I’m trying to find the best way to tackle which I would normally solve with inheritance in a another language, but struggling to find the go way to do it.
I have a number of structs, that all share a common embedded struct. I want to use a common ‘method’ with these structs, and allow them to update a member of the embedded struct.
type EventMetaData struct {
SystemId string `json:"system_id"`
Timestamp string `json:"timestamp"`
}
func (evd *EventMetaData) SetSystemId(systemId string) {
evd.SystemId = systemId
}
type LoginEvent struct {
*EventMetaData
UserId string `json:"user_id"`
Method string `json:"method"`
Timestamp string `json:"timestamp"`
}
type LogoutEvent struct {
*EventMetaData
UserId string `json:"user_id"`
}
type CanSetEventMetaData interface {
SetSystemId(string)
}
func FromPayload(ev *CanSetEventMetaData, payload []byte) (*E, error) {
err := json.Unmarshal(payload, ev)
if err != nil {
return nil, err
}
ev.SetSystemId(config.systemId)
return ev, nil
}
However, the line ev.SetSystemId returns an unresolved reference.
In other languages I’ve used, I’d inherit the base class with the the SetSystemId method. I understand this is not the go way.
>Solution :
What you are doing is correct, however, the parameter ev is a pointer to an interface, it is not an interface. To fix:
func FromPayload(ev CanSetEventMetaData, payload []byte) (*E, error) {
...
}