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Re: calling a simple PyQt application more than once

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  Re: calling a simple PyQt application more than once John Posner <jjposner@optimum.net> - 2012-01-27 18:42 -0500

#19529 — Re: calling a simple PyQt application more than once

Jabba Laci wrote:
> Hi,
>
> I have a simple PyQt application that creates a webkit instance to
> scrape AJAX web pages. It works well but I can't call it twice. I
> think the application is not closed correctly, that's why the 2nd call
> fails. Here is the code below. I also put it on pastebin:
> http://pastebin.com/gkgSSJHY .
>
> The question is: how to call this code several times within a script.

You want to create/execute/quit a QApplication just once, not multiple
times.

I don't know either WebKit  or AJAX. In fact, I've never done any
networking with PyQt. But a little playing with the QtNetwork module
yielded this, using the QNetworkAccessManager and QNetworkRequest classes:

from PyQt4.QtCore import QUrl
from PyQt4.QtGui import QApplication, QPushButton
from PyQt4.QtNetwork import QNetworkAccessManager, QNetworkRequest

def process_page(reply_obj):
    resp = reply_obj.readAll()
    reply_obj.close()
    print str(resp).strip()

def do_click():
    req = QNetworkRequest(QUrl(MYURL))
    mgr.finished.connect(process_page)
    mgr.get(req)

MYURL = 'http://simile.mit.edu/crowbar/test.html'

if __name__ == "__main__":
    # we need only one application object and one net-access mgr
    app = QApplication([])
    mgr = QNetworkAccessManager()

    # the entire GUI is one button
    btn = QPushButton("Press me")
    btn.clicked.connect(do_click)
    btn.show()

    # start the event loop
    app.exec_()

You can click the "Press me" button as many times as you wish; it
retrieves and displays/prints the same HTML file on each click.

HTH,
John

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