Comments (6)
问题出在这里:
type App struct {
ModelMeta // 这里你也需要定义tag `ddb:"you name it"`
Project string `json:"project" ddb:"project"`
Name string `json:"name" ddb:"name"`
}
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这个本身app的数据体是类似这样的:
{
id: 1,
ctime: "2019-07-24T16:03:39+08:00",
mtime: "2019-07-24T16:03:39+08:00",
project: "xxx",
name: "xxx"
}
ModelMeta如果定义tag的话,岂不是多了一层
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因为你的某个字段如果没定义ddb的tag,gendry就会认为那个字段和表数据无关,所以你的结构体定义必须跟表结构保持一致:
type App struct {
ID int `ddb:"id"`
CTime time.TIme `ddb:"ctime"`
// ...
Project string `json:"project" ddb:"project"`
Name string `json:"name" ddb:"name"`
}
然后再根据需要把能和表结构映射上的对象,转换成你逻辑上需要的对象。
嵌套结构体一般上只适用于字段值是json的情况,比如你在表里把学生考试成绩类型设置为json,或者类型就是varchar但里面存的是json字符串:
{
"name": "tom",
"exam_result": {"math": 100, "chinese": 98}
}
这时候你就可以通过定义嵌套结构体来Scan,如果某个字段类型是pb的二进制,你也可以自己实现ByteUnmarshaler
接口来自定义怎么Unmarshal
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Go里面的embedded struct
,个人理解应该字段就是继承自源结构体了,常见的ORM,比如beego实现的ORM,也是支持这样的嵌套结构体的数据序列化反序列化的,是否可以考虑支持这样的场景?
这个可能跟显式的某个字段是JSON\PB的情况还不太一样,它其实就是app的一组字段,不是多加了一层的JSON
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如果要支持自动绑定embedded struct,那下面这样的结构体也要支持:
// {"id": 1, "col_e": 20}
type Table struct {
ID int `ddb:"id"`
A struct {
B struct {
C struct {
D struct {
E int `ddb:"col_e"`
}
}
}
}
}
我个人感觉这个实际上还是对象功能职责没有分清楚。表结构本身就是col_a=1&col_b=2这样的kv集合。实际中我还是推荐,针对每个表专门写一个与其对应的结构体。Scan操作的都是这类结构体。之后,你可以进行各种领域建模和抽象,这个结构体中哪几个字段属于UserInfo,哪些属于MetaData,然后再定义对应的结构体把表数据转换成你期望的对象。这样或许稍微有点麻烦,但是结构很清晰。
至于为每个表专门写对应的结构体,其实有工具可以根据你的数据库自动生成,你可以看看文档最后的链接
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soga!感谢大佬指点!
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Related Issues (20)
- 是否支持MySQL关键词 HOT 2
- scanner.Scan返回错误码 HOT 3
- buildDelete不支持limit操作 HOT 1
- 请问下, BuildInsertOnDuplicate方法支持如下的sql吗? HOT 3
- 支持force index操作吗
- "[scanner]: empty result" HOT 4
- 请问可以支持UNION ALL语句吗? HOT 1
- 支持多个 or 查询 HOT 1
- scanner在go继承模式下,无法scan到父级tag HOT 1
- 请求打个最新版本的tag HOT 1
- mysql传limit句柄错误 HOT 9
- 您好,支持 IS NOT NULL吗?在文档里没有看到 HOT 2
- 对rows进行scan后, 需要检查err
- scan不支持结构体嵌套赋值
- where语句中两列数据相互比较,如何正确声明查询条件呢? HOT 5
- scan 对于继承的struct不生效 HOT 1
- ctx超时或取消情况下,scanner.Scan()方法会把err吞掉,不返回err,导致读出的数据不全
- map[string]interface{} support between ? and ? HOT 2
- buildInsert 对于mysql 5.7升级mysql 8.0 , 用到mysql 8.0关键词的人不友好, HOT 15
- [proposal] Support _custom HOT 1
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