gogf
util/gconv: After conversion, the interface{} type becomes *interface {}
Go version
go version go1.18 windows/amd64
GoFrame version
v2.7.2
Can this bug be reproduced with the latest release?
Option Yes
What did you do?
package main
import (
"fmt"
"github.com/gogf/gf/v2/util/gconv"
)
func main() {
req := map[string]any{
"id": "123",
"doc": map[string]any{
"craft": nil,
},
"fields": []string{"_id"},
}
var args *UpdateByIdReq
err := gconv.Struct(req, &args)
if err != nil {
panic(err)
}
fmt.Printf("%T", args.Doc["craft"])
}
type UpdateByIdReq struct {
Id string `json:"id" v:"required|length:24,24#id长度错误"`
Doc map[string]interface{} `json:"doc" v:"required"`
Fields []string `json:"fields"`
}
What did you see happen?
输出 *interface {}
What did you expect to see?
应该是 interface{}
package main
import (
"fmt"
"github.com/gogf/gf/v2/util/gconv"
)
func main() {
dataMap := map[string]any{
"doc": map[string]any{
"craft": nil,
},
}
var args *Data
err := gconv.Struct(dataMap, &args)
if err != nil {
panic(err)
}
fmt.Printf("args: %T\n", args.Doc["craft"])
fmt.Printf("dataMap: %T\n", dataMap["doc"].(map[string]any)["craft"])
}
type Data struct {
Doc map[string]interface{} `json:"doc"`
}
Shouldn't your expected output here be nil?
In Go, when you assign nil to a variable of type interface{}, that variable is actually an interface{} pointer to nil. So, when you try to print ARGS. Doc["craft"], it appears as *interface{}, indicating that the value is nil, and the interface{} type holds a pointer to nil.
func main() {
req := map[string]any{
"id": "123",
"doc": map[string]any{
"craft": nil,
},
"fields": []string{"_id"},
}
var args *UpdateByIdReq
err := gconv.Struct(req, &args)
if err != nil {
panic(err)
}
var abc interface{}
abc = nil
fmt.Printf("%T, %T", args.Doc["craft"], abc)
}
output
*interface {}, <nil>
If I check args.Doc["craft"] == nil here, it returns false. Isn't this counterintuitive?
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You should expect the output to be , right?
<nil>
yes
In Go, when you assign nil to a variable of type interface{}, that variable is actually an interface{} pointer to nil. So, when you try to print ARGS. Doc["craft"], it appears as *interface{}, indicating that the value is nil, and the interface{} type holds a pointer to nil.
Thank you. My expected type is <nil>, so that it's easier to make subsequent checks, such as value == nil.