在 BoilerplateJS 中传递 KnockoutJS 视图模型

Question

嵌套组件也预设了嵌套视图模型。

然而，在示例组件中，我没有看到这种依赖出现（除了 BackboneJS TODO 应用程序，对于 KO 用户来说不是很清楚）。

您能否详细说明如何进行这样的设计，例如对于一个集合：

• ItemViewModel 具有属性 Name 和 IsSelected
• CollectionViewModel 有一个 Items 属性，其中包含 ItemViewModel 和 SelectedCount 的集合，该集合是通过计算选择的项目数来计算的。 （我知道这可以通过 KO 以更简单的方式完成，但只是为了说明。

Answer 1

Viewmodels (VM) 只是对象（使用ko.applyBindings() 绑定） - 这意味着您可以将 VM 任意嵌套到父对象中（@Hasith 所说的）。您只需将 一个 父对象传回 Boilerplate。忍受一些超注释代码：

// Let's assume you have your items nicely formatted in an array 
// data source (and technically the objects in this array can be 
// considered 'dumb' viewmodels)
var items = [
  {Name:'a',isSelected:false}, 
  {Name:'b',isSelected:true}
  ]

// We can apply some bindings to make 'smarter' viewmodels
// One approach is just to map using rocking KO mapping plugin
var koMapItems = ko.mapping.fromJS( items )

// You could skip the mapping plugin and go for broke
// creating your own VM mappings manually
// (you could do this using the mapping plugin with less work)
var goforbrokeVM = function( item )
{
  var _name = ko.observable( item.Name )
  var _dance = function() { return _name+' is space monkey' }

  return {
    Name: _name,
    isSelected: ko.observable( item.isSelected ),
    spaceMonkey: _dance
  }
}
// Don't forget to assign and create your goforbrokeVMs
var epicItemVMs = []
for (var i=0;i<items.length;i++) 
  epicItemVMs.push( new goforbrokeVM( items[i]) )


// Now the interesting part, lets create a 'child' VM that
// we can embed in another VM. Notice this VM has as a
// property an array of VMs itself.
var childVM = {
  elements: epicItemVMs,
  // A sub method, because we can
  otherMethod: function() { return 'wat' }
}

// And ultimately our 'master' VM with its own properties
// including the nested child VM we setup above (which you'll
// remember contains its own sub VMs)
var ParentVM = {
  // And its own property
  parentPropA: ko.observable('whatever'),

  // Oooow look, a list of alternative ko.mapping VMs
  simpleMappedItems: koMapItems,

  // And a nested VM with its own nested goforbrokeVMs
  nested: childVM
}

// Apply your master viewmodel to the appropriate DOM el.
ko.applyBindings( ParentVM, document.getElementById('items'))

还有你的 HTML：

<div id="items">
  <span data-bind="text: parentPropA"></span>

  <!-- Step through one set of items in ParentVM -->
  <div data-bind="foreach: simpleMappedItems">
    <input type="checkbox" data-bind="checked: isSelected">
    <span data-bind="text: Name"></span>
  </div>

  <!-- Or jump into the nested models and go crazy -->
  <!-- ko with: nested -->
    <div data-bind="foreach:elements">
      <div data-bind="text: spaceMonkey"></div>
    </div>
    <div data-bind="text: otherMethod"></div>
  <!-- /ko -->
</div>

通过这种方式，您可以将单个对象（在本例中为 ParentVM）传递给带有尽可能多的嵌套视图模型的样板。

用于淘汰赛的地图插件信息在这里：http://knockoutjs.com/documentation/plugins-mapping.html

Answer 2

“todo”示例是通过采用 Addy Osmani 的实现来完成的。 还有一个knockoutjs的实现here。