pyQt5 handling multiple windows - pyqt5

Question

A simple issue which I can't fix as I'm pretty newbie in using pyQt...
I have an application which has a window with a QPushButton1 and when it's clicked it opens up a second window with another QPushButton2. What is happening is when I close the second window pressing 'x' and I come back to the first one, if I click again the QPushButton1 the second window does not open. Only when I click one more the QPushButton1 the second window is opened. Maybe I would need to set self.w(second window) = None when the second window close, but I don't know where to put it. Thanks for any help
class MainWindow(QWidget, Ui_f_tabella):
def __init__(self):
super().__init__()
self.setupUi(self)
self.w = None # No external window yet.
self.pb_Ins.clicked.connect(self.inserimento_mat)
def inserimento_mat(self):
if self.w is None:
self.w = InserimentoMateriali()
self.w.show()
self.w.pb_conf.clicked.connect(self.conferma_inserimento_materiali)
else:
self.w.close()
self.w = None # Discard reference, close window.
def conferma_inserimento_materiali(self):
"""Aggiunta nuova risorsa"""
self.data = []
for field in (self.w.lE_descMat, self.w.dSB_pesoSp):
if not field.text():
QMessageBox.critical(
self,
"Errore!",
f"Inserimento non consentito per mancanza di informazioni"
#f"Inserire il valore {field.objectName()}",
)
self.data = None # Reset .data
return
self.data.append(field.text())
if not self.data:
return
rec = self.model.record()
rows = self.model.rowCount()
for column_index, field in enumerate(self.data):
if rec.fieldName(column_index)=="ps_mat":
x = field.replace(",", ".")
field=x
rec.setValue(rec.fieldName(column_index), field)
if(self.model.insertRecord(-1, rec)):
self.model.submitAll()
self.model.select()
QMessageBox.information(self, "Conferma inserimento",
f"Inserimento nuovo materiale effettuato")
self.w.close()
self.w = None
else:
msg="Errore inserimento nuovo materiale: <br> <br>" + self.model.lastError().text()
QMessageBox.critical(self, "ERRORE", msg)
class InserimentoMateriali(QDialog,Ui_InsMateriali):
def __init__(self):
super().__init__()
self.setupUi(self)
app = QApplication(sys.argv)
window = MainWindow()
window.show()
sys.exit(app.exec_())enter code here

Answer 1

The problem is that when closing the window using the system buttons doesn't reset your self.w, so the if self.w is None condition is not met.
A possible solution is to set the DeleteOnClose attribute and connect the destroyed signal to a function that restores the variable.
def inserimento_mat(self):
if self.w is None:
self.w = InserimentoMateriali()
self.w.setAttribute(Qt.WA_DeleteOnClose)
self.w.destroyed.connect(self.resetFlag)
self.w.show()
self.w.pb_conf.clicked.connect(self.conferma_inserimento_materiali)
else:
self.w.close()
def resetFlag(self):
self.w = None