在 Lodash 中合并（内部连接）仅保留具有公共键的行

Question

尝试使用 lodash 合并两个 API 的 return，我设法使用合并将它们中的公共字段连接起来：

var primaryCount = [
    {id: 0, name: "foo", address: "one"},
    {id: 1, name: "bar", address: "two"},
];
var secondaryCount = [
    {franchise_id: 1, count:4},
  {franchise_id: 3, count:16},
]

var merged = _.merge(_.keyBy(primaryCount, 'id'), _.keyBy(secondaryCount, 'franchise_id'));
var values = _.values(merged);

但是我只需要定义了 id 和 franchise_id 字段的项目。但是它产生的字段只存在于其中一个字段中（我只想要 id:1）：

[
   {
      "id": 0,
      "name": "foo",
      "address": "one"
   },
   {
      "id": 1,
      "name": "bar",
      "address": "two",
      "franchise_id": 1,
      "count": 4
   },
   {
      "franchise_id": 3,
      "count": 16
   }
]

我试过像这样使用过滤器，但它 return 两者都是一个空数组：

var leftFiltered = _.filter(values, ['id', null]);
var rightFiltered = _.filter(leftFiltered, ['franchise_id', undefined]);

如何进行这样的内部合并？

[
   {
      "id": 1,
      "name": "bar",
      "address": "two",
      "franchise_id": 1,
      "count": 4
   },
]

Answer 1

您可以创建自定义过滤和映射逻辑或使用 lodash-joins

#### Example:
> var _ = require('index.js');
> var left = [
...       {id: 'c', left: 0},
...       {id: 'c', left: 1},
...       {id: 'e', left: 2},
...   ],
...   right = [
...       {id: 'a', right: 0},
...       {id: 'b', right: 1},
...       {id: 'c', right: 2},
...       {id: 'c', right: 3},
...       {id: 'd', right: 4},
...       {id: 'f', right: 5},
...       {id: 'g', right: 6}
...   ],
...   accessor = function (obj) {
...       return obj['id'];
...   };
>
> var a = _.hashInnerJoin(left, accessor, right, accessor);
undefined
> a
[ { id: 'c', left: 0, right: 2 },
  { id: 'c', left: 1, right: 2 },
  { id: 'c', left: 0, right: 3 },
  { id: 'c', left: 1, right: 3 } ]
>
> var b = _.nestedLoopLeftOuterJoin(left, accessor, right, accessor);
undefined
> b
[ { id: 'c', left: 0, right: 2 },
  { id: 'c', left: 0, right: 3 },
  { id: 'c', left: 1, right: 2 },
  { id: 'c', left: 1, right: 3 },
  { id: 'e', left: 2 } ]
>
> var c = _.sortedMergeFullOuterJoin(left, accessor, right, accessor);
undefined
> c
[ { id: 'a', right: 0 },
  { id: 'b', right: 1 },
  { id: 'c', left: 0, right: 2 },
  { id: 'c', left: 0, right: 3 },
  { id: 'c', left: 1, right: 2 },
  { id: 'c', left: 1, right: 3 },
  { id: 'd', right: 4 },
  { id: 'e', left: 2 },
  { id: 'f', right: 5 },
  { id: 'g', right: 6 } ]

在 Lodash 中合并（内部连接）仅保留具有公共键的行

Merge (inner join) in Lodash keeping only rows with common keys

javascript

merge

filtering

lodash