Update QLabel in slots

[akshaybabloo]

I have a label on status bar which should update a text depending on text received in a custom slot. I can add a text to this label from the constructor.

The code for the slot is:

void StatusBarIndicator::receiveServerStatusLabel(const QString &text) {
    qInfo() << text;
    ui->serverStatusLabel->setText(text);
}

This slot can receive the text but it's not updating the label. Looking at other threads I have tried the following:

1. Add repaint() after setText()
2. Add clear() before setText()
3. Add clear() before setText() and the add repaint()
4. Add update() after setText()
5. All the combinations above and then add QCoreApplication::processEvents()

None of the above points worked. Is there any way to update the text?

Update

Just made my code public - https://github.com/akshaybabloo/DataLogger. I am using CMake.

Double click on any of the list item, this should open a window. Click on - start server - button. That button should update the label.

[Cobra91151]

I have checked your repository on GitHub and fixed the issue.

Your code:
ui->statusbar->addPermanentWidget(new StatusBarIndicator, 1); // here you create instance of StatusBarIndicator, also new StatusBarIndicator creates a memory leak, do not use it like that anywhere.

But

auto *indicator = new StatusBarIndicator; // here your create new instance again
connect(this, &Logger::emitServerStatusLabel, indicator, &StatusBarIndicator::receiveServerStatusLabel);

My code:

auto *indicator = new StatusBarIndicator(this);
ui->statusbar->addPermanentWidget(indicator, 1);
connect(this, &Logger::emitServerStatusLabel, indicator, &StatusBarIndicator::receiveServerStatusLabel);

Screenshot:

[jsulm]

@akshaybabloo said in Update QLabel in slots:

None of the above points worked

None of that should be necessary.
Did you make sure the slot is actually called?
If it is called - what does text contain?

[akshaybabloo]

@jsulm for now the code just emits a string:

void Logger::on_serverButton_toggled(bool checked)
{
    if (checked){
        emit emitServerStatusLabel("server running on 127.0.0.1:1000");
    } else {
        emit emitServerStatusLabel("");
    }
}

And yes, the slot does receive the text.

[JonB]

@akshaybabloo
As @jsulm wrote, all should already be working.
At a guess: inside class StatusBarIndicator, what does ui (and ui->serverStatusLabel) refer to? Is it possible it's not the label you think it is? Put some other text into the label first, then qInfo() << ui->serverStatusLabel->text(); before setting it anew in the slot? Is the signal connected to the correct instance? Try with something else?

[akshaybabloo]

@JonB @jsulm I have updated my question with the link to the repository

[Cobra91151]

I have checked your repository on GitHub and fixed the issue.

Your code:
ui->statusbar->addPermanentWidget(new StatusBarIndicator, 1); // here you create instance of StatusBarIndicator, also new StatusBarIndicator creates a memory leak, do not use it like that anywhere.

But

auto *indicator = new StatusBarIndicator; // here your create new instance again
connect(this, &Logger::emitServerStatusLabel, indicator, &StatusBarIndicator::receiveServerStatusLabel);

My code:

auto *indicator = new StatusBarIndicator(this);
ui->statusbar->addPermanentWidget(indicator, 1);
connect(this, &Logger::emitServerStatusLabel, indicator, &StatusBarIndicator::receiveServerStatusLabel);

Screenshot: