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Why this date.fromstring is not working ?

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  • R RahibeMeryem

    Hi,

    Below code gives invalid Date, what am I missing ?

    DATE.fromString("17-19-47 2019-12-10" , "hh-mm-ss yyyy-MM-dd")
    
    jsulmJ Offline
    jsulmJ Offline
    jsulm
    Lifetime Qt Champion
    wrote on last edited by
    #2

    @RahibeMeryem fromString is static, no need for DATE:

    QDate::fromString("17-19-47 2019-12-10" , "hh-mm-ss yyyy-MM-dd");
    

    https://forum.qt.io/topic/113070/qt-code-of-conduct

    1 Reply Last reply
    5
    • R RahibeMeryem

      Hi,

      Below code gives invalid Date, what am I missing ?

      DATE.fromString("17-19-47 2019-12-10" , "hh-mm-ss yyyy-MM-dd")
      
      J.HilkJ Online
      J.HilkJ Online
      J.Hilk
      Moderators
      wrote on last edited by
      #3

      @RahibeMeryem in addition to to @jsulm

      as a static function, fromString returns a new Date and does not manipulate the QDate where you call it from.

      So, do you assign it? aka:

      DATE = DATE.fromString("17-19-47 2019-12-10" , "hh-mm-ss yyyy-MM-dd")


      Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct


      Q: What's that?
      A: It's blue light.
      Q: What does it do?
      A: It turns blue.

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      • SGaistS Offline
        SGaistS Offline
        SGaist
        Lifetime Qt Champion
        wrote on last edited by SGaist
        #4

        Hi,

        In addition to my fellows:
        DATE = QDate::fromString("2019-12-10" , "yyyy-MM-dd");

        is the conventional way to call a static function. It shows clearly that you are using a static function and want to get back the value it returns.

        [edit: Removed time related formatting as it's not related to QDate SGaist]

        Interested in AI ? www.idiap.ch
        Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

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        • R Offline
          R Offline
          RahibeMeryem
          wrote on last edited by
          #5

          @SGaist said in Why this date.fromstring is not working ?:

          DATE = QDate::fromString("17-19-47 2019-12-10" , "hh-mm-ss yyyy-MM-dd");

                  QDate DATE2 = QDate::fromString("17-19-47 2019-12-10" , "hh-mm-ss yyyy-MM-dd");        
          
          

          Still gives Invalid error DATE2 Inalid

          .. What am I missing ?

          jsulmJ JonBJ 2 Replies Last reply
          0
          • R RahibeMeryem

            @SGaist said in Why this date.fromstring is not working ?:

            DATE = QDate::fromString("17-19-47 2019-12-10" , "hh-mm-ss yyyy-MM-dd");

                    QDate DATE2 = QDate::fromString("17-19-47 2019-12-10" , "hh-mm-ss yyyy-MM-dd");        
            
            

            Still gives Invalid error DATE2 Inalid

            .. What am I missing ?

            jsulmJ Offline
            jsulmJ Offline
            jsulm
            Lifetime Qt Champion
            wrote on last edited by
            #6

            @RahibeMeryem Change hh to HH

            https://forum.qt.io/topic/113070/qt-code-of-conduct

            1 Reply Last reply
            1
            • R RahibeMeryem

              @SGaist said in Why this date.fromstring is not working ?:

              DATE = QDate::fromString("17-19-47 2019-12-10" , "hh-mm-ss yyyy-MM-dd");

                      QDate DATE2 = QDate::fromString("17-19-47 2019-12-10" , "hh-mm-ss yyyy-MM-dd");        
              
              

              Still gives Invalid error DATE2 Inalid

              .. What am I missing ?

              JonBJ Offline
              JonBJ Offline
              JonB
              wrote on last edited by JonB
              #7

              @RahibeMeryem
              I don't know whether what @jsulm has just written is correct or not, but https://doc.qt.io/qt-5/qdate.html#fromString-1 says it only accepts date format specifiers, you have date and time. Don't you need QDateTime::fromString(), as in https://doc.qt.io/qt-5/qdatetime.html#fromString-1 ? Then you may want the HH instead of hh (read the doc page for the distinction).

              jsulmJ 2 Replies Last reply
              0
              • JonBJ JonB

                @RahibeMeryem
                I don't know whether what @jsulm has just written is correct or not, but https://doc.qt.io/qt-5/qdate.html#fromString-1 says it only accepts date format specifiers, you have date and time. Don't you need QDateTime::fromString(), as in https://doc.qt.io/qt-5/qdatetime.html#fromString-1 ? Then you may want the HH instead of hh (read the doc page for the distinction).

                jsulmJ Offline
                jsulmJ Offline
                jsulm
                Lifetime Qt Champion
                wrote on last edited by
                #8

                @JonB said in Why this date.fromstring is not working ?:

                what @jsulm has just written is correct or not

                It is - just tested.

                https://forum.qt.io/topic/113070/qt-code-of-conduct

                JonBJ 2 Replies Last reply
                1
                • jsulmJ jsulm

                  @JonB said in Why this date.fromstring is not working ?:

                  what @jsulm has just written is correct or not

                  It is - just tested.

