#+TITLE: @apparts/errors #+DATE: [2021-02-11 Thu] #+AUTHOR: Philipp Uhl

An error-element used together with [[https://github.com/phuhl/apparts-types][@apparts/types]]. When returned or thrown within a function that is given to the preparator function (or prepauth, etc.), it will produce the corresponding HTTP error.

With the =fromThrows= helper function, you can remove nasty =try {} catch(e) {}= phrases that should return a value and normally require a non constant variable.

• Usage

#+BEGIN_SRC js const { HttpError, fromThrows } = require("@apparts/error");

// within @apparts/types preperator function: preperator({}, async () => { const somethingWrong = "blub"; if(somethingWrong) { return new HttpError(400, "You specified that parameter wrong", "Some dynamic info: " + somethingWrong); // --> http-statuscode 400, body: { error: "You specified that parameter wrong", // description: "Some dynamic info: blub" } } throw new HttpError(412, "Want to throw"); // --> http-statuscode 412, body: { error: "Want to throw" }

return HttpError.notFound("My element"); // --> http-statuscode 404, body: { error: "My element not found" }

if (!allowed) {
  return new HttpError(403); // --> http-statuscode 403, body: { error: "Forbidden" }
}


const data = fromThrows(() => JSON.parse("ha, you cant parse this!"),
                        SyntaxError,
                        e => new HttpError(400, "The data you send could net be parsed", e));
// If function throws SyntaxError, error will be re-thrown as 400-HttpError.
// If function throws different error, that error will be re-thrown (should give
// thanks to you a 500 server error thanks to preperator).
// If function returns normally, it's result is returned by fromThrows.

}); #+END_SRC