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Thread: QLineEdit not updating as expected

  1. #1
    Join Date
    Apr 2010
    Posts
    9
    Qt products
    Qt4
    Platforms
    Unix/X11 Windows

    Default QLineEdit not updating as expected

    Dear All

    Please consider the following function:

    Qt Code:
    1. void CTL_Main::useDBParamteters1(QString DB_IP, int DB_PORT, QString DB_USER, QString DB_PASS){
    2.  
    3. MySQL_DB testing_query(DB_IP, DB_PORT, DB_USER, DB_PASS);
    4. float resultofquery = testing_query.getAIRTemperature();
    5.  
    6. QString results_string;
    7. results_string.setNum(resultofquery);
    8. qDebug() << results_string;
    9.  
    10. ui->lineAIRTemp->setText(results_string);
    11. QMessageBox::information(this, "Debug Data", "Current Temperature: " + results_string);
    12.  
    13. return;
    To copy to clipboard, switch view to plain text mode 

    This function instantiates a instance of the MySQL_DB class and passes the database parameters to the constructor, then runs the getAIRTemperature() method which loads the results into a float. I then do a dirty conversion into a QString.

    The correct value is displayed by qDebug() and in the QMessageBox but nothing is placed into QLineEdit (lineAIRTemp at line 10).

    This is driving me crazy, can anybody help?

    Many thanks
    Ishtar

  2. #2
    Join Date
    Oct 2008
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    Thanked 1 Time in 1 Post
    Qt products
    Qt4
    Platforms
    MacOS X

    Default Re: QLineEdit not updating as expected

    Are you sure that the text is not reset from some other part of the code?
    Try to handle this signal:
    Qt Code:
    1. void QLineEdit::textChanged ( const QString & text ) [signal]
    To copy to clipboard, switch view to plain text mode 
    And see what's happening to the text.

  3. #3
    Join Date
    Apr 2010
    Posts
    9
    Qt products
    Qt4
    Platforms
    Unix/X11 Windows

    Default Re: QLineEdit not updating as expected

    Hi and many thanks for your help.

    Yes, absolutely sure because the QMessageBox at line 11 and the qDebug() at line 8 shows the value of this variable. It just doesn't update the QLineEdit. Any other ideas?

    Once again, thank you.
    Ishtar

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