javascript - 通过比较具有不同键值对的对象对 Javascript 数组进行排序

Question

我正在尝试对波纹管数组进行排序:

var joins = [
  {
    "joinType": "INNER JOIN",
    "joinTableName": "country",
    "joinColumnName": "id",
    "foreignTableName": "state",
    "foreignColumnName": "country_id",
    "index": 1
  },
  {
    "joinType": "INNER JOIN",
    "joinTableName": "state",
    "joinColumnName": "id",
    "foreignTableName": "city",
    "foreignColumnName": "state_id",
    "index": 2
  },
  {
    "joinType": "INNER JOIN",
    "joinTableName": "city",
    "joinColumnName": "id",
    "foreignTableName": "address",
    "foreignColumnName": "city_id",
    "index": 3
  },
  {
    "joinType": "INNER JOIN",
    "joinTableName": "address",
    "joinColumnName": "id",
    "foreignTableName": "user",
    "foreignColumnName": "address_id",
    "index": 4
  },
  {
    "joinType": "INNER JOIN",
    "joinTableName": "user_status",
    "joinColumnName": "id",
    "foreignTableName": "user",
    "foreignColumnName": "status_id",
    "index": 5
  }
]

使用下面的代码:

joins.sort((a, b) => {
  if (a.foreignTableName === b.joinTableName) return 1; //b comes first
  else if (a.joinTableName === b.foreignTableName) return -1; //a comes first
  else return 0; //no change
});

结果是:

[
  {
    "joinType": "INNER JOIN",
    "joinTableName": "state",
    "joinColumnName": "id",
    "foreignTableName": "city",
    "foreignColumnName": "state_id",
    "index": 2
  },
  {
    "joinType": "INNER JOIN",
    "joinTableName": "country",
    "joinColumnName": "id",
    "foreignTableName": "state",
    "foreignColumnName": "country_id",
    "index": 1
  },
  {
    "joinType": "INNER JOIN",
    "joinTableName": "address",
    "joinColumnName": "id",
    "foreignTableName": "user",
    "foreignColumnName": "address_id",
    "index": 4
  },
  {
    "joinType": "INNER JOIN",
    "joinTableName": "city",
    "joinColumnName": "id",
    "foreignTableName": "address",
    "foreignColumnName": "city_id",
    "index": 3
  },
  {
    "joinType": "INNER JOIN",
    "joinTableName": "user_status",
    "joinColumnName": "id",
    "foreignTableName": "user",
    "foreignColumnName": "status_id",
    "index": 5
  }
]

这不是我所期望的——我希望索引为 2 和 1 的元素出现在索引为 3 的元素之后。有什么问题吗？

补充一点，这是从对象字段定义表创建MySql查询语句，该表使用另一个生产系统底层DB的数据来定义业务对象的字段。以上部分用于创建 JOIN 子句。

附言，这是我想要的:

[
  {
    "joinType": "INNER JOIN",
    "joinTableName": "address",
    "joinColumnName": "id",
    "foreignTableName": "user",
    "foreignColumnName": "address_id",
    "index": 4
  },
  {
    "joinType": "INNER JOIN",
    "joinTableName": "city",
    "joinColumnName": "id",
    "foreignTableName": "address",
    "foreignColumnName": "city_id",
    "index": 3
  },
  {
    "joinType": "INNER JOIN",
    "joinTableName": "state",
    "joinColumnName": "id",
    "foreignTableName": "city",
    "foreignColumnName": "state_id",
    "index": 2
  },
  {
    "joinType": "INNER JOIN",
    "joinTableName": "country",
    "joinColumnName": "id",
    "foreignTableName": "state",
    "foreignColumnName": "country_id",
    "index": 1
  },
  {
    "joinType": "INNER JOIN",
    "joinTableName": "user_status",
    "joinColumnName": "id",
    "foreignTableName": "user",
    "foreignColumnName": "status_id",
    "index": 5
  }
]

Answer 1

这里有一种方法，首先为每个对象分配一个 level，该级别由对象的根祖先的 index 和 定义level of deep 对象在它所属的链表中。添加这个新的 lvl 属性后，我们就可以使用这个新属性进行排序了。我不相信这种方法会在性能上如此出色，但也许可以满足您的需求。

var joins = [
  {
    "joinType": "INNER JOIN",
    "joinTableName": "country",
    "joinColumnName": "id",
    "foreignTableName": "state",
    "foreignColumnName": "country_id",
    "index": 1
  },
  {
    "joinType": "INNER JOIN",
    "joinTableName": "state",
    "joinColumnName": "id",
    "foreignTableName": "city",
    "foreignColumnName": "state_id",
    "index": 2
  },
  {
    "joinType": "INNER JOIN",
    "joinTableName": "city",
    "joinColumnName": "id",
    "foreignTableName": "address",
    "foreignColumnName": "city_id",
    "index": 3
  },
  {
    "joinType": "INNER JOIN",
    "joinTableName": "address",
    "joinColumnName": "id",
    "foreignTableName": "user",
    "foreignColumnName": "address_id",
    "index": 4
  },
  {
    "joinType": "INNER JOIN",
    "joinTableName": "user_status",
    "joinColumnName": "id",
    "foreignTableName": "user",
    "foreignColumnName": "status_id",
    "index": 5
  }
];

// Find the object with the table a foreign key is referencing.

const findParent = (fTable) => joins.find(x => x.joinTableName === fTable);

// Recursive method that assigns a level to an object based on the position
// they have on the linked list they belong to.

const getLevel = (fTable, index, lvl) =>
{
    let parent = findParent(fTable);
    return (fTable && parent) ?
           getLevel(parent.foreignTableName, parent.index, lvl + 1) :
           index + "-" + lvl;
}

// Maps the input data to adds the level property to each object.

let newInput = joins.map(obj =>
{
    obj.lvl = getLevel(obj.foreignTableName, obj.index, 0);
    return obj;
});

// Sorts the new generated data based on the level property. Since the
// lvl property is a string, we use "localeCompare()" to compare.

let sortedInput = newInput.sort((a, b) => a.lvl.localeCompare(b.lvl));

// Shows the sorted data.

console.log(sortedInput);