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Comment by groestl

7 years ago

Idempotency might be necessary for GET calls, but it's not sufficient. Imagine he had two separate GET calls (opened/closed): the author would still have the same problem. Browsers assume GET to be safe (non-mutating), and safety implies idempotency.

22 comments

groestl

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onion2k  7 years ago

Exactly. A 'toggle' should really be implemented as a PATCH request, or maybe a PUT if there's no data other than the door state.

  • hardwaresofton  7 years ago

    At the risk of being overly pedantic/piling on -- this is what bad REST-ful API design looks like in practice.

    When you talk to your teammates about the semantics of these verbs and someone just says "oh a GET is fine" and the team agrees but you don't and you can't say it so you don't become "that guy" it's time to find a new engineering org to be a part of.

    On the topic of PATCH, check out JSON merge patches (application/merge-patch+json):

    https://tools.ietf.org/html/rfc7386

    • Senderman  7 years ago

      I hope this doesn't come across as mean-spirited, but I'm really struck by the middle part of your comment, even though I think it was meant as a throwaway remark.

      It sounds like you're advocating leaving an organisation instead of speaking up when a mistake is being made? In the scenario you described, the "a GET is fine" person is unfamiliar with the protocol they're writing for (HTTP), and so is every person who agreed. Leaving instead of speaking up seems pretty drastic.

      2 replies →

    • strictnein  7 years ago

      Hadn't seen that RFC before. We were doing almost exactly that on a large API project a year or so before that RFC was published. Backend guys hated it, front end guys loved it.

  • mvindahl  7 years ago

    Absolutely agree. A PUT method carrying an open/closed flag would seem like a natural choice. Calling it any number of consecutive times with the same payload would be idempotent. There would probably be a GET method to go along with it. And of course, it would model the desired state, not the actual position of the garage door since garage doors don't instantaneously flip (would be cool though).

  • dragonwriter  7 years ago

    A toggle would actually be a good use of POST, though PUTting the desired state would be better (PATCH works instead of PUT if you are changing some part of the state and not the whole state, but is unnecessary if the door state consists entirely of either “open” or ”closed”.)

z3t4  7 years ago

HTTP GET is nice because you can "debug" via browser. But I don't think it's a good protocol choice for opening/closing doors nor any other service not related to document requests.