英文:
golang: How to check for exported fields in an interface
问题
import (
"fmt"
"reflect"
)
type StatusVal int
type Foo struct {
Name string
Age int
art string
}
func ListFields(a interface{}) {
v := reflect.ValueOf(a).Elem()
fmt.Printf(" Kind: %+v \n", v.Type())
for _, f := range reflect.VisibleFields(v.Type()) {
if f.IsExported() {
fmt.Printf(" Kind: %+v \n", f)
} else {
fmt.Printf(" Kind: %s \n", f.Name)
}
}
}
func main() {
var x Foo
ListFields(&x)
}
这段代码是可以工作的，但我真正需要的是 var x []Foo ，我找不到方法来实现并检查结构体切片中的字段是否为导出字段。
长版本：
我想要生成一个通用的 sqlToStruct 函数，然后我遇到了这个很棒的答案：
https://stackoverflow.com/questions/62240553/generalizing-sql-rows-scan-in-go/62240694#62240694
我没有足够的声望在那里回复。
唯一的问题是，如果我的结构体有任何未导出的字段，它会引发 panic，我希望能够检查并返回一个错误供处理，而不是让它 panic。
另外：我在 Go 中编程的时间非常短，请理解我现在的情况，如果我漏掉了一些非常明显的东西，请原谅。
英文:
short version:
import (
"fmt"
"reflect"
)
type StatusVal int
type Foo struct {
Name string
Age int
art string
}
func ListFields(a interface{}) {
v := reflect.ValueOf(a).Elem()
fmt.Printf(" Kind: %+v \n", v.Type())
for _, f := range reflect.VisibleFields(v.Type()) {
if f.IsExported() {
fmt.Printf(" Kind: %+v \n", f)
} else {
fmt.Printf(" Kind: %s \n", f.Name)
}
}
}
func main() {
var x Foo
ListFields(&x)
}
This code works, but what I really need is var x []Foo , and I cannot find a way to get that to work and check for IsExported in the fields of the slice of structs.
Long version:
I was looking to generate a generic sqlToStruct function, and I bumped into this awesome answer:
https://stackoverflow.com/questions/62240553/generalizing-sql-rows-scan-in-go/62240694#62240694
I don't have the reputation to reply there.
The only problem with that is that if my struct has any unexported fields, it panics, and I would like to check for that and return an error to be handled, rather than let it panic.
Also: I have been coding in go for a very short amount of time, please understand where I am coming from and sorry if I am missing something absolutely obvious.
答案1
得分: 1
func ListFields(a interface{}) {
rt := reflect.TypeOf(a) // 获取a的类型
if rt.Kind() == reflect.Ptr {
rt = rt.Elem() // 使用Elem获取指向的类型
}
if rt.Kind() == reflect.Slice {
rt = rt.Elem() // 使用Elem获取切片元素的类型
}
if rt.Kind() == reflect.Ptr { // 处理类似 []*StructType 的输入类型
rt = rt.Elem() // 使用Elem获取指向的类型
}
if rt.Kind() != reflect.Struct {
return
}
fmt.Printf("类型: %+v \n", rt)
for _, f := range reflect.VisibleFields(rt) {
if f.IsExported() {
fmt.Printf("类型: %+v \n", f)
} else {
fmt.Printf("类型: %s \n", f.Name)
}
}
}
https://go.dev/play/p/0J3VXmFPe87
英文:
func ListFields(a interface{}) {
rt := reflect.TypeOf(a) // take type of a
if rt.Kind() == reflect.Ptr {
rt = rt.Elem() // use Elem to get the pointed-to-type
}
if rt.Kind() == reflect.Slice {
rt = rt.Elem() // use Elem to get type of slice's element
}
if rt.Kind() == reflect.Ptr { // handle input of type like []*StructType
rt = rt.Elem() // use Elem to get the pointed-to-type
}
if rt.Kind() != reflect.Struct {
return
}
fmt.Printf(" Kind: %+v \n", rt)
for _, f := range reflect.VisibleFields(rt) {
if f.IsExported() {
fmt.Printf(" Kind: %+v \n", f)
} else {
fmt.Printf(" Kind: %s \n", f.Name)
}
}
}
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