[求助]MySQL 存了 json 怎么样才能读出正确的 json 格式？

昨天晚上到今天下午，查了快一天百度也没找到解决办法~人已经崩溃了~ 用的 Gorm 处理~对 Go 也不太熟悉~感觉这搞来搞去真的要高血压了~

首先，我拿到了一个 json ，长这样：

{
    "version": "0.0.1",
    "success": true,
    "result": [
        {
            "service_tag": "12345T",
            "ip_lan": "10.10.10.10",
            "ip_wan": "0.0.0.0",
            "idc": "MH",
            "tags": [
                {
                    "tag_category": "environment",
                    "value": "live"
                },
                {
                    "tag_category": "idc",
                    "value": "sg"
                },
                {
                    "tag_category": "application",
                    "value": "stoc"
                },
                {
                    "tag_category": "function",
                    "value": "redis"
                },
                {
                    "tag_category": "server_standard",
                    "value": "S1"
                },
                {
                    "tag_category": "office",
                    "value": "SG"
                }
            ],
            "memory": "1250GB",
            "cpu_count": 4800,
            "state": "operating"
        }
    ]
}

随后我把 JSON 的 tags 标签存到了 mysql 中，长这样：

[{"tag_category":"environment","value":"live"},{"tag_category":"idc","value":"sg"},{"tag_category":"application","value":"stoc"},{"tag_category":"function","value":"redis"},{"tag_category":"server_standard","value":"S1"},{"tag_category":"office","value":"SG"}]

到这里都没有什么问题，可是我通过 mysql 自带的查询语句查所有数据的时候，查出的并不是 json 格式了~ tags 的内容被当成了字符串，被加了前缀"和后缀",内容中也含有转义字符\

{
    "version": "0.0.1",
    "success": true,
    "result": [
        {
            "ID": 1,
            "ServiceTag": "test",
            "IPLan": "10.10.10.11",
            "IPWan": "0.0.0.0",
            "Idc": "SZ",
            "State": "",
            "Memory": "128GB",
            "CpuCount": 48,
            "Tags": "test",
            "CcUName": "",
            "CcService": "",
            "CreatedAt": 1231,
            "UpdatedAt": 1637956306,
            "PState": "已完成 11111"
        },
        {
            "ID": 2,
            "ServiceTag": "123456T",
            "IPLan": "10.10.10.10",
            "IPWan": "0.0.0.0",
            "Idc": "BJ",
            "State": "operating",
            "Memory": "125GB",
            "CpuCount": 48,
            "Tags": "[{\"tag_category\":\"environment\",\"value\":\"live\"},{\"tag_category\":\"idc\",\"value\":\"sg\"},{\"tag_category\":\"application\",\"value\":\"stoc\"},{\"tag_category\":\"function\",\"value\":\"redis\"},{\"tag_category\":\"server_standard\",\"value\":\"S1\"},{\"tag_category\":\"office\",\"value\":\"SG\"}]",
            "CcName": "",
            "CcService": "",
            "CreatedAt": 1638005233,
            "UpdatedAt": 1638005233,
            "PState": "未解决"
        }
    ]
}

lululau

2021-11-27 20:19:00 +08:00

没有问题

mysql> desc json_demo;
+---------+---------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+---------+---------+------+-----+---------+----------------+
| id | int(11) | NO | PRI | NULL | auto_increment |
| content | json | YES | | NULL | |
+---------+---------+------+-----+---------+----------------+
2 rows in set (0.00 sec)

mysql> insert into json_demo (content) values ('{"title": "test"}');
Query OK, 1 row affected (0.00 sec)

mysql> select * from json_demo;
+----+-------------------+
| id | content |
+----+-------------------+
| 2 | {"title": "test"} |
+----+-------------------+
1 row in set (0.00 sec)

djFFFFF

2021-11-28 13:34:11 +08:00

@szxczyc 有几个点需要确认。
一个是你这张表的 mysql 的字段是什么，是 json 还是 varchar 还是别的
一个是你这个 ServerList 的定义里，gorm 部分的标签是怎么写的。
另一个是，gorm 的 json 字段，如果是自定义类型，都需要实现一个 Scan(value interface{}) error 和一个 Value() (driver.Value, error) 方法，gorm 才能知道如何从 json 转成对应的数据结构。详见 https://gorm.io/docs/data_types.html 这个文档。
举个 map[string]string 的例子：

type SomeJsonField map[string]string

func (i *SomeJsonField) Scan(value interface{}) error {
bytes, _ := value.([]byte)

err := json.Unmarshal(bytes, i)
return err
}

func (i SomeJsonField) Value() (driver.Value, error) {
return json.Marshal(i)
}