Dependent/Cascading Aurelia 中的下拉列表

Question

我想在 Aurelia 中创建依赖下拉菜单。

我所说的依赖下拉菜单的意思是，如果您单击第一个下拉菜单中的项目，那么第二个下拉菜单中的选项将根据您单击的内容进行过滤。如果您查看我的 js-fiddle，您会注意到，如果您在第一个下拉列表中选择 select Toyota，则第二个下拉列表中会显示 Toyota 车型（Corolla、Camry 等）。如果您在第一个下拉列表中 select 本田，则第二个下拉列表中会填充本田车型（雅阁、思域等）。你明白了。

在 Angular 中执行此操作非常简单，只需要很少的代码，我想知道在 Aurelia 中执行此操作是否也简单明了。就如何在 Aurelia 中执行此操作而言，我无法找到太多资源。下面的 fiddle 准确地展示了我想要完成的事情（除了我想在 Aurelia 中完成，当然不是 Angular）。任何帮助将非常感激。谢谢！

https://jsfiddle.net/nhunt3/wjvvjwzx/

HTML:

<div ng-app="myApp" ng-controller="myController">
My Cars
<br />
<table>
  <thead>
    <tr>
      <td>Make</td>
      <td>Model</td>
    </tr>
  </thead>

  <tbody>
    <tr ng-repeat="car in myCars track by car.uid">
      <td>
        <select ng-model="car.MakeUID" ng-options="make.uid as make.name for make in makes" />
      </td>

      <td>
        <select
        ng-model="car.ModelUID"
        ng-options="model.uid as model.name for model in models | filter: { parentID: car.MakeUID } : true" />
      </td>
    </tr>
  </tbody>
</table>   
</div>

JavaScript:

// the main (app) module
var myApp = angular.module("myApp", []);

angular.module('myApp', []).controller('myController', function($scope) {
    $scope.makes = [
        {name:'Toyota', uid:1},
        {name:'Honda', uid:2},
        {name:'Ford', uid:3}
    ];

  $scope.models = [
            {name:'Yaris', uid:1, parentID:1},
        {name:'Corolla', uid:2, parentID:1},
        {name:'Camry', uid:3, parentID:1},
        {name:'Highlander', uid:4, parentID:1},
        {name:'Accord', uid:5, parentID:2},
        {name:'Civic', uid:6, parentID:2},
        {name:'Pilot', uid:7, parentID:2},
        {name:'Focus', uid:8, parentID:3},
        {name:'Fiesta', uid:9, parentID:3},
        {name:'Fusion', uid:10, parentID:3},
        {name:'F-150', uid:10, parentID:3}
    ];

  $scope.myCars = [
        {uid:1, MakeUID:1, ModelUID:2},
        {uid:2, MakeUID:1, ModelUID:3},
        {uid:3, MakeUID:3, ModelUID:8}
    ];
});

Answer 1

找到此主题的其他用户：

app.html

<template>
  <require from="./filter"></require>
  <table>
  <thead>
    <tr>
      <td>Make</td>
      <td>Model</td>
    </tr>
  </thead>
  <tbody>
    <tr repeat.for="car of myCars">
      <td>
        <select value.bind="car.MakeUID" change.delegate="resetModel(car)">
          <option value="0">select one of ...</option>
          <option repeat.for="make of makes" model.bind="make.uid">${make.name}</option>
        </select>
      </td>
      <td>
        <select value.bind="car.ModelUID">
          <option value="0">select one of ...</option>
          <option repeat.for="model of models | filter:'parentID':car.MakeUID" model.bind="model.uid">${model.name}</option>
        </select>
      </td>
    </tr> 
  </tbody>
</template>

app.js

export class App { 
    makes = [
        {name:'Toyota', uid:1},
        {name:'Honda', uid:2},
        {name:'Ford', uid:3}
    ];

    models = [
        {name:'Yaris', uid:1, parentID:1},
        {name:'Corolla', uid:2, parentID:1},
        {name:'Camry', uid:3, parentID:1},
        {name:'Highlander', uid:4, parentID:1},
        {name:'Accord', uid:5, parentID:2},
        {name:'Civic', uid:6, parentID:2},
        {name:'Pilot', uid:7, parentID:2},
        {name:'Focus', uid:8, parentID:3},
        {name:'Fiesta', uid:9, parentID:3},
        {name:'Fusion', uid:10, parentID:3},
        {name:'F-150', uid:10, parentID:3}
    ];

    myCars = [
        {uid:1, MakeUID:1, ModelUID:2},
        {uid:2, MakeUID:1, ModelUID:3},
        {uid:3, MakeUID:3, ModelUID:8}
    ];

    resetModel(car) {
      car.ModelUID = 0;
    }
}

filter.js

export class FilterValueConverter {
  toView(array, propertyName, filter_on) {
    return array.filter(i => i[propertyName] == filter_on);
  }
}

旧答案

我认为这与您在 Aurelia 中的 Angular 代码相同：

<template>
  <require from="./filter"></require>
  <table>
  <thead>
    <tr>
      <td>Make</td>
      <td>Model</td>
    </tr>
  </thead>
  <tbody>
    <tr repeat.for="car of myCars">
      <td>
        <select value.bind="car.MakeUID" ref="selected_car">
          <option repeat.for="make of makes" value.bind="make.uid">${make.name}</option>
        </select>
      </td>

      <td>
        <select value.bind="car.ModelUID">
          <option repeat.for="model of models | filter:'parentID':selected_car.value">${model.name}</option>
        </select>
      </td>
    </tr> 
  </tbody>
</template>

你还需要这个过滤器：

export class FilterValueConverter {
  toView(array, propertyName, filter_on) {
    return array.filter(i => i[propertyName] == filter_on);
  }
}

https://gist.run/?id=91b23375e0b73afe7f21825f67cfeabf

Answer 2

我为你完成了你的解决方案，但你给了我一个非常关键的开始。我在你的 make td 中删除了一个不必要的 ref 并添加了一对 model.binds 并更改了你的过滤器匹配的内容。

查看我从你那里分叉出来的最终要点。

https://gist.run/?id=e0b9c401370a954b594ad2415d983099

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