backbone.Collection源码笔记
Backbone.Collection
backbone的Collection(集合)，用来存储多个model,并且可以多这些model进行数组一样的操作,比如添加,修改,删除,排序,插入,根据索引取值,等等,数组有的方法,他基本上都有
源码注释
<!DOCTYPE html> <html> <head> <meta charset="utf-8"/> <meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=no" /> <title>backbone</title> <style type="text/css"> *{padding:0;margin:0;} .wrap{width:960px; margin: 100px auto; padding: 20px 0;} ul{ list-style: none;} </style> </head> <body> <div class="wrap"> <div id="a1"></div> <div id="a2"></div> <div id="a3"></div> </div> <script src="http://files.cnblogs.com/wtcsy/jquery.js"></script> <script src="http://files.cnblogs.com/wtcsy/underscore.js"></script> <script src="http://files.cnblogs.com/wtcsy/events.js"></script> <script src="http://files.cnblogs.com/wtcsy/model.js"></script> <script> (function(){ // Backbone.Collection // ------------------- var array = []; var slice = array.slice; // If models tend to represent a single row of data, a Backbone Collection is // more analogous to a table full of data ... or a small slice or page of that // table, or a collection of rows that belong together for a particular reason // -- all of the messages in this particular folder, all of the documents // belonging to this particular author, and so on. Collections maintain // indexes of their models, both in order, and for lookup by `id`. // Create a new **Collection**, perhaps to contain a specific type of `model`. // If a `comparator` is specified, the Collection will maintain // its models in sort order, as they're added and removed. var Collection = Backbone.Collection = function(models, options) { options || (options = {}); //默认的model if (options.model) this.model = options.model; if (options.comparator !== void 0) this.comparator = options.comparator; //重置collection里面的的一些属性 this._reset(); this.initialize.apply(this, arguments); //如果传入的models有数据,可以进行设置 if (models) this.reset(models, _.extend({silent: true}, options)); }; // Default options for `Collection#set`. // 设置的参数 添加的参数 add var setOptions = {add: true, remove: true, merge: true}; var addOptions = {add: true, remove: false}; _.extend(Collection.prototype, Backbone.Events, { // The default model for a collection is just a **Backbone.Model**. // This should be overridden in most cases. model: Backbone.Model, // Initialize is an empty function by default. Override it with your own // initialization logic. initialize: function(){}, // The JSON representation of a Collection is an array of the // models' attributes. toJSON: function(options) { return this.map(function(model){ return model.toJSON(options); }); }, // Proxy `Backbone.sync` by default. /* sync: function() { return Backbone.sync.apply(this, arguments); }, */ // **parse** converts a response into a list of models to be added to the // collection. The default implementation is just to pass it through. parse: function(resp, options) { return resp; }, // Add a model, or list of models to the set. add: function(models, options) { //其实就是调用set方法 只有add设置成true remove设置成false merge设置成false return this.set(models, _.extend({merge: false}, options, addOptions)); }, // Update a collection by `set`-ing a new list of models, adding new ones, // removing models that are no longer present, and merging models that // already exist in the collection, as necessary. Similar to **Model#set**, // the core operation for updating the data contained by the collection. set: function(models, options) { options = _.defaults({}, options, setOptions); //parse 必须是一个函数 传入的后将models进行一次转换 if (options.parse) models = this.parse(models, options); var singular = !_.isArray(models); models = singular ? (models ? [models] : []) : models.slice(); var id, model, attrs, existing, sort; var at = options.at; // this.comparator 是排序的东西 如果是函数 sotrAttr为null 否则sotrAttr为true var sortable = this.comparator && (at == null) && options.sort !