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• 

  How to create the plugin of MYSQL for Qt
  • BlackStar

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  @flydragon

  Do not duplicate posting because you do not get an answer immendiately.

  [edit:koahnig see https://forum.qt.io/topic/82629/why-qsqlquery-exec-exit-failed ]

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  Reporting inappropriate content on the forums
  spam • • Eddy

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  Thank you for the report. I have banned the user, which got rid of the spam posting. Not a loss, as this user did not post any other content on the site. Just deleting this one posting was not possible.

  Thanks for reporting this.

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  Unsolved cannot find -lGL Error
  • eswar

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  @eswar
  After you have verified which distro you have as per @aha_1980's suggestion...

  Assuming you do have a locate with an up-to-date database (sudo updatedb), copy & paste:

  locate libGL.so

  I'd expect it to come up with something, probably /usr/lib/x86_64-linux-gnu/libGL.so. Make sure it does, and whatever path is included on your link path.

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  Unsolved Why are apps generally unavailable for desktops?
  • alexsu

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  As apps are useless on a desktop where you can get real applications?

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  Solved Cant connect to mysql database: QMYSQL driver not loaded
  • cdwijs

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  @JonB You're right I didn't think about the drive

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  Solved Connecting several readyRead() signals to one slot (QSerialPort)
  signals & slots qserialport • • smnsmn

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  @smnsmn said in Connecting several readyRead() signals to one slot (QSerialPort):

  Qt::QueuedConnection
  The slot is invoked when control returns to the event loop of the receiver's thread. The slot is executed in the receiver's thread.

  This is for queued connections which are not used by default for signals/slots in same thread. You really need to differentiate between connections in same thread and such between different threads.

  "Can signal thread == receiver thread?" - sure, it is like this most of the time. Only if you use more than one thread you can have signals and slots in different threads. For signals and slots in same thread queued connection is NOT used, unless you tell Qt to do so (last parameter in connect() call).

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  Solved reading file line by line crashes
  qt 4.8 qtextstream readline • • mourad_bilog

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  Finally I changed reading mode to read directly from the data file. It's most faster and just I was care to encode data when reading to keep special charcatars.

  Thanks all for your ideas

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  Unsolved Capture 3 keys together on QGraphicsItem
  • Uday More

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  Unsolved Warnings: Feast or Famine
  mac qmake warning • • wumpus7

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  Hi @wumpus7,

  Nothing I do seems to affect the warnings produced in the Compile Output (and thus Issues) panes when I clean all, run qmake, and run.

  QMAKE_CXXFLAGS is already the right (and only) way. You need to check the compile output, if the flags are really passed to the compiler - because the compiler generates the warnings.

  Turning off the ClangCodeModel (Qt Creator>About Plugins...) kills off the inline warnings in the source editor, but has no other obvious effects.

  And that's exactly what I wrote in my post yesterday. If you want to keep the inline annotations, you have to enable Clang again and then modify the settings in Tools > Options > C++ > Code Model > Clang Code Model.

  Modifying the 'Diagnostic Configuration' (Custom Settings on the Analyzer Configuration, reached from Analyze>Clang Tidy and Clazy...) and files to be analyzed removes/add warnings as expected when running the analyzer, but has no effect on the inline warnings in the source editor.

  And that's expected, as it only influences the static analyzer you can call by Analyze > Clang Tidy and Clazy...

  So, to keep it short:

  Compiler warnings are configured with QMAKE_CXXFLAGS Inline annotations are configured with Tools > Options > C++ > Code Model > Clang Code Model

  Does that help you?

  Edit:

  'Weverything' is a page about how this is a terrible switch to use on a regular basis. It's the default setting for the analyzer.

  You can always change that The analyzer is thought to bring up any issue you code may have, much more pedandic than a compiler does. That's the whole point of an analyzer.
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  Solved how do i perform autoscroll in QTablewidget ? so it'll scroll down to bottom with a constant speed
  • Redho B N

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  @VRonin WOW YOURE A GOD!!! THNX ALOTT!!!

