使用knockout映射插件将深层次对象映射到自定义类

Question

使用淘汰赛映射插件（http://knockoutjs.com/documentation/plugins-mapping.html）可以映射深层分层对象吗？

如果我有一个具有多个级别的对象：

var data = {
    name: 'Graham',
    children: [
        {
            name: 'Son of Graham',
            children: [
                {
                    name: 'Son of Son of Graham',
                    children: [
                        {
                            ... and on and on....
                        }
                    ]

                }
            ]
        }
    ]
}

如何在javascript中将其映射到我的自定义类：

var mapping = {
    !! your genius solution goes here !!

    !! need to create a myCustomPerson object for Graham which has a child myCustomerPerson object 
    !! containing "Son of Graham" and that child object contains a child myCustomerPerson 
    !! object containing "Son of Son of Graham" and on and on....

}

var grahamModel = ko.mapping.fromJS(data, mapping);

function myCustomPerson(name, children)
{
     this.Name = ko.observable(name);
     this.Children = ko.observableArray(children);
}

映射插件可以递归地将此数据映射到我的自定义对象的层次结构中吗？

Answer 1

像这样（Live copy on js fiddle）：

CSS：

.left {
    float: left;
}

.clear {
    clear: both;
}​

HTML：

<p>Current:&nbsp;
    <a href="#" data-bind="visible: (stack.length > 0), text: selectedNode().name, click: selectParentNode"></a>
    <span data-bind="visible: (stack.length <= 0), text: selectedNode().name"></span>
</p>
<p class="left">Children:&nbsp;</p>
<ul class="left" data-bind="template: {name: 'childList', foreach: selectedNode().children}"></ul>

<script type="text/html" id="childList">
    <li data-bind="click: function(){nodeViewModel.selectChildNode($data)}">
        <a href="#">A${name}</a>
    </li>
</script>

<br /><br />
<ul class="clear" data-bind="template: {name: 'backBtn'}"></ul>

<script type="text/html" id="backBtn">
    <a href="#" data-bind="visible: $data.selectedNode().back, click: function() { nodeViewModel.selectBackNode($data.selectedNode().back) }">Back</a>
</script>​

JavaScript的：

var node = function(config, parent) {
    this.parent = parent;
    var _this = this;

    var mappingOptions = {
        children: {
            create: function(args) {
                return new node(args.data, _this);
            }
        }
    };

    ko.mapping.fromJS(config, mappingOptions, this);
};

var myModel = {
    node: {
        name: "Root",
        children: [
            {
            name: "Child 1",
            back: 1,
            children: [
                {
                name: "Child 1_1",
                back: 1,
                children: [
                    {
                    name: "Child 1_1_1",
                    back: 4,
                    children: [
                        ]},
                {
                    name: "Child 1_1_2",
                    back: 2,
                    children: [
                        ]},
                {
                    name: "Child 1_1_3",
                    back: 1,
                    children: [
                        ]}
                    ]}
            ]},
        {
            name: "Child 2",
            back: 1,
            children: [
                {
                name: "Child 2_1",
                back: 1,
                children: [
                    ]},
            {
                name: "Child 2_2",
                back: 1,
                children: [
                    ]}
            ]}
        ]
    }
};

var viewModel = {

    nodeData: new node(myModel.node, undefined),

    selectedNode: ko.observable(myModel.node),

    stack: [],

    selectBackNode: function(numBack) {

        if (this.stack.length >= numBack) {
            for (var i = 0; i < numBack - 1; i++) {
                this.stack.pop();
            }
        }
        else {
            for (var i = 0; i < this.stack.length; i++) {
                this.stack.pop();
            }
        }

        this.selectNode( this.stack.pop() );
    },

    selectParentNode: function() {
        if (this.stack.length > 0) {
            this.selectNode( this.stack.pop() );
        }
    },

    selectChildNode: function(node) {
        this.stack.push(this.selectedNode());
        this.selectNode(node);
    },

    selectNode: function(node) {
        this.selectedNode(node);
    }

};

window.nodeViewModel = viewModel;
ko.applyBindings(viewModel);​

这个示例只是映射了一组无限嵌套的JSON数据，我可以说实际上在应用程序中使用这个确切的代码非常有效。

一些额外的功能，如

selectBackNode和selectParentNode

允许你向后移动树。

在导航示例时，父标签变为允许上升一级的链接，并且一些叶节点有一个后退按钮，允许它们向上移动树上一定数量的级别。

- 编辑 -

如果您的叶节点没有子数组，则可能会出现模型中不存在其他数据的问题。

Answer 2

根据我的经验，我会说它应该没有任何问题。

我会使用以下行 -

var grahamModel = ko.mapping.fromJS(data);