== false; var sortAttr = _.isString(this.comparator) ? this.comparator : null; var toAdd = [], toRemove = [], modelMap = {}; var add = options.add, merge = options.merge, remove = options.remove; var order = !sortable && add && remove ? [] : false; var targetProto = this.model.prototype; // Turn bare objects into model references, and prevent invalid models // from being added. //对models进行一次遍历 找出要add的 要remove的 for (var i = 0, length = models.length; i < length; i++) { attrs = models[i] || {}; //通过查找model的属性找出id 可以是方便后面用 id可以是model本身 也可以是model的cid 或者是model的id if (this._isModel(attrs)) { id = model = attrs; } else if (targetProto.generateId) { id = targetProto.generateId(attrs); } else { id = attrs[targetProto.idAttribute || Model.prototype.idAttribute]; } // If a duplicate is found, prevent it from being added and // optionally merge it into the existing model. // return this._byId[obj] || this._byId[obj.id] || this._byId[obj.cid]; // 看model是否在this.models里面存在 如果存在,并且设置了remove吧model放到modelMap中 // 如果设置了merge model重新设置他的属性 如果设置了排序 排序标识sotr设置成true,数据改变了 肯定要排序一次的 if (existing = this.get(id)) { if (remove) modelMap[existing.cid] = true; if (merge) { attrs = attrs === model ? model.attributes : attrs; if (options.parse) attrs = existing.parse(attrs, options); existing.set(attrs, options); if (sortable && !sort && existing.hasChanged(sortAttr)) sort = true; } models[i] = existing; // If this is a new, valid model, push it to the `toAdd` list. } else if (add) { // 如果遍历的model不存在 变并且设置了add //对这个model做一些操作_prepareModel 如果传入的attrs是backbone实例化的model则只设置model.collection指向this //如果attrs只是数据 则实例化model并且model.collection指向this // 然后把model放到 toAdd中 方便后面使用 //最后 以model的cid为key 存入this._byId中 model = models[i] = this._prepareModel(attrs, options); if (!model) continue; toAdd.push(model); this._addReference(model, options); } // Do not add multiple models with the same `id`. model = existing || model; if (!model) continue; //order 如果是add或者是remove并且没有设置排序 并且model是新实例化的 添加到order里面去 后面会用到 if (order && (model.isNew() || !modelMap[model.id])) order.push(model); modelMap[model.id] = true; } // Remove nonexistent models if appropriate. if (remove) { // 做删除 先做一些准备 然后添加到toRemove里面去 for (var i = 0, length = this.length; i < length; i++) { if (!modelMap[(model = this.models[i]).cid]) toRemove.push(model); } if (toRemove.length) this.remove(toRemove, options); } // See if sorting is needed, update `length` and splice in new models. if (toAdd.length || (order && order.length)) { //符合添加条件就记性添加 if (sortable) sort = true; this.length += toAdd.length; if (at != null) { for (var i = 0, length = toAdd.length; i < length; i++) { this.models.splice(at + i, 0, toAdd[i]); } } else { if (order) this.models.length = 0; var orderedModels = order || toAdd; for (var i = 0, length = orderedModels.length; i < length; i++) { this.models.push(orderedModels[i]); } } } // Silently sort the collection if appropriate. //符合排序条件 进行排序 if (sort) this.sort({silent: true}); // Unless silenced, it's time to fire all appropriate add/sort events. if (!options.silent) { //如果没有设置silent 触发每个model的add的回调 for (var i = 0, length = toAdd.length; i < length; i++) { (model = toAdd[i]).trigger('add', model, this, options); } if (sort || (order && order.length)) this.trigger('sort', this, options); } // Return the added (or merged) model (or models). return singular ? models[0] : models; }, // Remove a model, or a list of models from the set. remove: function(models, options) { // 删除model 删除this._byId对model的引用 //触发model本身的remove绑定的回调 var singular = !_.isArray(models); models = singular ? [models] : _.clone(models); options || (options = {}); for (var i = 0, length = models.length; i < length; i++) { var model = models[i] = this.get(models[i]); if (!model) continue; delete this._byId[model.id]; delete this._byId[model.cid]; var index = this.indexOf(model); this.models.splice(index, 1); this.length--; if (!options.silent) { options.index = index; model.trigger('remove', model, this, options); } this._removeReference(model, options); } return singular ? models[0] : models; }, // Force the collection to re-sort itself. You don't need to call this under // normal circumstances, as the set will maintain sort order as each item // is added. sort: function(options) { if (!this.comparator) throw new Error('Cannot sort a set without a comparator'); options || (options = {}); // Run sort based on type of `comparator`. if (_.isString(this.comparator) || this.comparator.length === 1) { this.models = this.sortBy(this.comparator, this); } else { this.models.sort(_.bind(this.comparator, this)); } if (options.reverse) this.models = this.models.reverse(); if (!options.silent) this.trigger('sort', this, options); return this; }, // Get a model from the set by id. get: function(obj) { if (obj == null) return void 0; return this._byId[obj] || this._byId[obj.id] || this._byId[obj.cid]; }, // Private method to reset all internal state. Called when the collection // is first initialized or reset. _reset: function() { this.length = 0; this.models = []; this._byId = {}; }, // When you have more items than you want to add or remove individually, // you can reset the entire set with a new list of models, without firing // any granular `add` or `remove` events. Fires `reset` when finished. // Useful for bulk operations and optimizations. reset: function(models, options) { options || (options = {}); for (var i = 0, length = this.models.length; i < length; i++) { this._removeReference(this.models[i], options); } options.previousModels = this.models; this._reset(); models = this.add(models, _.extend({silent: true}, options)); if (!options.silent) this.trigger('reset', this, options); return models; }, // Prepare a hash of attributes (or other model) to be added to this // collection. _prepareModel: function(attrs, options) { if (this._isModel(attrs)) { if (!attrs.collection) attrs.collection = this; return attrs; } options = options ? _.clone(options) : {}; options.collection = this; var model = new this.model(attrs, options); if (!model.validationError) return model; this.trigger('invalid', this, model.validationError, options); return false; }, // Method for checking whether an object should be considered a model for // the purposes of adding to the collection. _isModel: function (model) { return model instanceof Backbone.Model; }, // Internal method to create a model's ties to a collection. _addReference: function(model, options) { this._byId[model.cid] = model; if (model.id != null) this._byId[model.id] = model; model.on('all', this._onModelEvent, this); }, // Internal method called every time a model in the set fires an event. // Sets need to update their indexes when models change ids. All other // events simply proxy through. "add" and "remove" events that originate // in other collections are ignored. _onModelEvent: function(event, model, collection, options) { if ((event === 'add' || event === 'remove') && collection !== this) return; if (event === 'destroy') this.remove(model, options); if (event === 'change-id') { if (collection != null) delete this._byId[collection]; if (model.id != null) this._byId[model.id] = model; } this.trigger.apply(this, arguments); }, // Internal method to sever a model's ties to a collection. _removeReference: function(model, options) { if (this === model.collection) delete model.collection; model.off('all', this._onModelEvent, this); }, }); // Underscore methods that we want to implement on the Collection. // 90% of the core usefulness of Backbone Collections is actually implemented // right here: var methods = ['forEach', 'each', 'map', 'collect', 'reduce', 'foldl', 'inject', 'reduceRight', 'foldr', 'find', 'detect', 'filter', 'select', 'reject', 'every', 'all', 'some', 'any', 'include', 'contains', 'invoke', 'max', 'min', 'toArray', 'size', 'first', 'head', 'take', 'initial', 'rest', 'tail', 'drop', 'last', 'without', 'difference', 'indexOf', 'shuffle', 'lastIndexOf', 'isEmpty', 'chain', 'sample', 'partition']; // Mix in each Underscore method as a proxy to `Collection#models`. _.each(methods, function(method) { if (!_[method]) return; Collection.prototype[method] = function() { var args = slice.call(arguments); args.unshift(this.models); return _[method].apply(_, args); }; }); // Underscore methods that take a property name as an argument. var attributeMethods = ['groupBy', 'countBy', 'sortBy', 'indexBy']; // Use attributes instead of properties. _.each(attributeMethods, function(method) { if (!_[method]) return; Collection.prototype[method] = function(value, context) { var iterator = _.isFunction(value) ? value : function(model) { return model.get(value); }; return _[method](this.models, iterator, context); }; }); // Helper function to correctly set up the prototype chain, for subclasses. // Similar to `goog.inherits`, but uses a hash of prototype properties and // class properties to be extended. //第一个参数是要扩展到原型上的对象, 第2个参数是静态方法扩展到构造函数上去的 var extend = function(protoProps, staticProps) { var parent = this; var child; // The constructor function for the new subclass is either defined by you // (the "constructor" property in your `extend` definition), or defaulted // by us to simply call the parent's constructor. if (protoProps && _.has(protoProps, 'constructor')) { child = protoProps.constructor; } else { child = function(){ return parent.apply(this, arguments); }; } // Add static properties to the constructor function, if supplied. //将静态方法和 parent上的静态方法一起扩展到child上面去 _.extend(child, parent, staticProps); // Set the prototype chain to inherit from `parent`, without calling // `parent`'s constructor function. //创建一个新的构造含糊Surrogate ; //this.constructor = child的意思是 Surrogate实例化后的对象 让对象的构造函数指向child // Surrogate的原型就是parent的原型 // 然后实例化给child的原型, // 这里不是直接从new parent给child.prototype 而是创建一个新的构造函数，我也不知道为啥要这样 var Surrogate = function(){ this.constructor = child; }; Surrogate.prototype = parent.prototype; child.prototype = new Surrogate; // Add prototype properties (instance properties) to the subclass, // if supplied. // 把第一个参数上的属性扩展到child.prototype if (protoProps) _.extend(child.prototype, protoProps); // Set a convenience property in case the parent's prototype is needed // later. // 拿一个属性引用父的原型, 以免以后要用到. child.__super__ = parent.prototype; return child; }; Backbone.Collection.extend = extend; })(); </script> </body> </html>
Collection的一些基本属性
length collection里面包含moldel的个数
models 该属性引用一个数组,数组里面就是model了
_byId 该属性引用一个对象,value就是model,key是该model的cid(或者是id,如果给model设置了id,就取id当key，否则用cid当key),
model 默认是Backbone.Model，可以被覆盖,如果传入的参数是这样的{name:"xx",age:"oo"}的对象,被实例化的对象就是用model这个基类来实例化的
Collection被实例化的过程以及 _reset,reset的方法
实例化的过程就是设置默认model,默认的model的作用是如果实例化后的colletion添加model的时候,如果传入的参数是object,则会用默认model实例化
设置comparator,
重置属性,
调用初始化方法initialize,
如果传入了值,重置值
_reset
this.length = 0; this.models = []; this._byId = {};
就是将一些属性设置成初始化的值
reset collection.reset([models], [options])
reset: function(models, options) { options || (options = {}); for (var i = 0, length = this.models.length; i < length; i++) { this._removeReference(this.models[i], options); } options.previousModels = this.models; this._reset(); models = this.add(models, _.extend({silent: true}, options)); if (!options.silent) this.trigger('reset', this, options); return models; }, _removeReference: function(model, options) { if (this === model.collection) delete model.collection; model.off('all', this._onModelEvent, this); },
它会遍历this.models里面的东西,然后执行this._removeReference,this._removeReference会把model对象的属性collection给删除掉(model在加入this.models里面的时候会加上collection这个属性,所以删除的时候要这个属性也干掉)，然后触发model的all监听的回调(如果model绑定了all)
用previousModels保存之前的this.models
如果传入的参数中有对象,要添加到this.models里面去,所以在调用this.add方法
silent表示是否触发事件,没有设置就触发reset监听的回调
一些例子
var c = new Backbone.Collection c.add({a:1}) var m = c.models[0]; alert(m.constructor === Backbone.Model) //true //可以看到默认的model是Backbone.Model var newModel = Backbone.Model.extend({}); var newC = new Backbone.Collection(null,{model:newModel}); newC.add({a:1}) var m = newC.models[0]; alert(m.constructor === newModel) //true alert(m.constructor === Backbone.Model)//false //可以看到默认的Backbone.Model变成了新的newModel了
var c = new Backbone.Collection({a:1}) console.log(c.models) //如果初始化的时候传一些数据进去,会自动变成model存在models里面的 var cc = new Backbone.Collection([{a:1},{b:1},{c:1}]) console.log(cc.models.length) //传入的数据也可以是一个数组
Collection的set ,add,remove,sort方法(set算是里面最重要的东西了)
set
首先会对传入的models进行一次转换,变成数组,方便进行下面的遍历
然后遍历传入的models,第一步对每个单独的model查看它是否由Backbone.Model实例化而来,如果是直接把id=model,然后通过该Collection上的modle的原型上的方法查看,看能否找到id
当查找完id后,判断该id是否已经存在了,如果存在，则看参数中是否传入options.remove,如果存在放入modelMap中,在看参数中是否有options.merge,如果有则直接molde.set来改变model的值
如果id不存在，而且传入的参数中有options.add,先对遍历的model做一些操作操作如下,如果attrs是真实的model,则把attrs.collection设置成当前的这个Collection,如果attrs不是model,则用当前的Collection.model实例化一个model,把attrs当参数传进去,然后将完成的model放入toAdd数组里面,然后看该model是否设置id属性,设置了id属性则this._byId通过model.id来引用model，没有设置id属性,则通过model.cid来引用model,然后给model绑定一个"on"的监听回调事件
然后看此次操作不是排序并且是添加或者删除,则吧model加到order数组中
操作完对models的遍历后,我们可能拿到这样几个东西modelMap,toAdd,order
如果参数传入的参数中options.remove为真,则遍历modelMap,进行删除,这个modelMap是通过已存在的model来得到的
如果toAdd，order里面有数据则进行添加..