                  JonBJ Offline
                  JonBJ Offline
                  JonB
                  wrote on last edited by JonB
                  #9

                  @jsulm
                  You tested it with QDate instead of QDateTime, when the OP is passing a date+time value and date+time format? He wants to pass in a date+time with all the formatting for time too, yet he only wants a date returned?

                  1 Reply Last reply
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                  • JonBJ JonB

                    @RahibeMeryem
                    I don't know whether what @jsulm has just written is correct or not, but https://doc.qt.io/qt-5/qdate.html#fromString-1 says it only accepts date format specifiers, you have date and time. Don't you need QDateTime::fromString(), as in https://doc.qt.io/qt-5/qdatetime.html#fromString-1 ? Then you may want the HH instead of hh (read the doc page for the distinction).

                    jsulmJ Offline
                    jsulmJ Offline
                    jsulm
                    Lifetime Qt Champion
                    wrote on last edited by
                    #10

                    @JonB @RahibeMeryem Yes, with QDateTime it works with hh also.
                    Sometimes it's so easy :-)

                    https://forum.qt.io/topic/113070/qt-code-of-conduct

                    JonBJ 1 Reply Last reply
                    0
                    • jsulmJ jsulm

                      @JonB @RahibeMeryem Yes, with QDateTime it works with hh also.
                      Sometimes it's so easy :-)

                      JonBJ Offline
                      JonBJ Offline
                      JonB
                      wrote on last edited by
                      #11

                      @jsulm
                      My point being: if you really only want a QDate back, why would you include the time specifiers in the format string? I'm wondering whether the user intends QDateTime::fromString()...?

                      jsulmJ 1 Reply Last reply
                      0
                      • JonBJ JonB

                        @jsulm
                        My point being: if you really only want a QDate back, why would you include the time specifiers in the format string? I'm wondering whether the user intends QDateTime::fromString()...?

                        jsulmJ Offline
                        jsulmJ Offline
                        jsulm
                        Lifetime Qt Champion
                        wrote on last edited by
                        #12

                        @JonB said in Why this date.fromstring is not working ?:

                        My point being: if you really only want a QDate back, why would you include the time specifiers in the format string?

                        You should ask OP, not me

                        https://forum.qt.io/topic/113070/qt-code-of-conduct

                        JonBJ 1 Reply Last reply
                        0
                        • jsulmJ jsulm

                          @JonB said in Why this date.fromstring is not working ?:

                          My point being: if you really only want a QDate back, why would you include the time specifiers in the format string?

                          You should ask OP, not me

                          JonBJ Offline
                          JonBJ Offline
                          JonB
                          wrote on last edited by
                          #13

                          @jsulm
                          My use of "you" is the "communal" "you", not the "personal" "you" aimed at you :)

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                          • jsulmJ jsulm

                            @JonB said in Why this date.fromstring is not working ?:

                            what @jsulm has just written is correct or not

                            It is - just tested.

                            JonBJ Offline
                            JonBJ Offline
                            JonB
                            wrote on last edited by JonB
                            #14

                            @jsulm , @RahibeMeryem
                            I'm sorry, but it is not the HH vs hh (don't know what you tested for that @jsulm), it is indeed as I said that you need QDateTime for your format:

                            >>> from PySide2 import QtCore
                            >>> QtCore.QDate.fromString("17-19-47 2019-12-10" , "hh-mm-ss yyyy-MM-dd")
                            PySide2.QtCore.QDate(0, 0, 0)
                            >>> QtCore.QDateTime.fromString("17-19-47 2019-12-10" , "hh-mm-ss yyyy-MM-dd")
                            PySide2.QtCore.QDateTime(2019, 12, 10, 17, 19, 47, 0, 0)
                            >>> QtCore.QDate.fromString("17-19-47 2019-12-10" , "HH-mm-ss yyyy-MM-dd")
                            PySide2.QtCore.QDate(0, 0, 0)
                            >>> QtCore.QDateTime.fromString("17-19-47 2019-12-10" , "HH-mm-ss yyyy-MM-dd")
                            PySide2.QtCore.QDateTime(2019, 12, 10, 17, 19, 47, 0, 0)
                            >>> 
                            
                            

                            The reason being: if you use QDate, the leading "HH-mm-ss" or whatever will not match against the time, instead it will be treated as literal and therefore the input will fail to match, whatever you do....

