Save problem with custom delegate

[Banjo]

Hello
I have written a custom delegate to display dates in a particular format and then save them when entered this way. The problem is that it appears to work randomly. Either it saves the date correctly to a sqlite3 database or I get a messagebox pop up with a Microsoft 'python.exe has encountered a problem' message. I also get 'Process terminated with an exit code of -1073741819' in the IDE OS Commands tab (Wing).

This is the setModelData function from the delegate.

def setModelData(self, editor, model, index):
	    if index.isValid():
		if DATATYPE[self.parent.dataType] == 'SURVEY' and index.column() in [7, 8]:
		    model.setData(index, QVariant(QDate.fromString(str(editor.text()), 'd/M/yyyy')))
		else:
		    QSqlRelationalDelegate.setModelData(self, editor, model, index)

def setModelData(self, editor, model, index):
	    if index.isValid():
		if DATATYPE[self.parent.dataType] == 'SURVEY' and index.column() in [7, 8]:
		    model.setData(index, QVariant(QDate.fromString(str(editor.text()), 'd/M/yyyy')))
		else:
		    QSqlRelationalDelegate.setModelData(self, editor, model, index)

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Thanks in advance.