PostgreSql 格式的 jsonb 数组

Question

找不到合适的查询来格式化 postgres 中的 jsonb 输出我在 table.

中有一个 jonb 专栏

Table: Users
id| posts
--------
1 | [{'title': '', 'is_published': '', 'description': '', 'some': 'extra'}, ...]
2 | [{'title': '', 'is_published': '', 'description': '', 'some': 'extra'}, ...]

如何 select 帖子列只包含某些字段？类似于：

id| posts
--------
1 | [{'title':'', 'description': ''}, ...]
2 | [{'title':'', 'description': ''}, ...]

有什么想法吗？

PS: postgres的版本是最新的12,13,14 ...

Answer 1

您可以考虑使用 json_to_record_set 为帖子中的每个数组元素提取所需的列，然后再由用户 id 汇总结果以获得所需的元素。

查询#1

SELECT
    u.id,
    json_agg(
        json_build_object(
            'title',p.title,
            'description',p.description
        )
    ) as posts
FROM
    users u,
    json_to_recordset(u.posts) as p(
          title text,
          is_published text,
          description text,
          some_col text
    )
GROUP BY
    u.id
ORDER BY
    u.id;

id	posts
1	[{"title":"","description":""}]
2	[{"title":"","description":""}]

View on DB Fiddle

或更短

查询 #2

SELECT
    u.id,
    json_agg(p) as posts
FROM
    users u,
    json_to_recordset(u.posts) as p(
          title text,
          description text
    )
GROUP BY
    u.id
ORDER BY
    u.id;

id	posts
1	[{"title":"","description":""}]
2	[{"title":"","description":""}]

View on DB Fiddle

或

查询 #3

SELECT
    u.id,
    (
        SELECT 
            json_agg(p.*) 
        FROM json_to_recordset(u.posts) as p(
             title text,
             description text
        )
      
    ) as posts
FROM
    users u;

View on DB Fiddle

让我知道这是否适合你。

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