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);