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PostgreSQL and Trying to connect using Qt

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  • A Offline
    A Offline
    aftertaf
    wrote on last edited by
    #30

    ...
    just build libpq.a from sources . . . .
    http://pgolub.wordpress.com/2008/12/15/building-postgresql-client-library-using-mingw-under-winxp-sp3/

    don't know what to do with it.
    sorry for by n00bness, people...

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    0
    • C Offline
      C Offline
      clochydd
      wrote on last edited by
      #31

      It is not necessary to compile postgresql, I used the binaries 32-bit and with installing ./lib and ./include had been provided, too.
      Your make does not recognise the psql includes (the stuff, that follows -I) and that's why you still receive the message 'libpq-fe.h not found'.
      Do you see the same error if you use backslashed paths with you qmake command? Qt uses forward slashes but I had success with the backslashed command.

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      • SGaistS Offline
        SGaistS Offline
        SGaist
        Lifetime Qt Champion
        wrote on last edited by
        #32

        Just to be sure, wouldn't by any chance libpq-fe.h be in include/libpq ? If so it's that last element that was missing.

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        • C Offline
          C Offline
          clochydd
          wrote on last edited by
          #33

          Yes, this has been installed in "C:\Program Files (x86)\PostgreSQL\9.3\include" together with the binaries of PostgeSQL 32-bit:
          "03.12.2013 06:13 21.082 libpq-fe.h"
          and - the PostgreSQl include has to be added to qmake!

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          • SGaistS Offline
            SGaistS Offline
            SGaist
            Lifetime Qt Champion
            wrote on last edited by
            #34

            Indeed, but you need to give the full path to libqp-fe.h not just the path that contains the libpq folder.

            Please avoid having spaces in your path when developing, it something that is not working very well on windows

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            • A Offline
              A Offline
              aftertaf
              wrote on last edited by
              #35

              on my system i installed postgreSQL x86 9.3 to c:\psql93_x86\

              so... the qmake command where i specify the INCLUDE+=, LIBS+= etc . . .
              i need to tell it precisely and exactly where libqp-fe.h is, including full path ?

              how do I do that, i.e. what separator do i use to add more than one entry into the "INCLUDE+=" that i've already specified (using clochydd's tuto on page 2. .) ?

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              • C Offline
                C Offline
                clochydd
                wrote on last edited by
                #36

                Go to the Qt plugin source directory:
                cd QT_SRC_PATH\src\plugins\sqldrivers\psql

                Start building the plugins:
                (Change this to your mingw32 path: C:\Qt\Qt5.2.0\5.2.0\mingw48_32\bin)
                C:\Qt\Qt5.2.0\5.2.0\mingw48_32\bin\qmake “INCLUDEPATH+=c:\psql93_x86\include”
                “LIBS+=c:\psql93_x86\lib\libpq.lib” psql.pro

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                • SGaistS Offline
                  SGaistS Offline
                  SGaist
                  Lifetime Qt Champion
                  wrote on last edited by
                  #37

                  libpq-fe.h being in include/libpq

                  You should use

                  @“INCLUDEPATH+=c:/psql93_x86/include/libpq”@

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                  • A Offline
                    A Offline
                    aftertaf
                    wrote on last edited by
                    #38

                    same :(

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                    • C Offline
                      C Offline
                      clochydd
                      wrote on last edited by
                      #39

                      Don't give up - we will find a solution, hopefully!

                      • Is the qmake error message concerning the libpq-fe.h exactly as before?
                      • Could you please post the message again?
                      • Could you post the directory list of c:\psql93_x86\include?
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                      • A Offline
                        A Offline
                        aftertaf
                        wrote on last edited by
                        #40

                        just tried making the odbc driver again...
                        and get the Driver not Loaded message :)


                        C:\QT\5.2.1\Src\qtbase\src\plugins\sqldrivers\psql>c:\Qt\5.2.1\mingw48_32\bin\qm
                        ake.exe "INCLUDEPATH+=c:/psql93_x86/include/libpq" "LIBS+=c:/psql93_x86/lib/libp
                        q.lib" psql.pro

