backbone collection集合

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最新推荐文章于 2024-11-26 16:51:13 发布

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分类专栏： javascript 文章标签： backbone web MVC

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本文介绍了Backbone.js中模型(Model)与集合(Collection)的概念及其使用方法，包括模型的创建、集合的定义、集合中模型的操作如排序、筛选等。

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集合是模型的组合

eg:

Model: Student, Collection: ClassStudents
Model: Todo Item, Collection: Todo List
Model: Animal, Collection: Zoo

通常你只会使用一种类型的模型,但模型本身并不局限于一种集合;

Model: Student, Collection: Gym Class (体育课)
Model: Student, Collection: Art Class （艺术课）
Model: Student, Collection: English Class （英语课）

我们创建一个歌手和歌曲名的模型Song，这个模型属于Album唱片集这个集合

var Song = Backbone.Model.extend({
        defaults: {
            name: "Not specified",
            artist: "Not specified"
        },
        initialize: function(){
            console.log("Music is the answer");
        }
    });

    var Album = Backbone.Collection.extend({
        model: Song
    });

    var song1 = new Song({ name: "How Bizarre", artist: "OMC" });
    var song2 = new Song({ name: "Sexual Healing", artist: "Marvin Gaye" });
    var song3 = new Song({ name: "Talk It Over In Bed", artist: "OMC" });

    var myAlbum = new Album([ song1, song2, song3]);
    console.log( myAlbum.models ); // [song1, song2, song3]

toJSON

toJSO方法返回集合中包含哈每个模型哈希属性的数组。此方法通常用于对集合整体做序列化和持久化。

var song = new Backbone.Collection([  
  {name: "Flatts"},  
  {name: "OMC"},  
  {name: "Jackson"}  
]);  
JSON.stringify(song); //[{"name":"Flatts"},{"name":"OMC"},{"name":"Jackson"}] 
song.toJSON();        //[Object { name="Flatts"}, Object { name="OMC"}, Object { name="Jackson"}]

比较器Comparator

var student  = Backbone.Model;  
var students = new Backbone.Collection;  
students.comparator = 'name';  //按name属性正序排序，
students.add(new student({name: "name1", roll: 9}));  
students.add(new student({name: "name2", roll: 5}));  
students.add(new student({name: "name3", roll: 1}));  
//从集合中的每个模型采摘一个属性，这等同于从迭代器调用Map并返回单一属性
students.pluck('roll'); // [9, 5, 1]

采摘
Pluck：从集合中的每个模型采摘一个属性，这等同于从迭代器调用Map并返回单一属性。

var song = new Backbone.Collection([  
      {name: "Flatts"},  
      {name: "OMC"},  
      {name: "Jackson"}  
]);  
var names = song.pluck("name");  
JSON.stringify(names);   //["Flatts","OMC","Jackson"]

Where
where：返回集合中所有匹配传递的属性的模型的数组，使用了过滤器。

var song = new Backbone.Collection([  
      {name: "Yes I Do",      artist: "Flatts"},  
      {name: "How Bizarre",    artist: "How Bizarre"},  
      {name: "What Hurts the Most",     artist: "Flatts"},  
]);  
var artists = song.where({artist: "Flatts"});  
JSON.stringify(artists);  //[{"name":"Yes I Do","artist":"Flatts"},{"name":"What Hurts the Most","artist":"Flatts"}]