PostgreSQL and Trying to connect using Qt
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You are using mingw32's gcc to compile qt and trying to use postgreql library compiled with MSVC.
MSVC uses .LIB for libraries while Mingw32 (gcc + binutils) uses .a or .so files for libraries.
You can try either of the following methods: a. compile Qt using MSVC. b. use mingw32 to compile postgresql and use its libraries.
From:
http://stackoverflow.com/questions/5487236/building-qt-postgresql-driveranyone have an easy to follow 'how to build postgres from sources with mingw '?
or easier still, how to "use" the "QT" ODBC driver instead? -
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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... -
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. -
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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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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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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Go to the Qt plugin source directory:
cd QT_SRC_PATH\src\plugins\sqldrivers\psqlStart 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 -
libpq-fe.h being in include/libpq
You should use
@“INCLUDEPATH+=c:/psql93_x86/include/libpq”@
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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.proC:\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 -
http://pastebin.com/4cpqVMiN
folder contents -
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! -
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. -
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.
