javascript - 根据多个键合并来自两个数组的对象

Question

下面有两个数组，我想根据两个常用键(“iso3”和“year”)合并它们。每个对象必须两者 相同才能合并。数组的长度不同。

array1 = [{
  "id":24006,
  "iso3":"AFG",
  "country":"Afghanistan",
  "year":2014,
  "value":29.78
},
{
  "id":138806,
  "iso3":"ALB",
  "country":"Albania",
  "year":2013,
  "value":0.6341109715
},
{
  "id":44206,
  "iso3":"DZA",
  "country":"Algeria",
  "year":2014,
  "value":39.928947
}]

array2 = [{
  "indicator_id":21806,
  "footnote_id":64811,
  "iso3":"AFG",
  "year":2014
},
{
  "indicator_id":23806,
  "footnote_id":15711,
  "iso3":"AFG",
  "year":2013
},
{
  "indicator_id":123406,
  "footnote_id":15711,
  "iso3":"ALB",
  "year":2013
},
{
  "indicator_id":101606,
  "footnote_id":48911,
  "iso3":"DZA",
  "year":2013
}];

I saw this answer ，但数组仅基于一个公共(public)键合并。我试图从该代码开始工作，但我没有得到任何结果。感谢您的帮助!

Answer 1

另一种利用 sort() 的方法和 reduce() .

JSFiddle example .

代码:

/* Merges two objects into one. You might add some custom logic here,
   if you need to handle some more complex merges, i.e. if the same
   key appears in merged objects in both arrays */
var merge = function(o1, o2) {
  var result = {};
  for (var a in o1) { result[a] = o1[a]; }
  for (var a in o2) { result[a] = o2[a]; }
  return result;
}

/* Returns 0 if two objects are equal, -1 if first one is 'lower',
   and 1 if it's 'larger'. It's used to sort the arrays. Objects are
   compared using iso3 and year properties only. */
var compareByIsoAndYear = function (o1, o2) {
  if (o1.iso3 === o2.iso3 && o1.year === o2.year) return 0
  else if (o1.year > o2.year) return 1
  else if (o1.year < o2.year) return -1
  else if (o1.iso3 > o2.iso3) return 1;
}

/* Used in reduce */
var mergeTwoObjects = function(initial, current) {
  if (initial.length > 0) {
    var last = initial[initial.length-1];
    if (compareByIsoAndYear(last, current) === 0) {
      initial[initial.length-1] = merge(last, current);
      return initial;
    }
  }
  initial.push(current);
  return initial;
}

/* Take both arrays and concatenate them into one. Then sort them,
   to make sure that objects with the same year and iso3 would appear
   next to each other, and then merge them if needed */
var result = array1.concat(array2)
                   .sort(compareByIsoAndYear)
                   .reduce(mergeTwoObjects, []);

结果:

[{
  "indicator_id": 23806,      /* Found in array2 only, not merged */
  "footnote_id": 15711,
  "iso3": "AFG",
  "year": 2013
}, {
  "id": 138806,               /* This one has been merged */
  "iso3": "ALB",
  "country": "Albania",
  "year": 2013,
  "value": 0.6341109715,
  "indicator_id": 123406,
  "footnote_id": 15711
}, {           
  "indicator_id": 101606,     /* Found in array2 only, not merged */
  "footnote_id": 48911,
  "iso3": "DZA",
  "year": 2013
}, {
  "id": 24006,                /* This one has been merged */
  "iso3": "AFG",
  "country": "Afghanistan",
  "year": 2014,
  "value": 29.78,
  "indicator_id": 21806,
  "footnote_id": 64811
}, {
  "id": 44206,                /* Found in array1 only, not merged */
  "iso3": "DZA",
  "country": "Algeria",
  "year": 2014,
  "value": 39.928947
}]