Is this correct, to have a thread calling slot in main process?
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I was getting the following error in Qt5 because my MainWindow dropped a thread that was trying to update a treeview in the main thread.
QObject: Cannot create children for a parent that is in a different thread.So in my thread class (derived from QObject) I have this function which takes the MainWindow object to which the slot will be called.
void MyTest::set_model(MainWindow &mw) { connect(this, SIGNAL(update_tree), mw, SLOT(update_treeview), Qt::QueuedConnection); } void MyTest::update_tree() { std::cout << "update_tree ........" << std::endl; }And in my MainWindow, here is how I pass the MainWindow object to the thread so that it can emit a signal and call a slot in the main thread (TBD: emit signal).
void MainWindow::update_treeview() { std::cout << "calling update_treeview() ..." << std::endl; } MyTest *test = new MyTest; test->set_model(this, tree_model, tree_view); std::thread t(test); t.join();It doesn't yet compile, but am I going about this correctly? My goal is to have the thread pass TreeModel data to the main process so the TreeView can be updated.
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Hi,
If you want a model with thread support, you should check the implementation of
QFilesystemModel. -
The short answer is that ther's a 99.9999% chance what you are doing is wrong.
The model can't be read nor written from a non-gui thread if that model is connected to a view.
The view calls methods from the model directly so any operation on the model from a different thread is a race condition.
The correct way to do it is to emit a signal with the new data from the secondary thread and have the gui thread do the actual update