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  Unsolved Saving the total number of users
  • TheDomesticUser

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  @TheDomesticUser
  Hi and welcome to the forums.
  To start using Qt and database
  https://doc.qt.io/qt-5/database.html
  Please note you must add
  QT += sql
  to your .pro file and run qmake from build menu for it to know the classes.

  You must know a bit of SQL to use them.

  small sample

  bool createConnection() { QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE"); db.setDatabaseName(":memory:"); // open db in memeory // use this to have a file db.setDatabaseName("c:\\folder\\test.db"); if (!db.open()) { QMessageBox::critical(0, qApp->tr("Cannot open database"), "Click Cancel to exit.", QMessageBox::Cancel); return false; } QSqlQuery query; // this creates a table with firstname, lastname and a number qDebug() << "table:" << query.exec("create table person (id int primary key, " "firstname varchar(20), lastname varchar(20), num int )"); // put some data in table query.exec("insert into person (firstname , lastname, num) values('Dennis', 'Young','1')"); query.exec("insert into person values(102, 'Christine', 'Holand','2')"); query.exec("insert into person values(103, 'Lars junior', 'Gordon','4')"); query.exec("insert into person values(104, 'Roberto', 'Robitaille','5')"); query.exec("insert into person values(105, 'Maria', 'Papadopoulos','3')"); return true; } ---- to read from it, you can use QSqlQuery QSqlQuery query("select * from person;"); or have a look at the models ( which i think fit your case fine) https://doc.qt.io/qt-5/qsqlquerymodel.html https://doc.qt.io/qt-5/qsqlrelationaltablemodel.html
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  Unsolved QTimer seems to just stop
  • acs-sharp

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  @SGaist said in QTimer seems to just stop:

  Do you have your device going to sleep ?

  No--its incapable of this :-)

  Do you have any other application doing something ?

  There are other applications on the system though afaict they are sleeping most of the time.

  What are you doing in the slot connected to that timer ?

  It updates displayed content in various widgets (labels,spinbox, LCDNumber,, ComboBox). I've looked over these for anything that might block (no obvious candidates), and tried commenting them out one by one, but the problem persists. The data (array of integers) it accesses does not entail I/O, but it is memory shared with another thread--the slot handler reads only.

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  Unsolved How to create a child-toolwindow for QOpenGLWindow
  • Joe Malik

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  Can you show how you are handling these two widgets ?

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  Unsolved QAudioDeviceInfo misbehaving in Windows 10
  • CentralScrutinizer

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  Hi,

  Are you using windeployqt to put together the dependencies of your application ?
  Did you deploy the QtMultimedia plugins ?

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  Unsolved QGraphicScene
  • grsabourin

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  Hi,

  Shouldn't you breathe use QGraphicsScene::fitInView ?

• 

  This topic is deleted!
  • TheDomesticUser

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• 

  Unsolved How to navigate to old QML API
  • TopNotch_Mach07

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  Hi,

  What version of Qt are you using ?

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  Unsolved how do i know QTcpSocket signal bytesWritten( qint64 bytes ) stand for which when serveral object called write(..) function with same bytes to write?
  • HelloQt

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  In that case you should rather abstract that part away. If these object don't need to survive long terms, why not just have a queue of data to send ? That way you pass around a controller class to which your various object enqueues these data and the controller will write to the socket.

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  Unsolved Using QSerialPort in multi widget application
  • viniltc

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  hI
  Also, im a little concerned by sharing the serial idea.
  Its fine for writing to it, however, if you connect say 3 other classed to
  readyRead() signal, they all get the signal but whom of them will then read the data ?
  and how will you know if that class was the intended receiver of the data?

  It would help if you explained more what the app does and its intended design.

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  Unsolved My first Qt socket programming program
  • tomy

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  Hi,

  How are you using them ?

  Note that you should use the reply not the request for the readyRead.

• 

  Unsolved TLS initialization failed on Qt windows programm
  • msauer75

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  Hi,

  Did you add the folder containing the OpenSSL dlls to the PATH environment variable in the Run part of the Project panel ?

