javascript - 创建一个 javascript 对象并绑定(bind)它

Question

我正在尝试构建我的第一个 Node 应用程序。我的 app.js 文件如下所示。我想通过执行“app = require('app')”从另一个模块访问它。然后我想访问 app.app、app.dbConn 和 app.models

问题是，当我需要此模块时，结果对象上不存在 app.models。

var express = require('express');
var path = require('path');
var orm = require('orm');

var settings = require('./config/settings');
var mainRouter = require('./config/routes');
var environment = require('./config/environment');
var db = require('./config/db');
var auth = require('./modules/auth');

module.exports = new function(){
    this.app = express();

    // middlewares must be added in order - start with the basics
    environment(this.app);
    if (process.env.TESTING) { dbSettings = settings.dbTesting; }
    else { dbSettings = settings.db; }

    // add models to the request early in the middleware chain
    this.dbConn = orm.connect(dbSettings, function(err){
      if (err) return console.error('DB Connection error: ' + err);
      else{
        this.models = db.init(this.dbConn);
        this.app.use(function(req,res,next){
          req.models = this.models;
          next();
        });

        passport = auth.init(this.models);
        authRouter = auth.router(passport)

        this.app.use('/users', authRouter);
        this.app.use(mainRouter);
      }
    }.bind(this));
    this.app.listen(settings.port);
    console.log('Server started... listening on port ' + settings.port)
}

实现我想要的唯一方法是使用一个带有回调的函数，最后我这样重写了我的代码:

var express = require('express');
var path = require('path');
var orm = require('orm');

var settings = require('./config/settings');
var mainRouter = require('./config/routes');
var environment = require('./config/environment');
var db = require('./config/db');
var auth = require('./modules/auth');

var app;

module.exports = function(cb){
  app = express();

  // middlewares must be added in order - start with the basics
  environment(app);
  if (process.env.TESTING) { dbSettings = settings.dbTesting; }
  else { dbSettings = settings.db; }

  // add models to the request early in the middleware chain
  dbConn = orm.connect(dbSettings, function(err){
    if (err) return console.error('DB Connection error: ' + err);
    else{
      models = db.init(dbConn);
      app.use(function(req,res,next){
        req.models = models;
        next();
      });

      passport = auth.init(this.models);
      authRouter = auth.router(passport)

      app.use('/users', authRouter);
      app.use(mainRouter);

      cb({
        dbConn: dbConn,
        app: app,
        models: models
      });
    }
  });
}

if (!process.env.TESTING) {
  module.exports(function(server){
    server.app.listen(settings.port);
    console.log('Server started... listening on port ' + settings.port)
  });
}

Answer 1

app.models 仅在数据库连接完成后定义:您不能在需要模块后立即使用它。您应该提供一个入口点，该入口点接受连接准备好后要调用的函数，并在 orm.connect 回调中调用该函数。

即使是“服务器已启动”消息也有点误导，因为它在服务器实际上可以执行任何操作之前显示，因为传递给 orm.connect 的函数尚未被调用。