ng-repeat a single element over nested objects

问题

Say I have an object with keys corresponding to products and values corresponding to objects which in turn have keys corresponding to price points at which those products have sold, and values corresponding to amount sold.

For example, if I sold 10 widgets at $1 and 5 widgets at $2, I'd have the data structure:

{ 'widget': {'1': 10, '2': 5} }

I'd like to loop over this structure and generate rows in a table such as this one:

thing   price  amount
---------------------
widget  $1     10
widget  $2     5

In Python it's possible to nest list comprehensions to traverse lists data structures like this. Would such a thing be possible using ng-repeat?

回答1:

ng-repeat does not currently have a possible way to complex iterate inside objects (the way it's possible in python). Check out the ng-repeat source code and note that the regex expression matched is:

(key, value) in collection - and that they push into the key array and assign to the value list, and so you cannot possibly have a complex ng-repeat sadly...

There are basically 2 types of solutions which were already answered here:

1. Nested ng-repeat like the first answer suggested.
2. Rebuilding your data object to fit 1 ng-repeat like the second answer suggested.

I think solution 2 is better as I like to keep my sorting & coding logic inside the controller, and not deal with it in the HTML document. This will also allow for more complex sorting (i.e based on price, amount, widgetName or some other logic).

Another thing - the second solution will iterate over possible methods of a dataset (as hasOwnProperty wasn't used there).

I've improved the solution in this Plunker (based on the finishingmove Plunker) in order to use angular.forEach and to show that the solution is rather simple but allows for complex sorting logic.

$scope.buildData = function() {

  var returnArr = [];

  angular.forEach($scope.data, function(productData, widget) {
      angular.forEach(productData, function( amount, price) {
        returnArr.push( {widgetName: widget, price:price, amount:amount});            
      });
  });
   //apply sorting logic here
  return returnArr;
};
$scope.sortedData = $scope.buildData();

and then in your controller:

<div ng-controller="MyCtrl">
    <table>
      <thead>
        <tr>
          <td>thing</td>
          <td>price</td>
          <td>amount</td>
        </tr>
      </thead>
      <tbody>
      <tr ng-repeat="item in sortedData">
        <td>{{ item.widgetName }}</td>
        <td>{{ item.price|currency }}</td>
        <td>{{ item.amount }} </td>
        </tr>
      </tbody>
    </table>
</div>

回答2:

How about this?

http://plnkr.co/edit/ZFgu8Q?p=preview

Controller:

$scope.data = {
  'widget1': {
    '1': 10,
    '2': 5
  },
  'widget2': {
    '4': 7,
    '6': 6
  }
};

View:

<div ng-controller="MyCtrl">
    <table>
      <thead>
        <tr>
          <td>thing</td>
          <td>price</td>
          <td>amount</td>
        </tr>
      </thead>
      <tbody ng-repeat="(productName, productData) in data">
        <tr ng-repeat="(price, count) in productData">
            <td>{{productName}}</td>
            <td>{{price|currency}}</td>
            <td>{{count}}</td>
        </tr>
      </tbody>
    </table>
</div>

Output:

thing   price   amount
----------------------
widget1 $1.00   10
widget1 $2.00   5
widget2 $4.00   7
widget2 $6.00   6

This would output a tbody per product (thanks to Sebastien C for the great idea). If needed, you can differentiate between the first, middle and last tbody (using ng-repeat's $first, $middle and $last) and style them with ng-class (or even native CSS selectors such as :last-child -- I would recommend ng-class though)

回答3:

Just transform your object to an array... it's pretty easy in JS. Something like:

$scope.data = { 'widget': { '1': 10, '2': 5 } };

var tableData = [];
for (item in $scope.data) {
    var thing = item;
    for (subitem in $scope.data[thing]) {
        tableData.push({
            thing: thing,
            price: subitem,
            amount: $scope.data[thing][subitem]
        });
    }
}

I've created a jsfiddle with this example: http://jsfiddle.net/b7TYf/

回答4:

I used a simple directive which has a recursive function to loop over my nested object and create nested elements. This way you can keep your nested object structure.

Code:

angular.module('nerd').directive('nestedItems', ['$rootScope', '$compile', function($rootScope, $compile) {
    return {
        restrict: 'E',
        scope: false,
        link: function(scope, element, attrs, fn) {

            scope.addElement = function(elem, objAr) {

                var ulElement = angular.element("<ul></ul>");

                if (objAr ==  undefined || objAr.length == 0) {
                    return [];
                }

                objAr.forEach(function(arrayItem) {
                    var newElement = angular.element("<li>"+arrayItem.val+"</li>");
                    ulElement.append(newElement);
                    scope.addElement(newElement,arrayItem.sub);
                });

                elem.append(ulElement);
            };
            
            scope.addElement(element,scope.elements);

        }
    };
}]);

My Object :

$scope.elements = [

      {
          id: 1,
          val: "First Level",
          sub: [

              {
                  id: 2,
                  val: "Second Level - Item 1"
              },
              {
                  id: 3,
                  val: "Second Level - Item 2",
                  sub: [{
                      id: 4,
                      val: "Third Level - Item 1"
                  }]
              }
          ]
      }
  ];

My HTML

<nested-items></nested-items>

来源：https://stackoverflow.com/questions/18330459/ng-repeat-a-single-element-over-nested-objects