mvc-3模型和数据(1)

MVC和命名空间

var User = function(atts) {
  this.attribute = atts || {};
}
//和具体user相关的方法
User.prototype.destroy = function() {};
//和具体user不相关的函数和变量
User.fetchRemove = function() {};
var user = new User({name:'jinks'});
user.destroy();

构建对象关系映射

如：

• 任何model的改变会向后台发起一个ajax请求
• model和view绑定，当一个实例改变时，马上从view中反映出来

原型继承

• 这里用到Object.create,对于没有的浏览器，可以模拟方法

if(typeof Object.create !== "function") {
  Object.create = function(o) {
    function F(){};
    F.prototype = o;
    return new F();
  }
}

var Model = {
  inherited: function() {},
  created: function() {},
  prototype: {
    init: function() {}
  },
  create: function() {
    var object = Object.create(this);
    object.parent = this;
    object.prototype = object.fn = Object.create(this.prototype);
    object.created();
    this.inherited(object);
    return object;
  },
  init: function() {
    var instance = Object.create(this.prototype);
    instance.parent = this;
    instance.init.apply(instance, arguments);
    return instance;
  }
}
var Asset = Model.create();
var User = Model.create();
var user = User.init();

添加ORM属性

var Model = {
  /*代码片段*/
  extend: function(o) {
    var extended = o.extended;
    for(var i in o) {
      this[i] = o[i];
    }
    if(extended) extended(this);
  },
  include: function(o) {
    var included = o.included;
    for(var i in o) {
      this.prototype[i] = o[i];
    }
    if(included) included(this);
  }
}
//添加到Model对象属性
Model.extend({
  find: function() {}
});
//添加Model.prototype中，所有实例共享这一属性
Model.include({
  load: function(atts) {
    for(var i in atts) {
      this[i] = atts[i];
    }
  },
  init: function(atts) {
    if(atts) this.load(atts);
  }
});

var Asset = Model.create();
var asset = Asset.init({name: "a.png"});

持久化记录

将引用保存至新创建的实例中以便任何时候都可以访问

var Model = {
	/*代码*/
}
//用来保存资源的对象
Model.records = {};
Model.include({
  newRecord: true,
  create: function() {
    this.newRecord = false;
    this.parent.records[this.id] = this;
  },
  destroy: function() {
    delete this.parent.records[this.id];
  }
});
//更新一个已经存在的实例
Model.include({
  update: function() {
    this.parent.records[this.id] = this;
  }
});
//添加一个快捷函数来保持实例
Model.include({
  save: function() {
    this.newRecord ? this.create() : this.update();
  }
});
Model.extend({
  //通过id查找，找不到抛出异常
  find: function(id) {
    var id = this.records[id];
    if(id) {
      return id;
    } else {
      throw new Error("Unknow record");
    }
  }
});

var Asset = Model.create();
var asset = Asset.init();
asset.name = "same, same";
asset.id = 1;
asset.save();

var asset2 = Asset.init();
asset2.name = "but different";
asset2.id = 2;
asset2.save();

console.log(Asset.records);
asset2.destroy();
console.log(Asset.records);

增加ID支持

使用全局统一标识(GUID)生成器来自动生成ID

//使用Math.random()来产生一个伪随机数的GUID
Math.guid = function(){
  return 'xxxxxxxx-xxxx-4xxx-yxxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function(c){
      var r = Math.random() * 16 | 0,
        v = c === 'x' ? r : (r & 0x3 | 0x8);
        return v.toString(16)
    }).toUpperCase();
};
//修改create()函数
Model.include({
  create: function() {
    if(!this.id) this.id = Math.guid();
    this.newRecord = false;
    this.parent.records[this.id] = this;
  }
});

var Asset = Model.create();
var asset = Asset.init();
asset.save();
console.log(asset.id);