Gin MarshalJSON not being called

With the given code below, it seems like the custom MarshalJSON function isn't being called with i hit the api endpoint. Should it be?

type User struct {
 FirstName string `json:"first"`
 LastName string `json:"last"`
 Fullname string `json:"full"`
}

func (u *User) MarshalJSON() ([]byte, error) {
    type Alias User
    return json.Marshal(&struct {
        FullName string `json:"full"`
        *Alias
    }{
        FullName: fmt.Sprintf("%s %s", u.FirstName, u.LastName),
        Alias:  (*Alias)(u),
    })
}

......

user := User{
  FirstName: "Bob",
 LastName: "Denver",
}

c.JSON(200, user)

I am not seeing the full name attribute filed out like i'd expect. Any thoughts on what i may be missing here?

Comment From: cbarraford

I've been able to limit the issue to be something outside of gin, so closing ticket.

Comment From: mjip

What was the fix you ended up finding?

Comment From: cbarraford

sorry i don't remember

Comment From: DDevine

The issue seems to be satisfying the interface on *User rather than User. Notice the small difference.

Try something like this:

func (u User) MarshalJSON() ([]byte, error) {
    type Alias User
    return json.Marshal(&struct {
        FullName string `json:"full"`
        *Alias
    }{
        FullName: fmt.Sprintf("%s %s", u.FirstName, u.LastName),
        Alias:  (*Alias)(&u),
    })
}

I'm very new to Go, so if this is not helpful for some reason please let me know because I don't want to mislead anybody. Having said that - I've tried it and it works for me!

Comment From: archiewx

@DDevine nice! When using the *User, only ptr can be called.

Comment From: YannikHinteregger

Omg, thanks! Finding this took me 2 days.