• 

  Unsolved array append to scatter chart
  • MohsenNz

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  @MohsenNz
  Read https://www.qtcentre.org/threads/69429-SOLVED-QLineSeries-extremely-slow, and the OP's solution? Do you create the QScatterSeries and then add that?

• 

  Solved Problem building qt static on win 10
  • ChortleMortal

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  @Christian-Ehrlicher
  OK. My mistake. I deleted the sources using the maintenance tool, deleted what was left in the Src directory, downloaded, and executed the two commands - and it built perfectly. So I must have done something wrong along the way. I see now the the qmake_pch.pch is build in the configure stage not the nmake stage, so it must have been me who built it with the wrong compiler.

  Apologies for wasting your time. I should have had the sense to rebuild from scratch without needing to be prompted.

• 

  Unsolved Beautyfier error
  • gabor53

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  Hi
  Not sure what it means by that.
  Please try this config. and see.

  --style=kr --indent=spaces=4 --align-pointer=name --align-reference=name --convert-tabs --attach-namespaces --max-code-length=100 --max-instatement-indent=120 --pad-header --pad-oper

  I have not seen any external formatters for QML but I think the build in works pretty ok ?

• 

  Unsolved Build Win32 desktop apps for Windows 10 ARM64
  • alexenv

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  @alexenv

  You want to checkout this https://doc.qt.io/qt-5/build-sources.html

  As soon as you have a cross-compiler for a host to another platform you can basically compile Qt source. This will allow you to use Qt creator on your host and cross-compile for your target platform. Currently I am using Windows 10 64 bit and I am cross-compiling for Android.

  You can cross-compile on windows also for some embedded linux devices, when you have found a cross-compiler for linux working on windows. By stating that I am typically suggesting to use linux host in virtual box and cross-compile on linux for embedded linux. However, this is more how much pain you are willing to tolerate.

  Cross-compiling Qt source is basically generating a qmake which will be only suitable for your host and hold all the required settings for each cross-compiling run of your application. The change of toolchains within Qt creator is typically a couple of clicks and you are ready to recompile your application for the next target platform.

• 

  Unsolved QSortFilterProxyModel drag/drop issue...
  • Dariusz

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  @Dariusz
  This: https://forum.qt.io/topic/100194/how-to-show-root-directory-in-qfilesystemmodel/8
  was the post I had vaguely recalled. It was indeed QFileSystemModel. The OP concluded with

  i will have to use QSortFilterProxyModel then..

  Have a read, I don't know whether it relates to your situation.

• 

  This topic is deleted!
  • ChortleMortal

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  Unsolved Absolute widget postion on screen
  • Zgembo

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  @Zgembo
  hi, take a look at the mapToGlobal function

  https://doc.qt.io/qt-5/qwidget.html#mapToGlobal

  should do what you want it to

• 

  The procedure entry point cound not be located in the dynamic link library
  • za83

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  I confirm dll libraries from C:\Qt{version}\mingw{version}\bin make Qt desktop app work.

• 

  Unsolved Truncated labels in Y-axis of QChartView
  qtcharts qchartview qvalueaxis • • PauloCarvalhoRJ

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• 

  Unsolved Catching unix interrupt signal on console application when debugging with QtCreator
  • Damien

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  @Damien
  Qt Creator (I don't use it, so don't ask me for more information!) is trapping this for you to be helpful :) IIRC, gdb stops on a signal and then you can either proceed re-raising the signal or ignoring the signal, which sounds a bit like what you say F5 is doing. Have a look at https://stackoverflow.com/questions/19409573/qt-creator-stops-on-linux-signal to see if the setting mentioned there helps you? Or don't press F5! :)

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  Unsolved Write at the beginn of a File (.py)
  • NotYourFan

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  @J.Hilk
  Lol! :) OK, I commented on that earlier, far be it for us to disagree with the venerable @VRonin :) Anyway, the OP can do it either way as he sees fit.

