fix(database/gdb): json type field incorrect scanning to slice attribute #4107
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@gqcn You can use pr #4114 for such problems in the future. You don’t need to modify gf every time you encounter a type that is not supported. Just open the interface for custom type conversion. ORM only supports some common types by default. |
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这次改动挺大的啊，使用方法有啥调整吗 |
This time the change is quite big. Are there any adjustments to the usage method? |
主要是为了解耦设计，之前这个converter的实现是放外层的，但是容易出现循环依赖。比如在converter的实现中调用了String方法，String方法内部又调用了defaultConverter。放独立的包容易解耦。 |
It is mainly designed for decoupling. The previous implementation of this converter was placed on the outer layer, but it is prone to circular dependencies. For example, the String method is called in the converter implementation, and the defaultConverter is called inside the String method. It is easy to decouple if placed in an independent package. |
那不应该啊，现在把所有的逻辑都移到converter类型上，直接从这个类型调用就行了，为什么还要去调用外部的String方法， |
That shouldn't be. Now move all the logic to the converter type and just call it from this type. Why do you still need to call the external String method? |
是得，作为独立包就可以完全避免这样的问题了。放一起的话，很难避免，容易出错。 |
Yes, as an independent package, you can completely avoid such problems. If put together, it is difficult to avoid and makes mistakes easily. |
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@gqcn 目前还存在一些问题 func anyToMyInt(from any, to reflect.Value) error {
switch x := from.(type) {
case int:
println("x=", x)
to.SetInt(123456)
default:
return fmt.Errorf("unsupported type %T(%v)", from, from)
}
return nil
}
// 1. 注册为指针类型时，此时自定义转换不生效
conv1 := gconv.NewConverter()
conv1.RegisterAnyConverterFunc(anyToMyInt, reflect.TypeOf((*myInt)(nil)))
var dst struct {
A myInt
B myInt
}
err := conv1.Struct(map[string]any{
"a": 1200,
"b": 2400,
}, &dst, gconv.StructOption{})
// dst = {1200, 2400}
//2. 注册为值类型，自定义转换会生效
conv2 := gconv.NewConverter()
conv2 .RegisterAnyConverterFunc(anyToMyInt, reflect.TypeOf((myInt)(0)))
var dst struct {
A *myInt
B *myInt
}
err := conv2 .Struct(map[string]any{
"a": 1200,
"b": 2400,
}, &dst, gconv.StructOption{})
// dst = {123456, 123456}
|
嗯，可以提个pr合并到这个分支一起完善下，我这边最近在准备 |
2.实例化CachedStructInfo时，直接传入Converter 3.增强(*CachedStructInfo).genFieldConvertFunc的逻辑
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@gqcn 关于对RegisterAnyConverterFunc的说明，后续可以放在注释和文档中 RegisterAnyConverterFunc分为非接口注册和接口注册1.非接口类型注册这个比较好理解，就是注册了一个具体类型的转换函数 2.接口类型注册当注册的类型为接口类型时，并不是目标类型为接口类型时才有效而是指实现了接口类型 需要注意的是，当你注册了空接口类型，相当于注册了所有类型，因为所有类型都实现了空接口 假如同时注册了sql.NullInt64和sql.Scanner，那么只有sql.NullInt64会生效，因为它的优先级比较高 举例说明// 注册sql.Scanner接口
RegisterAnyConverterFunc(anyToSqlNullType,reflect.TypeOf((*sql.Scanner)(nil)))
// 转换函数
func anyToSqlNullType(from any,to reflect.Value)error{
if to.Kind()!=reflect.Ptr {
to = to.Addr()
}
// 只要经过此函数，都赋值为123456
return to.Interface().(*sql.Scanner).Scan(123456)
}
// 假设我们要转换的结构体类型
// 因为A,B,C,D四个字段的类型均实现了sql.Scanner接口，
// 所以转换的时候，都会经过anyToSqlNullType函数的逻辑
// 但是E字段并不会经过anyToSqlNullType函数
type sqlNullDst struct {
A sql.Null[int]
B sql.Null[float32]
C sql.NullInt64
D sql.NullString
E sql.Scanner
}
var dst sqlNullDst
gconv.Struct(map[string]any{
"a": 12,
"b": 34,
"c": 56,
"d": "sqlNullString",
// 如果这样写会报错：reflect.Value.Convert: value of type string cannot be converted to type sql.Scanner
"e":"sql.Scanner"
// 下面的可以正常通过
// "e":&sql.NullString{String: "123456", Valid: true}
}, &dst)
// 由于经过anyToSqlNullType函数，所以dst的四个字段的值也都为123456
// 并不是a=12，b=34 |
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