JSON unmarshal integer field into a string

Question

I am struggling with deserializing a integer into a string struct field. The struct field is a string and is expected to be assignable from users of my library. That\'s why I wa

Answer 1

To handle big structs you can use embedding.

Updated to not discard possibly previously set field values.

func (t *T) UnmarshalJSON(d []byte) error {
    type T2 T // create new type with same structure as T but without its method set!
    x := struct{
        T2 // embed
        Foo json.Number `json:"foo"`
    }{T2: T2(*t)} // don't forget this, if you do and 't' already has some fields set you would lose them

    if err := json.Unmarshal(d, &x); err != nil {
        return err
    }
    *t = T(x.T2)
    t.Foo = x.Foo.String()
    return nil
}

https://play.golang.org/p/BytXCeHMvt