Lodash 和 Arrays 与 Key 的合并答案

【问题标题】：Lodash and merge of Arrays with KeyLodash 和 Arrays 与 Key 的合并
【发布时间】：2019-04-30 00:15:57
【问题描述】：

我可以使用 lodash 很好地合并存储在数组中的对象，但我需要的是找到一种基于作为对象一部分的键进行合并的方法。如果我不使用密钥，则合并不可靠，因为当文档无序返回时，它将创建无效的合并。所以我希望有一种基于键值合并的方法，在我的例子中是它的 id。

这是一些示例：

文件 1

[
    {
         "id": 123,
         "Key1": "Test 1",
         "Key3": "Test 0"
    },
    {
         "id": 456,
         "Key1": "Test 2",
         "Key2": "Test 3"
    }
]

文件 2

[

    {
         "id": 123,
         "Key2": "Test 7",
         "Key3": "Test 8"
    },
    {
         "id": 789,
         "Key1": "Test 5",
         "Key2": "Test 6"
    }
]

根据上面的简单示例，我正在寻找这样的输出

[
    {
         "id": 123,
         "Key1": "Test 1",
         "Key2": "Test 7",
         "Key3": "Test 8"
    },
    {
         "id": 456,
         "Key1": "Test 2",
         "Key2": "Test 3"
    },
    {
         "id": 789,
         "Key1": "Test 5",
         "Key2": "Test 6"
    }
]

【问题讨论】：

标签： lodash

【解决方案1】：

const addKeys = (results, keys) => keys.reduce(
  (final, item) => {
    const id = item.id;
    let current = final.find(i => i.id === id);
    if (!current) {
      current = { id: id };
      final.push(current);
    }
    Object.keys(item).forEach(key => { current[key] = item[key] });
    return final;
  }, results
);

console.log(addKeys(
  [
      {
           "id": 123,
           "Key1": "Test 1",
           "Key3": "Test 0"
      },
      {
           "id": 456,
           "Key1": "Test 2",
           "Key2": "Test 3"
      }
  ],
  [

      {
           "id": 123,
           "Key2": "Test 7",
           "Key3": "Test 8"
      },
      {
           "id": 789,
           "Key1": "Test 5",
           "Key2": "Test 6"
      }
  ]
));

【讨论】：

就像一个魅力，不知道为什么有人反对这个答案

【解决方案2】：

使用流创建函数。将数组连接到单个数组，按id 分组，然后映射组，并将每个组合并到单个对象：

const { flow, concat, partialRight: pr, groupBy, map, merge } = _

const mergeArrays = flow(
  concat, // concat to a single array
  pr(groupBy, 'id'), // group item by id
  pr(map, g => merge({}, ...g)) // merge each group to a single object
)

const arr1 = [{"id":123,"Key1":"Test 1","Key3":"Test 0"},{"id":456,"Key1":"Test 2","Key2":"Test 3"}]
const arr2 = [{"id":123,"Key2":"Test 7","Key3":"Test 8"},{"id":789,"Key1":"Test 5","Key2":"Test 6"}]

const result = mergeArrays(arr1, arr2)

console.log(result)

&lt;script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.11/lodash.js"&gt;&lt;/script&gt;

这个解决方案的简洁版本带有lodash/fp：

const { flow, concat, groupBy, map, mergeAll } = _

const mergeArrays = flow(
  concat, // concat to a single array
  groupBy('id'), // group item by id
  map(mergeAll) // merge each group to a single object
)

const arr1 = [{"id":123,"Key1":"Test 1","Key3":"Test 0"},{"id":456,"Key1":"Test 2","Key2":"Test 3"}]
const arr2 = [{"id":123,"Key2":"Test 7","Key3":"Test 8"},{"id":789,"Key1":"Test 5","Key2":"Test 6"}]

const result = mergeArrays(arr1, arr2)

console.log(result)

&lt;script src='https://cdn.jsdelivr.net/g/lodash@4(lodash.min.js+lodash.fp.min.js)'&gt;&lt;/script&gt;

【讨论】：