Still confused when passing parameters to subclass/signal-slot

[JuanW]

I am a newbie in Python/PyQt and I humbly ask for help.

I have a form where user can add a new record by clicking Add button and user can update the record by double clicking on the QTableView. The add and update call the same function "open_detail()" which then open another window "UnitDetail".

My problem is on the "update" -- I passed QModelIndex from the double click event. I can see row/column on the open_detail(). However, when I passed the index to UnitDetail it has None value.

Where is the logic error? Thank you.

My code snippet:

class Unit(QtWidgets.QWidget):
   def __init__(self):
        super(Unit, self).__init__()
        self.ui = Entity_Form()
        self.ui.setupUi(self)
        self.dtl = Unit_Form()

        self.ui.lblHeader.setText('Your Units')
        self.ui.btnAdd.setText('Add a Unit')
        self.ui.stackedWidget.setCurrentWidget(self.ui.pgList)
        
        self.ui.btnAdd.clicked.connect(self.open_detail)
        self.ui.tvTable.doubleClicked.connect(self.open_detail)

        self.model = QSqlRelationalTableModel(db=self.db)
        self.model.setTable("Unit")
        self.ui.tvTable.setModel(self.model)
        self.ui.tvTable.horizontalHeader().setStretchLastSection(True)      
        self.model.select()

    def open_detail(self, index):
        self.index = index
        self.dtl = UnitDetail(self, index=None)
        self.dtl.show()

class UnitDetail(Unit_Form, QtWidgets.QWidget):
    def __init__(self, parent, index):
        super().__init__()
        self.parent = parent
        self.setupUi(self)
        if index == None:
            self.btnDelete.hide()
        else:
            row=index.row()
            model=parent.model()
            print(f'row {row}')

[jeremy_k]

@JuanW said in Still confused when passing parameters to subclass/signal-slot:

@jeremy_k,
Thank you so much, it works. I though the "None" in parameter index=None means to set the index value as None when I do not pass any value to it.

Do that for the declaration rather than invocation.
EG

class Foo:
    def __init__(self, index = None): 
        pass

Foo()  # index is None
Foo(0) # index is 0

[jeremy_k]

@JuanW said in Still confused when passing parameters to subclass/signal-slot:

I am a newbie in Python/PyQt and I humbly ask for help.

I have a form where user can add a new record by clicking Add button and user can update the record by double clicking on the QTableView. The add and update call the same function "open_detail()" which then open another window "UnitDetail".

My problem is on the "update" -- I passed QModelIndex from the double click event. I can see row/column on the open_detail(). However, when I passed the index to UnitDetail it has None value.

Where is the logic error? Thank you.

My code snippet:

class Unit(QtWidgets.QWidget):
    def open_detail(self, index):
        self.index = index
        self.dtl = UnitDetail(self, index=None)
        self.dtl.show()

Note the index = None in the UnitDetail constructor invocation.

[JuanW]

@jeremy_k ,
I did that because "add" button also call open_detail() with no index available. Any other clue?

[jeremy_k]

@JuanW said in Still confused when passing parameters to subclass/signal-slot:

However, when I passed the index to UnitDetail it has None value.

@JuanW said in Still confused when passing parameters to subclass/signal-slot:

@jeremy_k ,
I did that because "add" button also call open_detail() with no index available. Any other clue?

If you pass index = None, index will be None. I suspect that in open_details(), the intention is to invoke UnitDetails(self, index), or UnitDetails(self, index=index).

[JuanW]

@jeremy_k,
Thank you so much, it works. I though the "None" in parameter index=None means to set the index value as None when I do not pass any value to it.

[jeremy_k]

@JuanW said in Still confused when passing parameters to subclass/signal-slot:

@jeremy_k,
Thank you so much, it works. I though the "None" in parameter index=None means to set the index value as None when I do not pass any value to it.

Do that for the declaration rather than invocation.
EG

class Foo:
    def __init__(self, index = None): 
        pass

Foo()  # index is None
Foo(0) # index is 0