                            jsulmJ 1 Reply Last reply
                            0
                            • JonBJ JonB

                              @jsulm , @RahibeMeryem
                              I'm sorry, but it is not the HH vs hh (don't know what you tested for that @jsulm), it is indeed as I said that you need QDateTime for your format:

                              >>> from PySide2 import QtCore
                              >>> QtCore.QDate.fromString("17-19-47 2019-12-10" , "hh-mm-ss yyyy-MM-dd")
                              PySide2.QtCore.QDate(0, 0, 0)
                              >>> QtCore.QDateTime.fromString("17-19-47 2019-12-10" , "hh-mm-ss yyyy-MM-dd")
                              PySide2.QtCore.QDateTime(2019, 12, 10, 17, 19, 47, 0, 0)
                              >>> QtCore.QDate.fromString("17-19-47 2019-12-10" , "HH-mm-ss yyyy-MM-dd")
                              PySide2.QtCore.QDate(0, 0, 0)
                              >>> QtCore.QDateTime.fromString("17-19-47 2019-12-10" , "HH-mm-ss yyyy-MM-dd")
                              PySide2.QtCore.QDateTime(2019, 12, 10, 17, 19, 47, 0, 0)
                              >>> 
                              
                              

                              The reason being: if you use QDate, the leading "HH-mm-ss" or whatever will not match against the time, instead it will be treated as literal and therefore the input will fail to match, whatever you do....

                              jsulmJ Offline
                              jsulmJ Offline
                              jsulm
                              Lifetime Qt Champion
                              wrote on last edited by jsulm
                              #15

                              @JonB That's why I wrote "Yes, with QDateTime it works with hh also.".
                              With QDate it works with HH, but not hh - I tested that:

                              QDate DATE2 = QDate::fromString("17-19-47 2019-12-10" , "HH-mm-ss yyyy-MM-dd");
                              

                              And yes, it is correct that one should use QDateTime instead of QDate if there is time and date.

                              https://forum.qt.io/topic/113070/qt-code-of-conduct

                              JonBJ 1 Reply Last reply
                              0
                              • jsulmJ jsulm

                                @JonB That's why I wrote "Yes, with QDateTime it works with hh also.".
                                With QDate it works with HH, but not hh - I tested that:

                                QDate DATE2 = QDate::fromString("17-19-47 2019-12-10" , "HH-mm-ss yyyy-MM-dd");
                                

                                And yes, it is correct that one should use QDateTime instead of QDate if there is time and date.

                                JonBJ Offline
                                JonBJ Offline
                                JonB
                                wrote on last edited by JonB
                                #16

                                @jsulm
                                If it works for you with HH plus QDate, could you please explain the output I showed above where it does not work? Thanks.

                                >>> QtCore.QDate.fromString("17-19-47 2019-12-10" , "HH-mm-ss yyyy-MM-dd")
                                PySide2.QtCore.QDate(0, 0, 0)
                                

                                which is an invalid QDate. I am Qt 5.12.2, Ubuntu 19.04.

                                jsulmJ 1 Reply Last reply
                                0
                                • J.HilkJ Online
                                  J.HilkJ Online
                                  J.Hilk
                                  Moderators
                                  wrote on last edited by
                                  #17

                                  From my point of view, your both wrong @JonB & @jsulm πŸ˜‰

                                  the docu only states https://doc.qt.io/qt-5/qdate.html#fromString-1

                                  that only yand Mand dare valid formats everything else is interpreted as a literal character.

                                  and my test confirms it:

                                  int main(int argc, char *argv[])
                                  {
                                      QApplication a(argc, argv);
                                  
                                  
                                      QDate d1 = QDate::fromString("17-19-47 2019-12-10" , "hh-mm-ss yyyy-MM-dd");
                                      QDate d2 = QDate::fromString("17-19-47 2019-12-10" , "HH-mm-ss yyyy-MM-dd");
                                  
                                      QDate d3 = QDate::fromString("17-19-47 2019-12-10" , "17-19-47 yyyy-MM-dd");
                                      QDate d4 = QDateTime::fromString("17-19-47 2019-12-10" , "hh-mm-ss yyyy-MM-dd").date();
                                      qDebug() << d1 << d2 << d3 << d4;
                                  
                                  //    return a.exec();
                                  }
                                  
                                  Result:
                                  QDate(Invalid) QDate(Invalid) QDate("2019-12-10") QDate("2019-12-10")
                                  

                                  Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct


                                  Q: What's that?
                                  A: It's blue light.
                                  Q: What does it do?
                                  A: It turns blue.

