Class with combobox options

Question

Hallo,

I am trying to make a class object which shows a options in a combobox and takes a parameters according to that object selection.

Lets say I have an object or class called Box, I want to show some options in a Combobox, for example one to calculate Area and other for Volume, etc and selected option should be calculated.

Also is there a possibility to populate the textbox controls on the form according to the object inputs needed? or it is only done by hiding and unhiding?

Public Class Box

Public Property Length as Double
Public Property Width as Double
Public Property Height as Double

Public Readonly Property Volume as double
Public Readonly Property Area as double
Public Readonly Property Other as double

End class

Thanks

Answer 1

@Hobbyist_programmer

In regards to CatProduct, I left that out but Visual Studio can auto create it for you although here it is in the code below. Concerting unique properties, the base Product class should have all properties even if not used for some products.

Public Class CatProduct  
    Public Property Category As Category  
    Public Property List As List(Of Product)  
End Class  

Think of when a database is properly designed for orders as shown below. Perhaps some orders don't use discount or some products don't use discontinue. It's incorrect to stored some product types differently instead in this type of situation the property is empty in both cases, no harm no foul.

But if you want to break the rules you can by using base classes and overridable properties as per below.

Visuals

Base class

Public Class Base  
    Public Property Id() As Integer  
    Public Overridable Property Name() As String  
End Class  

Revised Product class

Public Class Product  
    Inherits Base  
    Implements INotifyPropertyChanged  
  
    Private _name As String  
    Private _category As Category  
    Private _price As Decimal  
    Private _quantity As Integer  
  
    Public Overrides Property Name() As String  
        Get  
            Return _name  
        End Get  
        Set  
            _name = Value  
            OnPropertyChanged()  
        End Set  
    End Property  
  
    Public Property Category() As Category  
        Get  
            Return _category  
        End Get  
        Set  
            _category = Value  
            OnPropertyChanged()  
        End Set  
    End Property  
  
    Public Property Price() As Decimal  
        Get  
            Return _price  
        End Get  
        Set  
            _price = Value  
            OnPropertyChanged()  
        End Set  
    End Property  
  
    Public Property Quantity() As Integer  
        Get  
            Return _quantity  
        End Get  
        Set  
            _quantity = Value  
            OnPropertyChanged()  
        End Set  
    End Property  
  
    Public Overrides Function ToString() As String  
        Return $"{Name} {Price}"  
    End Function  
  
    Public Event PropertyChanged As PropertyChangedEventHandler Implements INotifyPropertyChanged.PropertyChanged  
    Protected Overridable Sub OnPropertyChanged(<CallerMemberName> Optional propertyName As String = Nothing)  
        PropertyChangedEvent?.Invoke(Me, New PropertyChangedEventArgs(propertyName))  
    End Sub  
  
End Class  

Other class with all properties

For above but includes cost while cost should truly be in the classes above.

Public Class SomeOther  
    Inherits Product  
  
    Private _cost As Integer  
  
    Public Property Cost() As Integer  
        Get  
            Return _cost  
        End Get  
        Set  
            _cost = Value  
            OnPropertyChanged()  
        End Set  
    End Property  
  
End Class  

Answer 2

Hallo Karen, What if i have some properties are common (like cost , quantity ) and some unique properties for the products?

I get CatProduct not defined and results as error.