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Details

Type: Bug
Resolution: Fixed
Priority: P3: Somewhat important
Fix Version/s: 6.6.3, 6.5.6
Affects Version/s: 6.6.2
Component/s: Documentation
Labels:
None

Commits:
b4642eda1e2481822f9a77f02208d4ba77202cc3, 5f8089693 (tqtc/dev), 9bec8a7ef (tqtc/6.6), e2580959d (tqtc/dev), d97ca0f9f (tqtc/6.5), f44feadc6 (tqtc/6.6), e138c01bd (tqtc/dev), 62123a34f (tqtc/6.6), 557731e5c (tqtc/6.5), 625f3c693 (tqtc/dev)

Description

See https://doc.qt.io/qtforpython-6/examples/example_opcua_opcuaviewer.html

Problem 1: Undefined variable

Traceback (most recent call last):
  File "D:\QtSupport\opcuaviewer\mainwindow.py", line 142, in findServers
    self.createClient()
  File "D:\QtSupport\opcuaviewer\mainwindow.py", line 115, in createClient
    QMessageBox.critical(self,  "Failed to connect to server", message)
NameError: name 'message' is not defined
Traceback (most recent call last):
  File "D:\QtSupport\opcuaviewer\mainwindow.py", line 142, in findServers
    self.createClient()
  File "D:\QtSupport\opcuaviewer\mainwindow.py", line 115, in createClient
    QMessageBox.critical(self,  "Failed to connect to server", message)
NameError: name 'message' is not defined

Original C++ code

void MainWindow::createClient()
{
    if (mOpcUaClient == nullptr) {
        mOpcUaClient = mOpcUaProvider->createClient(ui->opcUaPlugin->currentText());
        if (!mOpcUaClient) {
            const QString message(tr("Connecting to the given sever failed. See the log for details."));
            log(message, QString(), Qt::red);
            QMessageBox::critical(this, tr("Failed to connect to server"), message);
            return;
        }
        // ...
    }
}

Python code

    def createClient(self):
        if not self._opcua_client:
            self._opcua_client = self.mOpcUaProvider.createClient(self._ui.opcUaPlugin.currentText())
        if not self._opcua_client:
            qWarning("Connecting to the given server failed. See the log for details.")
            QMessageBox.critical(self,  "Failed to connect to server", message)
            return

        # ...

Problem 2: Crash

Steps to reproduce

Fix the undefined variable above
Ensure that OpenSSL is available in the PATH (required to load the "open62541" plugin)
Run the example and click "Find servers"

The program will soon crash, regardless of whether or not an OPC UA server is running on the local machine.

Note: The C++ version of the example doesn't crash using Qt 6.6.2: It fails gracefully when no server is available, and connects successfully to the server when it is available.