node.js - 当 mongodb 发生变化时更新客户端中的位置

Question

我正在制作一个 Android 应用程序并使用 Express 作为后端。这是我的送货员架构:

var DeliveryBoySchema = new Schema({

    name: String,
    college: {type:String},
    password: {type: String, required: true, select: false},
    lat:{type: String},
    long:{type:String}

});

当送货员改变位置时，它会在 mongodb 中更新。因此，正在查看该送货员的用户(即客户)正在跟踪他的位置。我找到了两种方法来做到这一点:

1。客户端每5秒调用一次api并获取送货员的当前位置。

2。我发现了另一种有趣的方法来做到这一点，即使用套接字。

我不太清楚它的功能。当数据库发生更改并且用户看到当前位置时，我遇到如何更新客户端的问题。

Answer 1

根据 OP 的要求，仅使用 mongoose、nodeJS 和 socket 进行一些编码。实际实现不必完全相同，但以下内容应该给出如何继续进行并填补缺失空白的总体思路。为了方便起见，我将使用 ES6 功能。

nodeJS版本4.2.2，socket.io 1.3.5，mongoose版本4.1.2，express 4.13.3

1. 创建套接字 - 服务器端

//the following is probably your app.js
import express from 'express'
...
var app = express();
var server = http.createServer(app);
...

var socketio = require('socket.io')(server, {
  path: '/socket.io-path, //modify this as per your needs
});
//now register created socket object
require('./components/socket')(socketio);

...
//start the server

//the following is components/socket/index.js

function onConnect(socket){
   //register listeners on mongo schema changes
   require('../../models/deliveryBoy.socket').register(socket);
}

module.exports = function(socketio){
  socketio.on('connection', function(socket) {
    socket.address = socket.request.connection.remoteAddress +
      ':' + socket.request.connection.remotePort; 
    //address, e.g. 127.0.0.1:52243

    socket.connectedAt = new Date();
    socket.log = function(...data) {
      console.log(`SocketIO ${socket.address}`, ...data);
    };
    // Call onDisconnect.
    socket.on('disconnect', function() {
      socket.log('Disconnected: ');
      //do something when user disconnects
    });

    // Call onConnect.
    onConnect(socket);
    socket.log('New connection: ');
  });
};

在 mongoose 架构定义上附加一个钩子(Hook)

//this is to be stored at ./models/deliveryBoy.model 

'use strict';

var mongoose = require('bluebird').promisifyAll(require('mongoose'));
var Schema = mongoose.Schema;

var DeliveryBoySchema = new Schema({
    name: String,
    college: {type:String},
    password: {type: String, required: true, select: false},
    lat:{type: String},
    long:{type:String}
});

//attach a hook to be triggered every time you modify the document
//has to be inserted before the mongoose model is created !!!
//with !!!ATTENTION!!! update method using $set
//for example DeliveryBoy.update({_id:'blah'}, {$set: {long: 1, lat: 0}});
DeliveryBoySchema.post('update', function(){
	var update = this._update;
	if (update.$set && (update.$set.lat || update.$set.long)){
		try{
			var updatedObjectId = this._conditions._id; //will serve as a room
            var newLoc = {
              lat: update.$set.lat,
              long: update.$set.long
            }
			//now emit the event using nodejs event emitter

            require('../../components/app.events').emit('updateLoc', {roomId: updatedObjectId, newLoc: newLoc}); 
		}
	}
});

module.exports = mongoose.model('DeliveryBoy', DeliveryBoySchema);

DeliveryBoy 的套接字监听器

//this is the component which implement socket specifically for delivery boy model
//it is called (register method) from general components/socket module

exports.register = function(socket){
  AppEvents.on('updateLoc', function(socket){
    return function(info){
      socket.to(info.roomId).emit('newLocation', info.newLoc);
    }
  });
}

现在您只需根据送货员 ID 从客户端连接到房间，并使用来自客户端的消息并相应地更新您的 View

还有一件事，这就是如何通过 REST API 更新数据库

app.put('/update/:gameId', function(req, res){
    DeliveryBoy.update({_id: req.params.gameId}, {$set: req.body}, function(err){
      res.send(200); //of course this needs to be handled properly, but i am too tired after typing all these
      //you owe me couple beers dude
});
});

P.S 代码有点乱，不过你应该可以做出相应的改进。如果有任何问题请告诉我。但基本概念应该清楚