如何在Node Express应用程序中传递对象？

Question

我正在使用express和node-postgres（https://github.com/brianc/node-postgres）构建一个基于Node的应用程序。我只想建立一次数据库客户端连接，并且希望能够从不同的模块访问此数据库连接。最好的方法是什么？我试图只导出db连接，而不是整个express应用程序。实质上，如何在Node应用程序中导出和访问对象是最好的方式？

我查看了这个类似的问题，但它似乎只适用于mongoose。 最佳方法与mongoose / node.js共享数据库连接参数

- user2253099

Answer 1

并不存在所谓的“最佳方式”。如果您需要在不同模块之间使用相同的对象，则必须将其包装在一个模块中。可以像这样实现：

//db.js
var postgres = require (...)
var connection;

module.exports = {
  getConnection: function (){
    return connection;
  },
  createConnection: function (){
    connection = createConnection (postgress);
  }
};

//app.js - main file
require ("./db").createConnection ();

//a.js
var db = require("./db")
db.getConnection()

//b.js
var db = require("./db")
db.getConnection()

- Gabriel Llamas

Answer 2

嗨，我正在解决这个问题，它来自RefLink。

您可以创建这样的方案来映射您的数据

    const User = mongoose.model('Story', userSchema);
    module.exports = User;
    const mongoose = require('mongoose');
    let Schema = mongoose.Schema;
    const userSchema = new Schema({
    UserID: {
        type: mongoose.Schema.Types.Mixed,
    },
    User_Info: {
        First_Name: {
        type: String,
        },
        Last_Name: {
        type: String,
        },
        Current_Address: {
        type: String,
        },
        Email_Address: {
        type: String,
        },
    },
        Phone_Numbers: [{
            Home_Phone: {
            type: Number,
            },
            Work_Phone: {
            type: Number,
            },
            Cell_Phone: {
            type: Number,
            },
                Phone_verified: [{
                Home: Boolean,
                Work: Boolean,
                Cell: Boolean,
                }],
        }],
    })
    const User = mongoose.model('User', userSchema);
    module.exports = User;

而 API 路由可能看起来像这样

        app.post('/api/user', function(req, res) {
    User.create({
        UserID: req.body.userid,
        User_Info: req.body.userinfo,
        First_Name: req.body.firstname,
        Last_Name: req.body.lastname,
        Current_Address: req.body.currentaddress,
        Email_Address: req.body.emailaddress,
        Phone_Numbers: req.body.phonenumbers,
        Home_Phone: req.body.homephone,
        Work_Phone: req.body.workphone,
        Cell_Phone: req.body.cellphone,
        Phone_Verified:
        req.body.phoneverified,
        Home: req.body.home,
        Work: req.body.work,
        Cell: req.body.cell,
    }).then(user => {
        res.json(user)
    });
    });

- Cesar Vega

Answer 3

你可以这样做...

//db.js
var pg = require('pg'); 

var conString = "tcp://postgres:1234@localhost/postgres";

module.exports.connectDatabase = function(callback){
var client = new pg.Client(conString);
client.connect(function(err) {
  if(err){
     console.log(err);
     process.exit(1);
  }

  module.exports.client = client;
  callback();
})

//app.js
// We are trying to connect to database at the start of our app and if it fails we exit       the process
var db = require('./db');
db.connectDatabase(function(){
  // your other code
})

//a.js
var db = require('./db');
//you can access your client here to perform database operations like that
db.client

- khurrum qureshi