@Lasith You should open the database only once. Currently you do it each time button is pressed.

Hi,

There's no need for any global objects all the more if you only have one active connection for your application but it's also valid if you are managing multiple connections. The QSqlDatabase class already provides everything you need.

Like written in the documentation, if you are only using one connection, don't give it a name, it will become the default connection and all the SQL related classes will use it by default.

If you have several connections, it's easy to retrieve the one you are interested in by using QSqlDatabase::database.

On a side note, you should properly test the outcome of your open call. Right now it could be failing and you don't care about that possibility.

Put a QSortFilterProxy model in-between. then save from the proxy instead of the main model.

P.S.
connect(currentTableHeader, SIGNAL(sectionClicked(int)), this, SLOT(on_sectionClicked(int))); and void mainWidget::on_sectionClicked(int index) are useless. this is the default behaviour of QTableView, you don't have to implement it manually

@johngod Okay, Thanks, i try it.

http://download.qt.io/official_releases/qt/

You also have the MaintenanceTool that offers that possibility.

@Kushan
basically Oracle supports requests via ODBC driver. So this is more a matter of your DB configuration.

@J.Hilk Thanx alot

Yes $$PWD is the right thing to do

Yes they can, nothing wrong with that. Furthermore, if you write Device1.pri correctly you can include it in Device1.pro so you have code duplication.

Because a project is not only code, you could have other things like unit tests, documentation to generate etc.

Also, I avoid having build artefacts in my sources and do out of source builds to keeps things cleanly separated.

While I'm here, you can use https://github.com/VSRonin/Qt-Model-Serialisation/tree/dev

CsvModelSerialiser modelSaver; modelSaver->setModel(ui->tableWidget_2->model()); modelSaver->setCsvSeparator(" "); QFile mFile("C:/Users/Desktop/Qt/textfiles/test.txt"); modelSaver->saveModel(&mFile);

I built qt and font show up now. Thanks a lot jsulm for the support.

@Ashwinimehra
Hi and welcome
Its outside the scope of Qt but linux does support it
http://www.thegeekstuff.com/2012/04/linux-file-locking-types/

@Sowmiya-R
Ok, that does not happen for me.
Without break point it works correctly here.

I have no idea what could be wrong with your Qt.

Since you are using a clean project to test, i assume is something with your pc or Qt.

Thanks everyone for insight . I have some idea now from where i should start .

main.qml - What is the top level item ? Is it window or Item ?
loginform.qml - What is top level item ? Is it window or Item ?

This is typical issue of object deleted already is getting delete due to parent child relation ship ?

Hi,

Please share me mail mahesh@claysol.com
we have expertise on Qt with C++

Hi,

If you want to mix widgets and QML then you should use QQuickWidget.

Hi everyone!

I've found the problem in my component. I was forgot this line in my constructor:

m_contentItem = Q_NULLPTR;

So, all works fine for now! Thanks all for the help.

@Gluon666
How do you know that A, B and C are equal to 0? If they are, then your program will give error when you click on "calculate" - "Division by zero".
Could you put some debug statements in your code?
Like this:

qDebug() << "A: " << A << "\tB: " << B << "\tC: " << C; delta = ((B * B) - (4 * (A * C)));

@John_A._Myer yes

@joeQ As it turns out, I just tried the opposite. I had one newed Message Box for everything. In the place that had the funny location, I made a separate newed Message Box and it ended up in the correct place - the middle of its parent.

@diredko Why passing it once using a normal function (Q_INVOKABLE) would hurt performance in your opinion? It would certainly be more efficient to have a big list in QML than use a function again and again, and such a list isn't big for modern hardware (couple of hundreds of KBytes maybe). If you can afford to have that list in C++ you should be able to afford to have it in QML, too.

I think the biggest performance obstacle is that the system isn't real-time, QML may do garbage collection and animation isn't fluent. I recommend just testing with the most easy solution in the lowest end hardware it will be run on and deciding after that if it's enough.

Interestingly, if I make the plugin static, it works fine. Only when the plugin is dynamic does this error happen... Very strange.

Hi and welcome to devnet,

Did you install Visual Studio 2015 ? If so did you install the C++ component ?

After a detailed research of various asynchronous techniques such as Promises, Futures, Tasks and Reactive Extensions we came with a new paradigm that solved all our asynchronous problems very elegantly: The Streams Paradigm

It's inspired by the reactive approach, though superior in many aspects such as abstraction, abortion, resumables etc.

It's a completely rethought way of writing declarative code, making complex asynchronous operations and transactions (and probably even concurrency) a piece of cake! Nearly everything can be represented, thus abstracted away by a stream..

UI Elements Sockets Requests (HTTP etc.) Calculations the list goes on...

This way streams become a consistent protocol of asynchronous and concurrent communication between various application components ranging from the UI frontend to the networked backend.

We published the first beta release of a QML implementation with a working example aboard, be sure to check it out!

https://qbeon.github.io/QuickStreams/

I have reported this issue on the Qt bug tracker.
If someone is interested: https://bugreports.qt.io/browse/QTBUG-60738

Hi !
We are a company from Ukraine. We develop different devices include ultrasonic devices.That's why we have experience developing software for microcontrollers STM32 and Qt software. We have experience om Windows Ce embedded. I read that you need only employee job. But I think we can discuss our opportunities.
Thanx a lot,
Sergey

Yes, I did see that example, however how to run it? it builds a library (how do I connect that to a normal app?)
And is that the best way to build an app that heavily relies on the drawn graphics?

@mrjj Thanks, used Schtasks.exe to create task & to run it as admin used shellexecute with verb "runas".

Thanks for the feedback.

@SGaist New output (after getting logged out): https://pastebin.com/yJK4tFeQ

Output of diff dmesgOutputBeforeLogout.txt dmesgOutputAfterLogout.txt: https://pastebin.com/5jGtEiUd (differences between two outputs)

@mrjj , Thanks bud. It worked. You have just made my life easier.

I got it to work with the following line:

obj->setProperty("parent", QVariant::fromValue<QObject*>(viewport));

now everything's fine, anyway.. am I doing everything correctly here?

It's strange that it's not documented

@DougyDrumz said in Can't Cancel Progress Dialog.:

OK. I found it. I was being dumb! I have two flavors of Progress Dialogs. One is inside an App, and the other is standalone, meant to be called form a script. I was looking at the one in the App when I should have been looking at the other one. The standalone one doesn't have have a cancel slot.

Good !

@ganeshkbhat Allowing to load and run 3rd C++ inside your main applications's process is very dangerous and we have not found any easy way to sandbox C++ so far, only just have a few ideas worth trying. I've described this issue here in a little more detail.

@eggbertx said in Trying to create a singleton and getting LNK2019 error:

Sorry, I meant the second code block, not the first. I'm not very familiar with assertions in general, so I've never heard of Q_ASSERT.

The assertion here is only a tool to detect creating more than one instance of the class. Q_ASSERT is a Qt macro for regular debug assertions, it will be removed in release mode, so its purpose (as assertions in general) is to catch programmer errors while debugging. So if you use the class above like this:

Singleton object1; Singleton object2; //< Here the assertion will be tripped and you can catch the error while debugging

Adding the code in the second block fixed the issue.

Do you mean the main window constructor where the connect is made? All code blocks are part of one single example, so I'd expect them to work together only. :)