                        C:\QT\5.2.1\Src\qtbase\src\plugins\sqldrivers\psql>mingw32-make debug
                        mingw32-make -f Makefile.Debug
                        mingw32-make[1]: Entering directory 'C:/QT/5.2.1/Src/qtbase/src/plugins/sqldrive
                        rs/psql'
                        g++ -c -pipe -fno-keep-inline-dllexport -g -std=c++0x -fno-exceptions -frtti -Wa
                        ll -Wextra -DUNICODE -DQT_NO_CAST_TO_ASCII -DQT_NO_CAST_FROM_ASCII -DQT_NO_EXCEP
                        TIONS -DQT_PLUGIN -DQT_SQL_LIB -DQT_CORE_LIB -I. -I"C:\Qt\5.2.1\mingw48_32\inclu
                        de\QtSql\5.2.1" -I"C:\Qt\5.2.1\mingw48_32\include\QtSql\5.2.1\QtSql" -I"C:\Qt\5.
                        2.1\mingw48_32\include" -I"C:\Qt\5.2.1\mingw48_32\include\QtSql" -I"C:\Qt\5.2.1
                        mingw48_32\include\QtCore\5.2.1" -I"C:\Qt\5.2.1\mingw48_32\include\QtCore\5.2.1
                        QtCore" -I"C:\Qt\5.2.1\mingw48_32\include\QtCore" -I".moc\debug" -I"........
                        mkspecs\win32-g++" -o .obj\debug\qsql_psql.o ......\sql\drivers\psql\qsql_psql
                        .cpp
                        ......\sql\drivers\psql\qsql_psql.cpp:59:22: fatal error: libpq-fe.h: No such
                        file or directory
                        #include <libpq-fe.h>
                        ^
                        compilation terminated.
                        Makefile.Debug:497: recipe for target '.obj/debug/qsql_psql.o' failed
                        mingw32-make[1]: *** [.obj/debug/qsql_psql.o] Error 1
                        mingw32-make[1]: Leaving directory 'C:/QT/5.2.1/Src/qtbase/src/plugins/sqldriver
                        s/psql'
                        makefile:48: recipe for target 'debug' failed
                        mingw32-make: *** [debug] Error 2

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                        • A Offline
                          A Offline
                          aftertaf
                          wrote on last edited by
                          #41

                          http://pastebin.com/4cpqVMiN
                          folder contents

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                          0
                          • C Offline
                            C Offline
                            clochydd
                            wrote on last edited by
                            #42

                            Thanks for the data! I can see our "fatal" libpq-fe.h in c:\psql93_x86\include. So as a first step I suppose to test with:
                            C:\QT\5.2.1\Src\qtbase\src\plugins\sqldrivers\psql>c:\Qt\5.2.1\mingw48_32\bin\qmake.exe “INCLUDEPATH+=c:\psql93_x86\include” “LIBS+=c:\psql93_x86\lib\libpq.lib” psql.pro
                            I know, the backslashes are a bit unusual for Qt but it worked with my installs so give it a try! Good luck!

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                            • A Offline
                              A Offline
                              aftertaf
                              wrote on last edited by
                              #43

                              i've tried on many occasions with \ and /: same result.

                              The problem is obviously over my level of unkludging, and I've figured out how to use ODBC instead.

                              @
                              #include <QtSql>
                              #include <QString>
                              #include <QSqlDatabase>

                              void connect_db()
                              {

                              QSqlDatabase db = QSqlDatabase::addDatabase("QODBC");
                              QStringList driversList = QSqlDatabase::drivers();
                              qDebug() << "drivers list= " << driversList;
                              bool bOpen(false);
                              db.addDatabase("QODBC","odbcname");
                              db.setHostName("localhost");
                              db.setDatabaseName("dbname_in_postgres");
                              db.setUserName("username");
                              db.setPassword("password");
                              bOpen =db.open();
                              QString str=db.lastError().text();
                              }@

                              str remains empty :)
                              and bOpen shows True for the first time in a month's trying.
                              I dont need pure pg connection, using an ODBC is fine for me at this stage.
                              Now for trying to make my DAO classes :)
                              thanks to all for helping, sorry it didn't work out as intended, but for ODBC connections, my above code works.

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                              • DuncanD Offline
                                DuncanD Offline
                                Duncan
                                wrote on last edited by
                                #44

                                Hello!

                                What did you put for this line:

                                db.addDatabase("QODBC","odbcname");

                                Not sure what to put instead of odbcname.

                                Thanks!

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                                • C Offline
                                  C Offline
                                  clochydd
                                  wrote on last edited by
                                  #45

                                  Hello Duncan,

                                  if you only open one database, you do not need to specify the connection name:

                                  db.addDatabase("QODBC");
                                  

                                  If you plan work with more connections, use a name to identify each connection:

                                  db.addDatabase("QODBC","myConn1");
                                  
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                                  • SGaistS Offline
                                    SGaistS Offline
                                    SGaist
                                    Lifetime Qt Champion
                                    wrote on last edited by
                                    #46

                                    Hi,

                                    addDatabase is a static function that returns a QSqlDatabase instance that will use the selected backend.

                                    So you must call it like that:
                                    QSqlDatabase db = QSqlDatabase::addDatabase("QODBC")

                                    The suggestion of @clochydd about the connection name still applies.

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                                    Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

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