DRY out my Go function with interfaces - interface

Question

I have the following function:
func (r *Resource) Create(kind string, data io.ReadCloser) (err error) {
decoder := json.NewDecoder(data)
r.Kind = kind
switch kind {
case "user":
var user User
if err = decoder.Decode(&user); err != nil {
panic(err)
}
if err = user.Save(r.Context); err != nil {
panic(err)
}
r.Data = user
break
case "space":
var space Space
if err = decoder.Decode(&space); err != nil {
panic(err)
}
if err = space.Save(r.Context); err != nil {
panic(err)
}
r.Data = space
break
case "room":
var room Room
if err = decoder.Decode(&room); err != nil {
panic(err)
}
if err = room.Save(r.Context); err != nil {
panic(err)
}
r.Data = room
break
case "element":
var element Element
if err = decoder.Decode(&element); err != nil {
panic(err)
}
if err = element.Save(r.Context); err != nil {
panic(err)
}
r.Data = element
break
default:
break
}
return
}
As you can see, each case in the switch is identical except for the type of the struct that receives the JSON data.
I suspect that there's an answer in interfaces and type assertion.
EDIT:
I was able to break out the saving part into a separate method, but I still can't figure out a good way to decode the JSON object into the appropriate struct without the switch statement.
func (r *Resource) Create(kind string, data io.ReadCloser) (err error) {
decoder := json.NewDecoder(data)
r.Kind = kind
switch kind {
case "user":
var user User
if err = decoder.Decode(&user); err != nil {
panic(err)
}
r.saveEntity(&user)
break
case "space":
var space Space
if err = decoder.Decode(&space); err != nil {
panic(err)
}
r.saveEntity(&space)
break
case "room":
var room Room
if err = decoder.Decode(&room); err != nil {
panic(err)
}
r.saveEntity(&room)
break
case "element":
var element Element
if err = decoder.Decode(&element); err != nil {
panic(err)
}
r.saveEntity(&element)
break
default:
break
}
return
}
func (r *Resource) saveEntity(e Entity) {
if err := e.Save(r.Context); err != nil {
panic(err)
}
r.Data = e
}

Answer 1

You could move the instantiation to one-line functions and create a mapping which maps the
kind to the respective instantiation function. The rest of the code should be re-usable.
Example:
kinds := map[string]func() Entity {
"user": func() Entity { return &User{} },
"space": func() Entity { return &Space{} },
"room": func() Entity { return &Room{} },
}
func Create(kind string) {
instance := kinds[kind]()
decoder.Decode(instance)
saveEntity(instance)
}