遍历数组以查找具有匹配ID的所有对象，然后将这些对象合并为数组中的一个元素。

Question

I have an array of objects. Some of the objects have identical ids, but different values in certain keys. What I want to do is loop through the array and find all objects with identical ids, and merge them into one object in the array.

My array looks like this:

[{id: 1, letters: [a, b , c] }, {id: 2, letters: [d, e , f] }, {id: 1, letters: [ x, y, z] }]

The outcome I want is an array that looks like this:

[{id: 1, letters: [a, b , c, x, y, z] }, {id: 2, letters: [d, e , f] }] 

I'm using lodash, but just can't quite seem to get it

Answer 1

You can try something like this (that's underscore.js, but I believe lodash is very similar)

data = [{id: 1, letters: ['a', 'b', 'c'] }, {id: 2, letters: ['d', 'e', 'f'] }, {id: 1, letters: ['x', 'y', 'z'] }]

groups = _.groupBy(data, function(obj) { return obj.id })
results = _.map(groups, function(groups) {
  id = groups[0].id;
  letters = _.chain(groups).map(function(obj) { return obj.letters }).flatten().uniq().value()
  return {id: id, letters: letters }
})

console.log(JSON.stringify(results))
// [{"id":1,"letters":["a","b","c","x","y","z"]},{"id":2,"letters":["d","e","f"]}]