MySQL将json对象附加到json对象数组

Question

在此表中- foo_table我有一列- foo_ids其内容如下：
[{"id": "432"}, {"id": "433"}]

我的问题是否有办法将新的json对象附加到此列？所以例如，如果我有这个新对象- {"id": "554"}我希望我的foo_ids列值成为-
[{"id": "432"}, {"id": "433"}, {"id": "554"}]
任何想法，如果不存在，如何插入，如果已经存在，追加新的json对象？

Answer 1

您可以使用JSON_ARRAY_APPEND如下功能：

mysql> SELECT VERSION();
+-----------+
| VERSION() |
+-----------+
| 5.7.19    |
+-----------+
1 row in set (0.00 sec)

mysql> DROP TABLE IF EXISTS `foo_table`;
Query OK, 0 rows affected (0.00 sec)

mysql> CREATE TABLE IF NOT EXISTS `foo_table` (
    ->   `id` SERIAL,
    ->   `foo_ids` JSON
    -> );
Query OK, 0 rows affected (0.01 sec)

mysql> INSERT INTO `foo_table` (`foo_ids`)
    -> VALUES (NULL);
Query OK, 1 row affected (0.00 sec)

mysql> SELECT `id`, `foo_ids`
    -> FROM `foo_table`;
+----+---------+
| id | foo_ids |
+----+---------+
|  1 | NULL    |
+----+---------+
1 row in set (0.00 sec)

mysql> UPDATE `foo_table`
    -> SET `foo_ids` = IF(
    ->                     `foo_ids` IS NULL OR
    ->                     JSON_TYPE(`foo_ids`) != 'ARRAY',
    ->                     JSON_ARRAY(),
    ->                     `foo_ids`
    ->                   ),
    ->     `foo_ids` = JSON_ARRAY_APPEND(
    ->                   `foo_ids`,
    ->                   '$',
    ->                   CAST('{"id": "432"}' AS JSON),
    ->                   '$',
    ->                   CAST('{"id": "433"}' AS JSON)
    ->                 )
    -> WHERE `id` = 1;
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0

mysql> SELECT `id`, `foo_ids`
    -> FROM `foo_table`;
+----+--------------------------------+
| id | foo_ids                        |
+----+--------------------------------+
|  1 | [{"id": "432"}, {"id": "433"}] |
+----+--------------------------------+
1 row in set (0.00 sec)

mysql> UPDATE `foo_table`
    -> SET `foo_ids` = IF(
    ->                     `foo_ids` IS NULL OR
    ->                     JSON_TYPE(`foo_ids`) != 'ARRAY',
    ->                     JSON_ARRAY(),
    ->                     `foo_ids`
    ->                   ),
    ->     `foo_ids` = JSON_ARRAY_APPEND(
    ->                   `foo_ids`,
    ->                   '$',
    ->                   CAST('{"id": "554"}' AS JSON)
    ->                 )
    -> WHERE `id` = 1;
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0

mysql> SELECT `id`, `foo_ids`
    -> FROM `foo_table`;
+----+-----------------------------------------------+
| id | foo_ids                                       |
+----+-----------------------------------------------+
|  1 | [{"id": "432"}, {"id": "433"}, {"id": "554"}] |
+----+-----------------------------------------------+
1 row in set (0.00 sec)

参见db-fiddle。

更新

也可以<=>在条件上使用运算符：

mysql> UPDATE `foo_table`
    -> SET `foo_ids` = IF(
    ->                     JSON_TYPE(`foo_ids`) <=> 'ARRAY',
    ->                     `foo_ids`,
    ->                     JSON_ARRAY()
    ->                   ),
    ->     `foo_ids` = JSON_ARRAY_APPEND(
    ->                   `foo_ids`,
    ->                   '$',
    ->                   CAST('{"id": "554"}' AS JSON)
    ->                 )
    -> WHERE `id` = 1;
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0

参见db-fiddle。