Why QFileDialog::selectFile doesn't work? - c++

Question

I am using Qt 5.12 and trying to write test (using QTest) for opening of project stored in some xml format.
In test I use QTimer::singleShot to wait QFileDialog to appear as proposed in QT close window by QTest in locked thread.
The problem is that QFileDialog::selectFile doesn't select anything. This means that OK button is not active, so I can't click on it in my test.
I assume in the following example that full path to file is /tmp/project.xml. Notice that QFileDialog::setDirectory works great: when the following example starts, you are in /tmp dir instead of /.
#include <QApplication>
#include <QFileDialog>
#include <QTimer>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
QTimer::singleShot(300, []() {
QWidget* window = nullptr;
while (!window) {
window = qApp->activeModalWidget();
}
QFileDialog* fd = qobject_cast<QFileDialog*>(window);
fd->setDirectory("/tmp");
fd->selectFile("project.xml");
});
QString path = QFileDialog::getOpenFileName(nullptr, "Open Project",
"/", QString(),
nullptr, QFileDialog::DontUseNativeDialog);
}

Answer 1

The function selectFile didn't work because of the file name text box (lineEdit) is focused. This behavior comes from the implementation of QFileDialog::selectFile() :
void QFileDialog::selectFile(const QString &filename)
{
// ... function body
//Put the filename into the lineEdit when :
//1. The dialog is not visible or
//2. The lineEdit is not focused.
if (!isVisible() || !d->lineEdit()->hasFocus())
d->lineEdit()->setText(index.isValid() ? index.data().toString() : fileFromPath(d->rootPath(), filename));
}
To make the program works, there are two ways :
Put the file name directly in the text box
Give the focus away then call selectFile
fd->setDirectory("/tmp");
QLineEdit * lineEdit = qobject_cast<QLineEdit*>(fd->focusWidget());
if( lineEdit ){
//Method 1
lineEdit->setText("project.xml");
//Method 2
lineEdit->nextInFocusChain()->setFocus();
fd->selectFile("project.xml");
}else { //no lineEdit focus found
fd->selectFile("project.xml");
}