I always use `json.NewDecoder(r.Body).Decode(&payload)` The code is more succinct than reading the entire body into a buffer, and then unmarshalling it. And there is only one error to check.
If I was super concerned about people sending trailing gibberish to my server, I could call `dec.Buffered()` to see if there was anything left after the json object. I generally have not seen people sending garbage after their requests. And it is not clear what the correct action in these case is. I generally will ignore it. On occasions that I need to consume very large json arrays in my backend, without consuming much memory, I sometimes do something like https://play.golang.org/p/Isw_3p7mR5- On Tuesday, 29 December 2020 at 10:51:23 UTC axel.wa...@googlemail.com wrote: > There is an important semantic difference between the two, which means you > almost never want to use a `Decoder`: `Unmarshal` is for parsing a single > json document, whereas a `Decoder` is for parsing a stream of concatenated > documents, like so: https://play.golang.org/p/4uiNyJlNIKh. In particular, > this means that using a `Decoder` silently drops trailing data and might > not detect erronous json: https://play.golang.org/p/cuOAUnKCuEk > So, unless you specifically know that you have a stream of concatenated > json documents `Decoder` is not actually doing what you want. > > On Tue, Dec 29, 2020 at 11:37 AM Amit Saha <amits...@gmail.com> wrote: > >> On Tue, Dec 29, 2020 at 11:35 AM burak serdar <bse...@computer.org> >> wrote: >> > >> > On Mon, Dec 28, 2020 at 5:22 PM Amit Saha <amits...@gmail.com> wrote: >> > > >> > > Hi all, let's say I am a single large JSON object that I want to >> > > process in my HTTP server backend. >> > > >> > > I am trying to get my head around if there is any performance >> > > advantage - memory or CPU to use the json.NewDecoder()/Decode() >> > > mechanism versus the Unmarshal() function? >> > >> > Unmarshal uses the decoder for unmarshaling. Unless you are planning >> > to process the JSON object piece by piece using a decoder, the two are >> > identical in terms of performance. >> >> Thank you for confirming. >> >> >> > >> > > >> > > Thanks, >> > > Amit >> > > >> > > -- >> > > 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...@googlegroups.com. >> > > To view this discussion on the web visit >> https://groups.google.com/d/msgid/golang-nuts/CANODV3%3DU2KRRkvAAEfYqRtCVtYnh2dmGreqePF8QXLo1PriSPw%40mail.gmail.com >> . >> >> -- >> 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...@googlegroups.com. >> > To view this discussion on the web visit >> https://groups.google.com/d/msgid/golang-nuts/CANODV3%3DpXGcHzhSmaLr3f911i2CCYb0_j8CGH7zKAZXd_xTD-A%40mail.gmail.com >> . >> > -- 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/e9a6f76d-17bb-40da-84b3-2b1b8d0f3b35n%40googlegroups.com.