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  Solved How to create a QByteArray to send in QSerialPort
  qserialport qbytea struct • • Dooham

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  @Dooham You're OK, you are not the first (or the last) here to ask/state this! :)

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  Solved linker errors on all objects from Qt libraries after updating Qt
  • Hasan Al-Baghdadi

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  Where did you modify that environment variable ?

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  Solved [Translations] Can't go back to english translation once i switch
  • nwoki

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  @SGaist Yeah, i need to reload the tr strings as defined as the sourceText in order for it to work. In the end, I opted for a you have to restart the application in order for changes to take effect and load the required/desired language on startup. Saved me having to reset text for all my non .ui based components and writing a bunch of extra code to do that.

• 

  Unsolved how to change the line edit value into time format?
  • Redho B N

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  @Redho-B-N
  First, be aware there is a Qt widget QTimeEdit, https://doc.qt.io/qt-5/qtimeedit.html. However, that effectively displays a "time of day", whereas I think your need is for a time duration instead.

  You can see this discussed in an old post on this forum, https://forum.qt.io/topic/19617/how-to-implement-a-widget-for-durations-similar-to-qtimeedit. Unfortunately the link for example code for a QTimeSpan there does not seem to point to anything which works. But the sentiment is correct: you need to roll your own, using a QLineEdit or QSpinbox. Your code must implement the necessary addition logic to convert to hours + minutes, as necessary.

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  Unsolved Using QCA Encrypt Library with Qt >5
  • Hoehli

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  @SGaist said in Using QCA Encrypt Library with Qt >5:

  Might be a silly question, but are you sure you are linking to the right version of OpenSSL ?

  Yes, think so :D. I included C:/openSSL32 for 32-bit, and C:/openSSL64 for 64-bit, that's the path I put my compiled openSSL.

  To compile openSSL (version 1.0.2r) I used MSYS2 and followed this discription. The minGW compiler I used was the one, shipped with QT at: c:/Qt/Tools/mingw530_32 for 32-bit and C:/Qt/Tools/mingw730_64.

  Configured the openSSL with the perl script with this options:

  ./Configure mingw shared no-idea no-mdc2 no-rc5 --prefix=/c/openSSL32

  and for 64-bit:

  ./Configure mingw64 shared no-idea no-mdc2 no-rc5 --prefix=/c/openSSL64

  Between those two steps I restarted MSYS2 and reconfigured the PATH variables to the corresponding minGW compiler.

  I also tried the mingw-w64 compiler (he didn't made it).

  You might be hitting a cmake cache entry.

  32-bit version: https://pastebin.com/2VYa47f0
  64-bit version: https://pastebin.com/4x0Sn5Xm

  If I'm comment the line 5810 (of qca-ossl.cpp - Version 2.1.3 of the QCA) out, the dll's are build and it's working (somehow but probably unstable).
  Thanks for the support! I appreciate.

  Edit:

  I had a deeper look into the CMakeCache files:
  at the 64bit-version i changed the Value for LIB_EAY from C:\Program Files (x86)\Intel\iCLS Client\libeay32.dll, to C:\Program Files\Intel\iCLS Client\ssleay32.dll.

  This reduced the undefined reference errors, now I only get the same error as for the 32-bit version at line 5810.
  YAY -> one step away :D

  man, that's pain on windows... on Arch Linux QCA compiled "out of the box"...

  Edit2:
  tried the current master branch of openSSL (1.0.2s) still the same error.

• 

  Solved CanOpen device EDS file to ObjectDictionary class
  can bus qml • • Babs

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  @mrjj thank you for you response. My further goal is to expose all this data to a qml application that will allow me to configure my devices correctly. For know i'll try what you suggested.

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  Unsolved program unexpectedly finished
  • rahulvishwakarma

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  @rahulvishwakarma You should use debugger to see where and when exactly this happens. It looks like a pointer is invalid.

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  Unsolved win10 firewall cause network connection failed
  • dmnc

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  @hskoglund Thanks for your advice, I tested it, but it is invalid for my situation ,any other suggestion?