Of course after I ask my question I find the answer on my own.
It's always like this.
The solution is to change
type MessageRequest struct {
Type string `json:"type"`
Payload json.RawMessage `json:"payload"`
}
So the payload isn't unmarshalled.
Now, after the MessageRequest is unmarshalled I can check for the type and
then
payload := new(model.ChatMessage)
if e := json.Unmarshal(m.Payload, payload); e != nil {
logrus.Error(e)
return
}
On Friday, December 14, 2018 at 8:17:25 PM UTC+1, Darko Luketic wrote:
>
> Hello,
>
> I'm sending messages over websocket.
> I have a "generic" MessageRequest and MessageResponse struct.
>
> type MessageRequest struct {
> Type string `json:"type"`
> Payload interface{} `json:"payload"`
> }
>
> type MessageResponse struct {
> Type string `json:"type"`
> Payload interface{} `json:"payload"`
> }
>
>
>
> I'm trying to unmarshall this.
>
> m := new(MessageRequest)
> if e := json.Unmarshal(msg, m); e != nil {
> logrus.Error(e)
> return
> }
>
>
> Then I switch by MessageRequest.Type to know what kind of message was sent
> by the client.
>
> However, when I do something like
> payload, ok := m.Payload.(*MessageRequest)
> if !ok {
> //error
> }
>
> It isn't compatible to type *MessageRequest
> As a workaround I could imagine marshalling the interface again, then
> unmarshalling into the correct message payload type (e.g. ChatMessage)
> But that is unnecessary overhead. However it beats marshalling into
> map[string]interface and manually assigning values in terms of code
> readability.
>
> tmp, e := json.Marshal(m.Payload)
> if e != nil {
> logrus.Error(e)
> return
> }
> payload := new(model.ChatMessage)
> if e := json.Unmarshal(tmp, payload); e != nil {
> logrus.Error(e)
> return
> }
>
>
>
> vs
>
> pmap, ok := m.Payload.(map[string]interface{})
> if !ok {
> logrus.Error("can not convert to map[string]interface{}")
> return
> }
> payload := new(model.ChatMessage)
> user := pmap["user"].(string)
> payload.User = user
>
> message := pmap["message"].(string)
> payload.Message = message
>
> tme := pmap["time"].(string)
> tmee, e := time.Parse(time.RFC3339, tme)
> if e != nil {
> logrus.Error("time parse error")
> return
> }
> payload.Time = tmee
>
>
> Is there a better solution to solve this?
>
>
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