如果绑定在KnockoutJS中不起作用,则无容器

时间:2016-03-30 12:39:49

标签: javascript node.js knockout.js

我最近想要显示一个特定属性(如果已定义),如果未定义,我想显示一个带有一些指令的DIV元素。

但我无法理解这一点;我已尝试使用$root甚至绑定属性,但没有成功。

以下是我的代码示例:

function InvestigatorInfo() {
  var self = this;
  self.Name = ko.observable();
  self.Description = ko.observable();
  self.TypeName = ko.observable();
  self.AssemblyName = ko.observable();
  self.ResultType = ko.observable();
  self.EnumTypeName = ko.observable();
  self.Obsolete = ko.observable();
  self.InvestigatorType = ko.observable();

  self.Properties = ko.observable();
  self.Requires = ko.observable();
}
InvestigatorInfo.prototype.fromJS = function(data) {
  var self = this;
  self.Name(data.Name || "");
  self.Description(data.Description || "");
  self.TypeName(data.TypeName || "");
  self.AssemblyName(data.AssemblyName || "");
  self.ResultType(data.ResultType || "");
  self.EnumTypeName(data.EnumTypeName || "");
  self.Obsolete(data.Obsolete || "");
  self.InvestigatorType(data.InvestigatorType || "");

  self.Properties(data.Properties.Properties || []);
  self.Requires(data.Requires.Interfaces || []);
}

我的索引:

<ul class="collapsible" data-collapsible="accordion" data-bind="foreach:InvestigatorInfos">
  <li>
    <div class="collapsible-header">
      <i class="material-icons">view_quilt</i>
      <p class="blue-text" data-bind="text: TypeName"></p>
    </div>
    <div class="collapsible-body">

      <p class="style_p_row" ><b>AssemblyName:</b> <span data-bind="text: AssemblyName"></span></p>
                  <!-- ko if:Description -->
                  <p class="style_p_row" ><b>Description:</b> <span data-bind="text: Description"></span></p>
                  <!-- /ko -->
                  <!-- ko if:EnumTypeName -->
                  <p class="style_p_row" >
                  <b>EnumTypeName: </b><span data-bind="text: EnumTypeName"></span></p>
                  <!-- /ko -->
                  <p class="style_p_row" >
                  <b>InvestigatorType:</b> <span class="investigatortype-class" data-bind="text:investigatorName[InvestigatorType]"></span></p>
                  <p class="style_p_row" ><b>Name: </b><span data-bind="text: Name"></span></p>
                   <!-- ko if:Obsolete -->
                  <p class="style_p_row" ><b>Obsolete: </b><span data-bind="text: Obsolete"></span></p>
                   <!-- /ko -->
                  <p class="style_p_row" ><b>TypeName: </b><span data-bind="text: TypeName"></span></p>
                  <!-- ko if:ResultType -->
                  <p class="style_p_row" ><b>ResultType: </b><span data-bind="text: resultName[ResultType]"></span></p>
                  <!-- /ko -->

      <!-- ko ifnot:Properties-->
      <p class="blue-text padding_p">Properties</p>
      nothing is set
      <!-- /ko -->
      <!-- ko if: Properties-->
      <table class="bordered">
        <thead>
          <tr>
            <th data-field="Name">Name</th>
            <th data-field="Converter">Converter</th>
            <th data-field="ValidationName">ValidationName</th>
            <th data-field="EnumTypeName">EnumTypeName</th>
          </tr>
        </thead>
        <tbody data-bind="foreach: Properties">
          <tr>
            <td><span data-bind="text: Name"></span>
            </td>
          </tr>
        </tbody>
      </table>
      <!-- /ko -->
    </div>
    </li>
    </ul>

Properties中的ko if: Properties部分始终显示,即使其后面的数组中没有值,也不会显示ko ifnot: Properties中定义的元素。

JSON数据:

{
    "BrickInfos":  {
                       "BrickInfos":  [
                                          {
                                              "Properties":  {
                                                                 "Properties":  [

                                                                                ]
                                                             },
                                              "Implements":  {
                                                                 "Interfaces":  [
                                                                                    {
                                                                                        "TypeName":  "ITSR2.Bricks.Access.IAccessBareBoneBrick"
                                                                                    },
                                                                                    {
                                                                                        "TypeName":  "ITSR2.Bricks.Access.IAccessAppBrick"
                                                                                    }
                                                                                ]
                                                             },
                                              "Name":  "AccessBareBoneApp",
                                              "Description":  "",
                                              "TypeName":  "ITSR2.Bricks.Access.AccessBareBoneApp",
                                              "AssemblyName":  "ITSR2.Bricks.MSOffice, Version=3.0.0.0, Culture=neutral, PublicKeyToken=null",
                                              "Obsolete":  false
                                          },
                                          {
                                              "Properties":  {
                                                                 "Properties":  [
                                                                                    {
                                                                                        "Name":  "MainFile",
                                                                                        "Description":  "",
                                                                                        "ValidationType":  4,
                                                                                        "Converter":  8,
                                                                                        "EnumTypeName":  ""
                                                                                    }
                                                                                ]
                                                             },
                                              "Implements":  {
                                                                 "Interfaces":  [
                                                                                    {
                                                                                        "TypeName":  "ITSR2.Bricks.Access.IAccessBrick"
                                                                                    },
                                                                                    {
                                                                                        "TypeName":  "ITSR2.Bricks.Access.IAccessAppBrick"
                                                                                    }
                                                                                ]
                                                             },
                                              "Name":  "AccessFile",
                                              "Description":  "",
                                              "TypeName":  "ITSR2.Bricks.Access.AccessFile",
                                              "AssemblyName":  "ITSR2.Bricks.MSOffice, Version=3.0.0.0, Culture=neutral, PublicKeyToken=null",
                                              "Obsolete":  false
                                          },
                                     ]
                    }
}  

1 个答案:

答案 0 :(得分:1)

您的Properties属性是observable,看起来像是一个数组,并且设置为data.Properties.Properties或空数组([])。

[]"truthy" value,因此即使代码已将[]分配给Properties,淘汰赛if绑定也会将其视为已填充。你需要检查它的长度:

<!-- ko if:Properties().length == 0-->

注意() - 我们需要调用observable来获取底层数组 - observable本身没有length属性。

关于您的更新,以Obsolete为例,您已将其传递给false。这意味着:

<!-- ko if: Obsolete -->

永远不会显示它的内容,因为它显然false。您需要将其定制为您期望的值 - 因为您将默认值设置为"",您可以检查:

<!-- ko ifnot: Obsolete() === "" -->

因此,如果它特别是一个空白字符串,它将无法显示,将显示任何其他内容。您的每个属性都需要进行类似的检查,具体取决于您传递给他们的内容以及是否有任何&#34;有效&#34;您想要显示的值最终可能会被视为虚假值。