与父值匹配的角度嵌套ng-repeat过滤器项

Question

我传递了2个数组到我的视图.我希望我的嵌套循环只显示它的parent_id值与parent.id匹配的位置.例如.

arr1 = {"0":{"id":326,"parent_id":0,"title":"Mellow Mushroom voucher","full_name":"Patrick","message":"The voucher says $10 Voucher; some wording on the printout says, \"This voucher is valid for $20 Pizza\" but my purchase price or amount paid also says $20. Shouldn't that be $10","type":"Deals"}};
arr2 = {"0":{"id":327,"parent_id":326,"title":"Re: Mellow Mushroom voucher","full_name":"Patrick Williams","message":"Some message here","type":null};

...
<div data-ng-repeat = "parent in arr1">
<span>{{parent.title}}<span>
    <div data-ng-repeat="child in arr2 | only-show-where-child.parent_id == parent.id">
        <li>{{child.body}}</li>
    </div>
</div>

这是角度中的可能/最佳实践吗？我应该在将节点传递给角度之前过滤节点中的对象吗？谢谢!

Answer 1

而不是使用过滤器,data-ng-if可以实现相同的结果.

<div data-ng-repeat="parent in arr1">
  <span>{{parent.title}}<span>
  <div data-ng-repeat="child in arr2" data-ng-if="child.parent_id == parent.id">
    <li>{{child.body}}</li>
  </div>
</div>

Answer 2

有几种方法可以做到......你可以创建一个只返回孩子的函数:

$scope.getChildren = function(parent) {
  var children = [];
  for (var i = 0; i < arr2.length; i++) {
    if (arr2[i].parent_id == parent.id) {
      children.push(arr2[i]);
    }
  }
  return children;
};

HTML:

<div ng-repeat="child in getChildren(parent)">

你可以定义一个过滤器来做同样的事情:

myApp.filter('children', function() {
  return function(input, parent) {
    var children = [];
    for (var i = 0; i < input.length; i++) {
      if (input[i].parent_id == parent.id) {
        children.push(input[i]);
      }
    }
    return children;
  };
});

HTML:

<div ng-repeat="child in arr2|children:parent">

这两种方法都会执行每个摘要周期.如果您有大量元素,那么您肯定希望提高性能.我认为最好的方法是在获得结果时预先处理这些结果,在arr1中为每个对象添加一个子数组,只有它的子进程(这里使用array.filter而不是for循环和array.forEach):

arr1.forEach(function(parent) {
  parent.children = arr2.filter(function(value) {
    return value.parent_id === parent.id;
  };
});

然后在html中你已经在使用父级了,所以你可以重复它的子属性:

<div ng-repeat="child in parent.children">