从 PostgreSQL 查询生成单个复杂 JSON object

Question

我有一个 PostgreSQL 数据库，其中包含以下表格：

Building

ID	姓名	描述
1	1号楼	第一栋建筑说明
2	2号楼	2楼描述
3	3号楼	3楼描述

Floor

ID	姓名	描述	BUILDING_ID
1	1.1层	楼层说明 1.1	1
2	1.2楼	楼层说明 1.2	1
3	2.1楼	楼层说明 2.1	2
4	2.2楼	楼层说明 2.2	2
5	3.1楼	楼层说明 3.1	3

Room

ID	姓名	描述	FLOOR_ID
1	房间 1.1.1	房间描述 1.1.1	1
2	房间 1.1.2	房间描述 1.1.2	1
3	房间 1.2.1	房间描述 1.2.1	2
4	房间 1.2.2	房间描述 1.2.2	2
5	房间 3.1.1	房间描述 2.1.1	5

生成上述结构的代码可以在这个SQL Fiddle中找到， here 。

我想用一个查询生成一个 JSON object，结构如下：

{
  "Building 1": {
    "details": {
      "id": 1,
      "name": "Building 1",
      "description": "1st Building Description"
    },
    "floors": {
      "Floor 1.1": {
        "details": {
          "id": 1,
          "name": "Floor 1.1",
          "description": "Floor Description 1.1"
        },
        "rooms": {
          "Room 1.1.1": {
            "id": 1,
            "name": "Room 1.1.1",
            "description": "Room Description 1.1.1"
          },
          "Room 1.1.2": {
            "id": 2,
            "name": "Room 1.1.2",
            "description": "Room Description 1.1.2"
          }
        }
      },
      "Floor 1.2": {
        "details": {
          "id": 2,
          "name": "Floor 1.2",
          "description": "Floor Description 1.2"
        },
        "rooms": {
          "Room 1.2.1": {
            "id": "3",
            "name": "Room 1.2.1",
            "description": "Room Description 1.2.1"
          },
          "Room 1.1.2": {
            "id": 4,
            "name": "Room 1.2.2",
            "description": "Room Description 1.2.2"
          }
        }
      },
    }
  },
  
  
  "Building 2": {
    "details": {
      "id": 2,
      "name": "Building 2",
      "description": "2nd Building Description"
    },
    "floors": {
      "Floor 2.1": {
        "details": {
          "id": 3,
          "name": "Floor 2.1",
          "description": "Floor Description 2.1"
        },
        "rooms": {
        }
      },
      "Floor 2.2": {
        "details": {
          "id": 4,
          "name": "Floor 2.2",
          "description": "Floor Description 2.2"
        },
        "rooms": {
        }
      },
    }
  },
  
    
  
  "Building 3": {
    "details": {
      "id": 3,
      "name": "Building 3",
      "description": "3rd Building Description"
    },
    "floors": {
      "Floor 3.1": {
        "details": {
          "id": 5,
          "name": "Floor 3.1",
          "description": "Floor Description 3.1"
        },
        "rooms": {
          "Room 3.1.1": {
            "id": 5,
            "name": "Room 3.1.1",
            "description": "Room Description 3.1.1"
          }
        }
      }
    }
  },
}

解释上面的结构：

1. 需要单个 object output
2. 键始终由对象的名称表示
3. 所有字段都包含在details object
4. 所有子对象都以类似的方式在另一个 object 中展平

不幸的是，我只能使用json_build_object因为上面的结构已经定义了，所以不能更改。

谢谢！

Answer 1

她可以举一个例子来说明你能做什么。 您必须更正并完成此脚本，但我认为它可以完成这项工作

select json_build_object(b.name,json_build_object('details',row_to_json(b),
                        'floors',json_build_object('details',(select json_agg(row_to_json(f))->0 from (select * from floors f where f.building_id = b.id) f)))) 
from buildings b