As explained above, `type AliasedDate Date` clears any methods you have defined on `Date`. But `Date` embeds `time.Time` which has its own `UnmrshalJSON`, which now gets promoted.
So `Date.UnmsrshalJSON` calls your `UnmsrshalJSON` `AliastedDate.UnmsrshalJSON` calls `AliastedDate.Time.UnmsrshalJSON` On Fri, May 20, 2022 at 3:14 PM Marcin Romaszewicz <marc...@gmail.com> wrote: > Sorry about mixing up terms, however, my question still stands. > > encoding/json looks for the Marshaler/Unmarshaler interface > convertibility, and in this case, the compiler thinks that the redeclared > type does implement json.Unmarshaler. I extended my example to also do this > test via reflection. > > https://go.dev/play/p/TrxM2zxG2pX > > So, yes, it's a new type, but it seems to behave just like the base type. > > On Fri, May 20, 2022 at 12:35 AM Axel Wagner < > axel.wagner...@googlemail.com> wrote: > >> It's not an "aliased type". Type aliases take the form >> type A = B >> and they make the name A be interchangeable with the name B. What you >> have is a type declaration >> type A B >> which creates a fully new type, with a new method set, but the same >> underlying type as B. >> >> On Fri, May 20, 2022 at 9:28 AM Marcin Romaszewicz <marc...@gmail.com> >> wrote: >> >>> Hi All, >>> >>> I've created a simple struct that wraps time.Time because I'd like to >>> unmarshal it differently from JSON than the default. It works great. >>> >>> However, when I pass a type alias of that struct to json.Marshal or >>> json.Unmarshal, the MarshalJSON and UnmarshalJSON functions aren't invoked, >>> despite both types conforming to the interfaces. >>> >>> Here's the shortest example I could make. >>> https://go.dev/play/p/pETWQB3CWxV >>> >>> This is where this came up: >>> https://github.com/deepmap/oapi-codegen/issues/579 >>> >>> I did find a workaround, in redeclaring the MarshalJSON/UnmarshalJSON on >>> the aliased type, but I don't understand why this is necessary, and I'm >>> hoping someone who understands the innards of this better than I do could >>> enlighten me. >>> >>> Thanks, >>> -- Marcin >>> >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "golang-nuts" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to golang-nuts+unsubscr...@googlegroups.com. >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/golang-nuts/CA%2Bv29LuOa9sHFWxPxqYq_HtiQZ6_pUhCtMUOAL8Yq1X_UvyjJw%40mail.gmail.com >>> <https://groups.google.com/d/msgid/golang-nuts/CA%2Bv29LuOa9sHFWxPxqYq_HtiQZ6_pUhCtMUOAL8Yq1X_UvyjJw%40mail.gmail.com?utm_medium=email&utm_source=footer> >>> . >>> >> -- > You received this message because you are subscribed to the Google Groups > "golang-nuts" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to golang-nuts+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/golang-nuts/CA%2Bv29LvC7NY-wGXX9JUQAcGPohLB_puPz0F2Nehsq7Xx2zAZeg%40mail.gmail.com > <https://groups.google.com/d/msgid/golang-nuts/CA%2Bv29LvC7NY-wGXX9JUQAcGPohLB_puPz0F2Nehsq7Xx2zAZeg%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/CAGabyPpyzxzpqNy%3DqFo3pdRp2HT8Gks-xSB9e7KLmEVG%3DTb%2Bwg%40mail.gmail.com.