然后再options里面是否设置了排序属性sort,如果设置了,则进行排序
set是给collection重新设置models,是重新设置,之前的models会全部清掉
var c = new Backbone.Collection(); c.set([{a:1},{b:1},{c:1}]); console.log(c.models) //有3个 c.set({d:1}); console.log(c.models) //只有1个了
add
add 很简单的就是设置set方法 把options参数里面的remove,merge设置成false，add设置成true
var c = new Backbone.Collection(); c.add([{a:1},new Backbone.Model(),new (Backbone.Model.extend({name:"newModel"}))()]) console.log(c.models) //存入moldes里面的model可以由不同的Model构建出来,
remove collection.remove(models, [options])
首先将传入的models进行遍历,删除collection里面的_byId对象的属性,然后从collection的models里面删除对应的项,触发model的remove事件
var c = new Backbone.Collection;
var m = new Backbone.Model;
m.on("remove",function(){
alert("你删除我了")
})
c.add(m);
alert(c.models.length);
c.remove(m);
alert(c.models.length);
comparator sort
comparator如果是一个function,则是规定models按什么样子的规则排序的函数
如果是一个字符窜,则按models里面有的有的属性进行排序
sort就是调用排序了,除了用comparator,还可以用reverse直接对models进行倒叙
comparator是函数
var c = new Backbone.Collection([ {name:"a1",age:18,level:"一般"}, {name:"a2",age:16,level:"很差"}, {name:"a3",age:28,level:"很好"}, {name:"a4",age:11,level:"较好"}, ],{ comparator : function(a,b){ return a.attributes.age-b.attributes.age } }) c.sort(); console.log(c.models); //这个可以按age排序 //用法和数组的sort一模一样的 //修改comparator可以自定义排序 很好 较好 一般 很差 c.comparator = function(a,b){ var obj = { "很好" : 5, "较好" : 4, "一般" : 3, "很差" : 2 } return obj[b.attributes.level] - obj[a.attributes.level] } c.sort(); console.log(c.models);
comparator是字符串
var c = new Backbone.Collection([ {name:"a1",age:18,level:"一般"}, {name:"a2",age:16,level:"很差"}, {name:"a3",age:28,level:"很好"}, {name:"a4",age:11,level:"较好"}, ],{ comparator : "age" }) c.sort(); console.log(c.models); //按age来排序 c.sort({reverse:true}); console.log(c.models); //进行倒序
Backbone.Collection扩展了很多数据的方法
['forEach', 'each', 'map', 'collect', 'reduce', 'foldl','inject', 'reduceRight', 'foldr', 'find', 'detect', 'filter', 'select','reject', 'every', 'all', 'some', 'any', 'include', 'contains', 'invoke','max', 'min', 'toArray', 'size', 'first', 'head', 'take', 'initial', 'rest','tail', 'drop', 'last', 'without', 'difference', 'indexOf', 'shuffle','lastIndexOf', 'isEmpty', 'chain', 'sample', 'partition'];
还扩展了一些underscore的方法
['groupBy', 'countBy', 'sortBy', 'indexBy']