binding - knockout 动态绑定(bind)问题

Question

考虑以下通过 knockout 映射插件生成的 ViewModel。

var originalData = {

"QuoteSelectedViewModel": {
  "ProductName": "Select",      
  "CoverQuotesViewModel": [
     {
        "Code": 1,
        "Label": "Première Assistance 24h/24 (GRATUITE)",
        "IsMandatory": true,
        "IsSelected": true,            
        "DependsOn": []
     },
     {
        "Code": 2,
        "Label": "Assistance PLUS 24h/24",
        "IsMandatory": false,
        "IsSelected": false,          
        "DependsOn": []
     },
      {
        "Code": 8,
        "Label": "Heurts Animaux / Force de la Nature",
        "IsMandatory": false,
        "IsSelected": false,        
        "DependsOn": [
           2
        ]
     },
  ]}
}

var viewModel = ko.mapping.fromJS(originalData);

ko.applyBindings(viewModel);


<div data-bind="with: QuoteSelectedViewModel">
selected quote is : <span data-bind="text: ProductName"></span>
 <!-- ko foreach: CoverQuotesViewModel -->
<br/>    
  <div data-bind: if: IsVisible>
    <input type="checkbox" data-bind="checked: IsSelected"></input>
    <input type="text" data-bind="value: Label, enable: IsSelected"></input>
  </div>
<!-- /ko -->
</div>

现在，我想在 IsVisible 返回 false 时隐藏 div。 IsVisible 尚不存在，它应该是 CoverQuotesViewModel 数组的每个元素上的计算可观察函数。

如何在每个元素上生成这个计算的可观察函数？

谢谢

[编辑] 我在这里添加了一个 jsfiddle:http://jsfiddle.net/graphicsxp/fpKWM/

[编辑2] 实际上， knockout 文件清楚地说明了如何做到这一点:

Of course, inside the create callback you can do another call to ko.mapping.fromJS if you wish. A typical use-case might be if you want to augment the original JavaScript object with some additional computed observables:

var myChildModel = function(data) { ko.mapping.fromJS(data, {}, this);

this.nameLength = ko.computed(function() {
    return this.name().length;
}, this); }

[编辑]

以下是遵循 Paul 建议的完整代码: (getQuotesSuccess 是一个 AJAX 成功处理程序)

viewModel.getQuotesSuccess = function (result) {
var myCoverQuotesViewModel = function (data, parent) {
    var self = this;
    ko.mapping.fromJS(data, {}, this);

    self.IsVisible = ko.computed(function () {
        var visible = true;
        if (self.DependsOn().length > 0) {
            $.each(self.DependsOn(), function (index, value) {
                var dependency = viewModel.QuoteSelectedViewModel().CoverQuotesViewModel.filterByProperty("Code", value);
                if (dependency().length > 0) {
                    visible = visible & dependency()[0].IsSelected();
                } else {
                    visible = false;
                }
            });
        }

        return visible;

    }, this);
}

var mapping = {
    'CoverQuotesViewModel': {
        create: function (options) {
            return new myCoverQuotesViewModel(options.data, options.parent);
        }
    }
}

  ko.mapping.fromJS(result, mapping, viewModel);
};

Answer 1

好吧，回到我之前的答案，加上你的修改，所以其他看到这个答案的人实际上得到了正确的版本!

您需要创建一个子 viwe 模型，并使用映射插件自动填充它，然后添加到您的计算可观察对象中:

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

    // Copy the data to each property.
    self.IsVisible = ko.computed(function()
    {
            // your logic for each quote
    });
}

然后您需要使用一个创建映射来映射主视图模型，并在此创建您的 subview 模型:

var mapping = {
    'CoverQuotesViewModel': {
        create: function(options) {
            var model = new CoverQuotesViewModel(options.data);
            return model;
        }
    }
}
var viewModel = ko.mapping.fromJS(data, mapping);

您不需要将 this 传递给计算，因为您引用的是 self，这是您存储的 this 版本。