然后在下一行设置断点，查看调试器中生成的对象（chrome或FF + Firebug效果最佳）。通过这种方式，您将知道ko.mapping是否会生成满足您需求的视图模型。

通常，它会生成一个对象，其中只有端点（带有值的变量）是ko.observables。您可以用于导航数据的任何其他数据时间（如... children: [...）都显示为普通的javaScript对象。

Answer 3

如果您不想要嵌套的mappingOptions（为每个节点级别创建一个ko映射对象），您可以利用create的ko映射选项使您可以访问父对象。像这样：

function Folder(parent,data) {
    var self = this;
    self.parent = parent;
    ko.mapping.fromJS(data, self.map, self);
}

Folder.prototype.map = {
    'folders': {
        create: function(options) {
            var folder = new Folder(options.parent,options.data);
            return folder;
        }
    }
}

var data = { name:"root", folders: [ {name:"child", folders: [] } ] };
var root = new Folder(null, data);

这样你在类原型中只有一份地图副本（或者可以是任何函数）。如果你想让Folder.parent成为一个observable，你可以在map函数中做data.parent = parent;而不是作为参数传递给你的Folder构造函数，或者在文件夹构造函数中做而不是self.parent = parent;

Answer 4

我使用此answer中的方法创建了一个复选框的层次结构，其中包含子项的节点是可折叠的，当您选中/取消选中父项时，其后代将被选中/取消选中。

查看模型

var Category = function(data, parent) {
    var self = this;
    self.name = data.name;
    self.id = data.id;
    self.parent = parent;
    self.categoryChecked = ko.observable(false);
    ko.mapping.fromJS(data, self.map, self);
};

// This will add a "map" to our category view model
Category.prototype.map = {
    'sub_categories' : {
        create: function(options){
            var category = new Category(options.data, options.parent);
            category.parent.categoryChecked.subscribe(function(value){
                category.categoryChecked(value);
            });
            return category;
        }
    }
};  

HTML（查看）

    <div data-role="panel" id="left-panel" data-position="left" data-position-fixed="false" data-theme="b">
            <div data-role="collapsible-set" data-bind="template: {name: 'category_collapsible', foreach: sub_categories}" data-mini="true" id="categories" data-iscroll> </div>
        </div><!-- END left panel -->

        <script type="text/html" id="category_collapsible">
            <div class="category_collapsible" data-mini="true" data-content-theme="b" data-inset="true" data-iconpos="right">
                <h3>     
                    <input data-role="none" data-them="b" data-bind='checked: categoryChecked, jqmChecked: true, attr: {id: "category_checkbox_"+id}' class="chk_category" type="checkbox" />
                    <label data-bind='attr: {for: "category_checkbox_"+id}'><span data-bind="text: name"> </span></label>
                </h3>
                <ul data-role="listview" data-bind="template: {name: 'category_list', foreach: sub_categories}">

                </ul>
            </div>
        </script><!-- END category_collapsible template -->

        <script type="text/html" id="category_list">
            <!-- ko if: sub_categories().length==0 -->
                <li data-theme="c">
                    <input data-role="none" data-theme="c" data-bind='checked: categoryChecked, jqmChecked: true, attr: {id: "category_checkbox_"+id}' class="chk_category" type="checkbox"/>
                    <label data-corners="false" data-bind='attr: {for: "category_checkbox_"+id}'>
                        <span data-bind="text: name"> </span>
                    </label>        
                </li>
            <!-- /ko -->
            <!-- ko if: sub_categories().length>0 -->
                <li data-theme="c" data-bind="template: {name: 'category_collapsible', data: $data}"></li>
            <!-- /ko -->
        </script>