app.post('/send', (req, res) => {
  var item = {
  name: req.body.name,
  age: req.body.age,
country: req.body.country,
  isValid:
 fetch(*/normaly working url inside here*/)  
      .then(res => res.json())
      .then(data => isValid = data)
      .then(() => console.log(isValid))

}



client.connect(err => {
    const db = client.db('test')
    const queue = mongoDbQueue(db, 'my-queue')


  queue.add(item, (err, id) => {
 
  })

  })



});



app.listen(3000, () => console.log('Server started...'));

.then(() => console.log(equivalent))为我提供了正确的值，因此与api无关

Answer 1

问题出在提取API的异步特性上。直到稍后的某个时间点，isValid中的值才被解析。另外，您使用的值有误。

下面的代码等待响应，设置值，并在正确的范围内更新数据库。

app.post('/send', (req, res) => {
 fetch(*/normaly working url inside here*/)  
      .then(res => res.json())
      .then(isValid => {
       var item = {
        name: req.body.name,
        age: req.body.age,
        country: req.body.country,
        isValid //same as isValid : isValid
      }
      client.connect(err => {
       if(!err) { // error check
         const db = client.db('test');
         const queue = mongoDbQueue(db, 'my-queue');
         queue.add(item, (err, id) => {})
       }
      });
    });
});

Answer 2

目前尚不清楚您要达到的目标，但我的猜测是，您希望在提取时添加数据库条目 Promise已在/ send路线上完成。在这种情况下，您需要像这样重构代码：

const express = require('express');
const bodyParser = require('body-parser');
const exphbs = require('express-handlebars');
const path = require('path');
const fs = require('fs');
const fetch = require('node-fetch');

var mongodb = require('mongodb')
var mongoDbQueue = require('mongodb-queue')

const url = 'mongodb://localhost:27017/'
const client = new mongodb.MongoClient(url, { useNewUrlParser: true })

const app = express();

// View engine setup
app.engine('handlebars', exphbs());
app.set('view engine', 'handlebars');
app.set('views', __dirname);

// Static folder
app.use('/public', express.static(path.join(__dirname, 'public')));

// Body Parser Middleware
app.use(bodyParser.urlencoded({ extended: false }));
app.use(bodyParser.json());

app.get('/', (req, res) => {
    res.render('main');
});

app.post('/send', (req, res) => {
    let name = req.body.name;
    let age = req.body.age;
    let country = req.body.country;
    fetch( /* normaly working url inside here */)
        .then(res => res.json())
        .then(data => {
            let item = { name, age, country, isValid: true };
            // data is ready to be used or added to the database at this point:
            client.connect(err => {
                const db = client.db('test')
                const queue = mongoDbQueue(db, 'my-queue')
                queue.add(item, (err, id) => {
                })
            })

        })
        .catch((error) => console.log(error));

});

app.listen(3000, () => console.log('Server started...'));

无法将从api获取的变量添加到数据库

2 个答案: