将分组查询转换为对象树

Question

我想在js中将查询的结果转化为树对象，查询的每个字段都被添加到js文件中的数组中，如['field2', 'field3']，所以后端创建动态用它查询，必须从左到右从最外部到最内部字段创建树（查询也按字段的 id 分组），这就是查询（记住，字段是动态的，因此添加了更多字段)，树的最后一个分支应该是数量（也是动态的）

SELECT 
    T2.field2 as field2, T3.field3 as field3, SUM(quantity) AS quantity
FROM 
    table1 T1
    INNER JOIN
    table2 T2 ON T1.table2_id = T2.id
    INNER JOIN
    table3 T3 ON T1.table3_id = T3.id
WHERE
    AND T1.date = 20190611
GROUP BY T1.table2_id, T1.table3_id

这将给我一组这样的数据

'Group 1', 'Data 0', '9172'
'Group 1', 'Data 1', '789'
'Group 1', 'Data 22', '289'
'Group 1', 'Data 3', '254'
'Group 1', 'Data 4', '197'
'Group 1', 'Data 55', '173'
'Group 2', 'Data 0', '38'
'Group 2', 'Data 11', '3'
'Group 2', 'Data 4', '4'
'Group 3', 'Data 0', '807'
'Group 3', 'Data 1', '40'
'Group 3', 'Data 18', '4'
'Group 3', 'Data 2', '35'

我需要做的就是把它变成这样的东西。

[
  {
    field2: 'Group 1',
    data: [
      {
        field3: 'Data 0',
        data: [
          { quatity: 9172 },
        ],
      },
      {
        field3: 'Data 1',
        data: [
          { quatity: 789 },
        ],
      },
      {
        field3: 'Data 3',
        data: [
          { quatity: 289 },
        ],
      },
      {
        field3: 'Data 4',
        data: [
          { quatity: 197 },
        ],
      },
      {
        field3: 'Data 55',
        data: [
          { quatity: 173 },
        ],
      },
    ],
  },
  {
    field2: 'Group 2',
    data: [
      {
        field3: 'Data 0',
        data: [
          { quatity: 38 },
        ],
      },
      {
        field3: 'Data 11',
        data: [
          { quatity: 3 },
        ],
      },
      {
        field3: 'Data 4',
        data: [
          { quatity: 4 },
        ],
      },
    ],
  },
  {
    field2: 'Group 3',
    data: [
      {
        field3: 'Data 0',
        data: [
          { quatity: 807 },
        ],
      },
      {
        field3: 'Data 1',
        data: [
          { quatity: 40 },
        ],
      },
      {
        field3: 'Data 18',
        data: [
          { quatity: 4 },
        ],
      },
      {
        field3: 'Data 2',
        data: [
          { quatity: 35 },
        ],
      },
    ],
  },
]

这里的技巧是查询中的字段是动态的，所以我需要继续查找直到它到达列表中的最后一个字段，所以如果字段数组有 ['field2', 'field3', 'field4'] 和数组之类的项目的值有一个像 ['quantity', 'balance'] 这样的数组结果应该类似于

[
  {
    field2: 'Group 1',
    data: [
      {
        field3: 'Data 0',
        data: [
          {
            field4: 'Last field,
            data: [
              { quantity: 3435, balance: 43.53 },
            ],
          },
          {
            field4: 'Last field,
            data: [
              { quantity: 234, balance: 241.53 },
            ],
          },
        ],
      },
    ],
  },
]

如何做到这一点？

Answer 1

您可以采用组合方法，使用键和值数组并查找相同的对象。

var data = [['Group 1', 'Data 0', '9172'], ['Group 1', 'Data 1', '789'], ['Group 1', 'Data 22', '289'], ['Group 1', 'Data 3', '254'], ['Group 1', 'Data 4', '197'], ['Group 1', 'Data 55', '173'], ['Group 2', 'Data 0', '38'], ['Group 2', 'Data 11', '3'], ['Group 2', 'Data 4', '4'], ['Group 3', 'Data 0', '807'], ['Group 3', 'Data 1', '40'], ['Group 3', 'Data 18', '4'], ['Group 3', 'Data 2', '35']],
    keys = ['field2', 'field3'],
    values = ['quantity'],
    result = data.reduce((r, a) => {
        keys
            .reduce((q, k, i) => {
                var temp = q.find(o => o[k] === a[i]);
                if (!temp) q.push(temp = { [k]: a[i], data: [] });
                return temp.data;
            }, r)
            .push(Object.assign({}, ...values.map((k, i) => ({ [k]: a[keys.length + i] }))));
        return r;
    }, []);

console.log(result);

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