EQL5/examples/X-extras/server-request.lisp

69 lines
2.7 KiB
Common Lisp

;;; this is just a snippet to show how to use Qt for POST requests to
;;; a cgi script (using e.g. python for cgi)
;;;
;;; this is here to have an alternative to Lisp solutions, which don't
;;; work well in ECL on some platforms (namely Windows)
;;;
;;; example usage:
;;;
;;; (server-request "booking.py"
;;; (list (cons "from" "2020-08-01")
;;; (cons "to" "2020-08-08")))
;;;
;;; please note the use of QLET to have all locally created Qt objects deleted
;;; when leaving the function body;
;;;
;;; note also how this is done with function HTTP-PART, where we can't use QLET
;;; inside the function for 'QHttpPart', because we need to return the newly
;;; created Qt object; in this case, QLET is placed in the caller, see:
;;;
;;; (dolist...
;;; (qlet ((part (http-part param)))
;;; (|append|...
;;;
;;; ...and since we are at it, just a reminder:
;;;
;;; as you already should know, QLET is crucial for all only locally used Qt
;;; objects, because it guarantees two things:
;;; - the C++ destructors being called when leaving the QLET body
;;; - not leaving around some garbage (GC through finalizing is only implemen-
;;; ted for return values from Qt function calls)
(qrequire :network)
;; for testing, using e.g. python3 -m http.server 8080 --cgi
(defparameter *server* "http://localhost:8080/cgi-bin/")
(defun http-part (parameter)
(let ((part (qnew "QHttpPart")))
(qlet ((name "QVariant(QString)"
(format nil "form-data; name=~S" (car parameter))))
(|setHeader| part |QNetworkRequest.ContentDispositionHeader| name)
(|setBody| part (x:string-to-bytes (cdr parameter))))
part))
(defun server-request (script &optional parameters)
"Make a http POST request to a cgi script, forcing synchronous behaviour,
which simplifies things and is preferable in many cases."
(start-busy-animation) ; pseudo code
(let (response)
(qlet ((ev-loop "QEventLoop")
(manager "QNetworkAccessManager"))
(qconnect manager "finished(QNetworkReply*)"
(lambda (reply)
(|deleteLater| reply)
(let ((err (|error| reply)))
(when (= |QNetworkReply.NoError| err)
(setf response (qfrom-utf8 (|readAll| reply)))))
(|exit| ev-loop)))
(qlet ((multi "QHttpMultiPart")
(qurl "QUrl(QString)" (x:cc *server* script))
(request "QNetworkRequest(QUrl)" qurl))
(dolist (param parameters)
(qlet ((part (http-part param)))
(|append| multi part)))
(|post| manager request multi)
(|exec| ev-loop |QEventLoop.ExcludeUserInputEvents|)
(stop-busy-animation) ; pseudo code
response))))