gds Works

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# posted by gdys @ 5:00 AM 0 comments

• ValidationRules.CheckRules(PropertyName)
• MarkDirty()
• OnPropertyChanged(PropertyName)

# posted by gdys @ 5:22 PM 0 comments

Continue
This is one of the features I've been looking for in VB .NET and I'm glad they added this functionality. Using this keyword insie the loop allows you to skip and perform the next iteraion. Continue For is used cojunction with For loop and Continue While is use in while loop.

Using
This is for garbage collection where in developer wishes to explicitly clean up the unmanged resources before abandoning an object. The object must implment IDisposable. Please see below for an example:

Public Class Countries
    Inherits Generic.List(Of Country)
    Implements IDisposable

    Public Overloads Sub Add(ByVal CountryName As String)
        Dim itm As New Country
        itm.CountryName = CountryName
        Me.Add(itm)
        Dim i As Integer = Me.Count - 1
        Me.Item(i).IDCountry = Me.Count
    End Sub

    Public Overloads Sub Dispose() Implements IDisposable.Dispose
        ' Do some clean up here
    End Sub
End Class

Dim mCountries As New Countries
' Retrive some data from mCountries
Using (mCountries)
' Manipulate data
End Using

# posted by gdys @ 6:57 PM 0 comments

Global
Points to .NET framework base class library when used. This is useful wherein some of the custom namespace in an assembly has the same namespace in .NET framework base class libraries.

Namespace System.IO
 
    Public Class FileWriter
        Public Shared Sub Write()
            ' Some code here for actual implementation
        End Sub
    End Class
 
End Namespace

Dim fstm as Global.System.IO.FileStream

# posted by gdys @ 10:32 PM 0 comments

Environment: CLSA .NET and Windows Form

The original sample code illustrated the use of Application.IdleSync() to toggle the save button in a BusinessBaseCollection when editing a specific editable object. I've noticed when the mouse is moved the application.IdleSync() handler is triggered and I find it ineffecient.

Trying to find an efficient way, I noticed that BusinessBaseCollection overrides the OnListChanged Event. So I changed my IdleSync handler to OnListChanged.

See below for illustration:

In windows form level, I've created a method name OnListChanged()

Private Sub OnListChanged(ByVal sender As Object, ByVal e As System.ComponentModel.ListChangedEventArgs)
 btnSave.Enabled = mCustomer.IsSavable
 'Add the code for the Broken Rules Error Provider
End Sub

mCustomer = Customers.GetCustomers()
'Needs to be remove first
RemoveHandler mCustomer.OnListChanged, AddressOf OnListChanged
AddHandler mCustomer.OnListChanged, AddressOf OnListChanged

RemoveHandler mCustomer.OnListChanged, AddressOf OnListChanged

# posted by gdys @ 4:22 AM 0 comments

I’ve managed to create my own switchable mechanism in CSLA .NET for editable object. I did tried to implement the original switchable editable object as presented by the author, but it confuses me a lot. As far as I understand to make the editable object switchable from root to child is by putting MarkAsChild() in the constructor of the object. When an editable child object is implemented calling Save() method it would throw an exception because it can’t be save directly. However, if we can manage to change the IsChild property from true to false then there will be no problem. But IsChild is a read only property.

So out of curiosity, I tried to use reflection to change the mIsChild of type boolean private variable to false to behave as a root object and setting it to true to behave as a child object and it works. So I decided to combine the implementation of child and root object rather than implementing switchable object.

When calling Save() method in:

• Root – it invokes DataPortal_Update()
• Child – it invokes the Friend Sub Update()

Public Sub ToRoot(ByVal o As Object)

    Dim t As System.Type

    t = o.GetType().BaseType()

    If String.Compare(t.Name, "BusinessBase", True) > 0 Then
        Throw New Exception("Not a CSLA object")
    End If

    Dim fi As FieldInfo = t.GetField("mIsChild", _
            Reflection.BindingFlags.NonPublic Or BindingFlags.GetField Or BindingFlags.Instance _
            Or BindingFlags.FlattenHierarchy Or BindingFlags.CreateInstance _
            Or BindingFlags.SetField)

    If fi Is Nothing Then
        Throw New Exception("Unable to resolve CSLA object info")
    End If

    Dim IsChild As Boolean = fi.GetValue(o)

    If Not IsChild Then
        Throw New Exception("The object is already in Root")
    End If

    fi.SetValue(o, False)

End Sub

Public Sub ToChild(ByVal o As Object)

    Dim t As System.Type

    t = o.GetType().BaseType()

    If String.Compare(t.Name, "BusinessBase", True) > 0 Then
        Throw New Exception("Not a CSLA object")
    End If

    Dim fi As FieldInfo = t.GetField("mIsChild", _
            Reflection.BindingFlags.NonPublic Or BindingFlags.GetField Or BindingFlags.Instance _
            Or BindingFlags.FlattenHierarchy Or BindingFlags.CreateInstance _
            Or BindingFlags.SetField)

    If fi Is Nothing Then
        Throw New Exception("Unable to resolve CSLA object info")
    End If

    Dim IsChild As Boolean = fi.GetValue(o)

    If IsChild Then
        Throw New Exception("The object is already in Child")
    End If

    fi.SetValue(o, True)

End Sub

1. Get a clone copy of the editable object from the root collection
   
   eobjName = DirectCast(Me.BindingContext(mNameCol.Current, eobjName).Clone()
   
2. Call ToRoot()
   
   ToRoot(eobjName)
   
3. Do necessary things to the root object you can also invoke Save() method
   
   'Do something with root object and save changes
   eobjName.Save()
   
4. Call ToChild(), to reset the original setting
   
   ToChild(eobjName)
   
5. Update root collection to update the content of it using the clone Object. Since there is no available method in BusinessBaseCollection to update the content of the collection you need to create a method UpdateCollection in the root collection

   
   Friend Sub UpdateCollection(ByVal o as eobjNameType)
   Dim i as Integer
   For i = 0 To List.Count - 1
     If DirectCast(List.Item(i), eobjNameType).Equals(o) Then
       List.Item(i) = o
       Exit For
     End If
   Next i
   End Sub

I know this is a hack version against the original implementation and I guess a lot of you guys will object on what I did. =)

# posted by gdys @ 5:18 AM 0 comments