I try to write simple message protocol in go and i've encountered a problem. I have a lot of message types and i want to have a dictionary like this to manipulate with messages:
var dict map[reflect.Type]int = map[reflect.Type]int{
reflect.TypeOf(DataMessage{}): 1000,
reflect.TypeOf(TextMessage{}): 1001,
//....
}
func GetMessageTypeId(value interface{}) int {
if id, ok := dict[reflect.TypeOf(value)]; ok {
return id
} else {
return -1
}
}
func GetValueByTypeId(typeId int) interface{} {
for typeDec, id := range dict {
if id == typeId {
return reflect.Zero(typeDec).Interface()
}
}
fmt.Println("Unknown message type", typeId)
return nil
}
It works fine, but when i instantiate message with GetValueByTypeId and try to unmarshall json into it - i receive map[string]interface instead of my message. I've made simple example to reproduce the problem: