英文:
Convert json to struct using reflection in golang
问题
func deserialize(request *http.Request, typ reflect.Type) (interface{}, *httpNet.HandlerError) {
data, e := ioutil.ReadAll(request.Body)
fmt.Println(string(data))
if e != nil {
return nil, &httpNet.HandlerError{e, "无法读取请求", http.StatusBadRequest}
}
v := typ.Elem()
payload := reflect.New(v).Elem().Interface()
eaa := json.NewDecoder(request.Body).Decode(payload)
if e != nil {
fmt.Println(eaa.Error())
}
fmt.Println(payload)
fmt.Println(reflect.ValueOf(payload))
return payload, nil
}
调用它的方式：
r, _ := deserialize(request, reflect.TypeOf(&testData{}))
在我看来，它没有抛出错误，看起来完全有效，但结果是一个期望类型的空结构。
这有什么问题？
英文:
func deserialize(request *http.Request,typ reflect.Type) (interface{}, *httpNet.HandlerError){
data,e:=ioutil.ReadAll(request.Body)
fmt.Println(string(data))
if e !=nil{
return nil,&httpNet.HandlerError{e,"could not read request",http.StatusBadRequest}
}
v:=typ.Elem()
payload:=reflect.New(v).Elem().Interface()
eaa:= json.NewDecoder(request.Body).Decode(payload)
if e!=nil{
fmt.Println(eaa.Error())
}
fmt.Println(payload)
fmt.Println(reflect.ValueOf(payload)
)
return payload,nil
}
to call it:
r,_:= deserialize(request,reflect.TypeOf(&testData{}))
It does not throw errors and looks completely valid operation to me , but the result is an empty structure of expecting type.
Whats the problem with that?
答案1
得分: 4
问题在于你传递了一个非指针类型的实例：
payload := reflect.New(v).Elem().Interface()
这意味着“分配一个指向该类型的新指针，然后取其值，并将其提取为interface{}”。
你应该将其简化为：
payload := reflect.New(v).Interface()
另外，你传递指针类型的类型，然后提取其Elem()，再分配一个指针，这也是多余的。可以像这样做：
if typ.Kind() == reflect.Ptr {
typ = typ.Elem()
}
payload := reflect.New(typ).Interface()
然后你可以将指针和非指针都传递给该函数。
编辑：工作示例：http://play.golang.org/p/TPafxcpIU5
英文:
The problem is that you are passing a non pointer instance of the type:
payload:=reflect.New(v).Elem().Interface()
Means "allocate a new pointer to the type, then take the value of it, and extract it as interface{}.
You should just keep it at:
payload:=reflect.New(v).Interface()
BTW It's also redundant that you are passing the type of a pointer, extracting its Elem(), then allocating a pointer. Do something like this:
if type.Kind() == reflect.Ptr {
typ = typ.Elem()
}
payload := reflect.New(typ).Interface()
then you can pass both pointers and non pointers to the function.
Edit: Working playground example: http://play.golang.org/p/TPafxcpIU5
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