处理Node.js异步返回"require"(节点ORM)

Question

我正在使用Node.js ORM模块:https://github.com/dresende/node-orm

我可以通过这样做来创建一个模型:

    var orm = require("orm");
    var db = orm.connect("creds", function (success, db) {
        if (!success) {
            console.log("Could not connect to database!");
            return;
        }

      var Person = db.define("person", {
        "name"   : { "type": "string" },
        "surname": { "type": "string", "default": "" },
        "age"    : { "type": "int" }
      });
    });

问题是我想将Person(以及所有其他模型)放在外部包含中.

如果我做这样的事情:

   require("./models/person.js");

我不能在其中使用db变量,因为它只存在于orm.connect()的回调函数的上下文中.我无法移动orm.connect到require(person.js)并为模型信息执行module.export,因为在父脚本中,将发生require,然后下一行不会准备好模型因为它没有等待回调.IE

//person.js
// db and orm get defined up here as before
Person = {}; // code from above, with the define and etc. 
Module.exports = Person;
//app.js 
person = require("./models/person.js");
console.log(person); // returns undefined, connect callback isn't done yet 

我觉得有一种明显的方法可以做到这一点.

Answer 1

也许可以让person.js导出成一个函数,并传入db？像这样:

//app.js
var orm = require("orm");
var db = orm.connect("creds", function (success, db) {
    if (!success) {
        console.log("Could not connect to database!");
        return;
    }

  var Person = require("./models/person.js")(db);
});

//person.js
module.exports = function(db){
    return db.define("person", {
        "name"   : { "type": "string" },
        "surname": { "type": "string", "default": "" },
        "age"    : { "type": "int" }
    });
}