underscore.js 的 groupBy 对象数组

Question

我有一个对象数组 (order) (products): ，我想按 id 对所有这些产品进行分组和计数:

var order = [
{ product_id: 70, product_price: 9, product_color: "ccc"},
{ product_id: 70, product_price: 9, product_color: "ccc"},
{ product_id: 71, product_price: 10, product_color: "fff" } ];

与 Underscore.js:

var groups = _.countBy(order, function(value){
    return value.product_id + "#" + value.product_price + "#" + value.product_color;
})
//--> Object {70#ccc#9: 2, 71#fff#10: 1}

所以它有效……但是现在，我如何才能 return 将这些值放入这样的数组中，以便我可以将其用作新的对象数组？

 [
    { product_id: 70, product_price: 9, product_color: "ccc", count: 2},
    { product_id: 70, product_price: 9, product_color: "fff", count: 1}
 ];

Answer 1

您可以跨组使用 groupBy and then map 来添加计数，而不是 countBy：

var groups = _.groupBy(order, function(value){
    return value.product_id + "#" + value.product_price + "#" + value.product_color;
})

groups = _.map(groups, function(group){
    return _.extend(group[0], {count: group.length});
});

Answer 2

您可以使用 reduce 重新创建原始数组。

var countedById = [
    { product_id: 70, product_price: 9, product_color: "ccc", count: 2},
    { product_id: 70, product_price: 9, product_color: "fff", count: 1}
 ];

var original = countedById.reduce((acc, cur) => {
  for (var i = 0; i < cur.count; i++) {
    var original = {
      product_id: cur.product_id,
      product_price: cur.product_price,
      product_color: cur.product_color
    }
    acc.push(original);
  }
  return acc;
  }, []);

document.write(JSON.stringify(original))

underscore.js 的 groupBy 对象数组

groupBy array of objects with underscore.js

javascript

jquery

underscore.js