                                  JonBJ 1 Reply Last reply
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                                  • JonBJ JonB

                                    @jsulm
                                    If it works for you with HH plus QDate, could you please explain the output I showed above where it does not work? Thanks.

                                    >>> QtCore.QDate.fromString("17-19-47 2019-12-10" , "HH-mm-ss yyyy-MM-dd")
                                    PySide2.QtCore.QDate(0, 0, 0)
                                    

                                    which is an invalid QDate. I am Qt 5.12.2, Ubuntu 19.04.

                                    jsulmJ Offline
                                    jsulmJ Offline
                                    jsulm
                                    Lifetime Qt Champion
                                    wrote on last edited by
                                    #18

                                    @JonB OK, correction: with QDate it does not work (not with hh and not with HH). I was thinking it does, because my small test application outputs date/time in another place, so it was looking like it was working. Sorry for confusion :-)

                                    https://forum.qt.io/topic/113070/qt-code-of-conduct

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                                    • J.HilkJ J.Hilk

                                      From my point of view, your both wrong @JonB & @jsulm πŸ˜‰

                                      the docu only states https://doc.qt.io/qt-5/qdate.html#fromString-1

                                      that only yand Mand dare valid formats everything else is interpreted as a literal character.

                                      and my test confirms it:

                                      int main(int argc, char *argv[])
                                      {
                                          QApplication a(argc, argv);
                                      
                                      
                                          QDate d1 = QDate::fromString("17-19-47 2019-12-10" , "hh-mm-ss yyyy-MM-dd");
                                          QDate d2 = QDate::fromString("17-19-47 2019-12-10" , "HH-mm-ss yyyy-MM-dd");
                                      
                                          QDate d3 = QDate::fromString("17-19-47 2019-12-10" , "17-19-47 yyyy-MM-dd");
                                          QDate d4 = QDateTime::fromString("17-19-47 2019-12-10" , "hh-mm-ss yyyy-MM-dd").date();
                                          qDebug() << d1 << d2 << d3 << d4;
                                      
                                      //    return a.exec();
                                      }
                                      
                                      Result:
                                      QDate(Invalid) QDate(Invalid) QDate("2019-12-10") QDate("2019-12-10")
                                      
                                      JonBJ Offline
                                      JonBJ Offline
                                      JonB
                                      wrote on last edited by JonB
                                      #19

                                      @J-Hilk said in Why this date.fromstring is not working ?:

                                      From my point of view, your both wrong @JonB & @jsulm πŸ˜‰

                                      Interesting, because what you have shown is exactly what I have said! :)

                                      In the case of working

                                      QDate d3 = QDate::fromString("17-19-47 2019-12-10" , "17-19-47 yyyy-MM-dd");
                                      

                                      that works only because the literal leading 17-19-47 in the format string matches the input without "placeholder substitutions".

                                      As for the HH vs hh when using QDateTime, that should be irrelevant for the input shown, as per https://doc.qt.io/qt-5/qdatetime.html#fromString-1

                                      hh the hour with a leading zero (00 to 23 or 01 to 12 if AM/PM display)
                                      HH the hour with a leading zero (00 to 23, even with AM/PM display)

                                      as the only difference is to do with "AM/PM", which the input string does not have.

                                      J.HilkJ 1 Reply Last reply
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                                      • JonBJ JonB

                                        @J-Hilk said in Why this date.fromstring is not working ?:

                                        From my point of view, your both wrong @JonB & @jsulm πŸ˜‰

                                        Interesting, because what you have shown is exactly what I have said! :)

                                        In the case of working

                                        QDate d3 = QDate::fromString("17-19-47 2019-12-10" , "17-19-47 yyyy-MM-dd");
                                        

                                        that works only because the literal leading 17-19-47 in the format string matches the input without "placeholder substitutions".

                                        As for the HH vs hh when using QDateTime, that should be irrelevant for the input shown, as per https://doc.qt.io/qt-5/qdatetime.html#fromString-1

                                        hh the hour with a leading zero (00 to 23 or 01 to 12 if AM/PM display)
                                        HH the hour with a leading zero (00 to 23, even with AM/PM display)

                                        as the only difference is to do with "AM/PM", which the input string does not have.

                                        J.HilkJ Online
                                        J.HilkJ Online
                                        J.Hilk
                                        Moderators
                                        wrote on last edited by
                                        #20

                                        @JonB πŸ˜†sorry I got the impression you were arguing for the lower case hhwhich is of course wrong in Date::fromString() missed the other post!


                                        Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct


                                        Q: What's that?
                                        A: It's blue light.
                                        Q: What does it do?
                                        A: It turns blue.

                                        1 Reply Last reply
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