How to get all properties of an object and its sub objects

Question

Hi,

I have a similar question to this one except I need to loop all the sub objects and change the property to read-only

Please check my code below. This one loop only the main object. When I tried to loop its sub objects, I got an overflow.

Thanks.

Public Class ReadOnlyTypeDescriptor 
    Inherits CustomTypeDescriptor 
    Private mComponent As Object 

    Public Sub New(ByVal component As Object) 
        MyBase.New(TypeDescriptor.GetProvider(component).GetTypeDescriptor(component)) 
        mComponent = component 
    End Sub 

    Public Overloads Overrides Function GetProperties(ByVal attributes As Attribute()) As PropertyDescriptorCollection 
        Dim inPdc As PropertyDescriptorCollection = MyBase.GetProperties(attributes) 

        Dim pdcs As PropertyDescriptor() = New PropertyDescriptor(inPdc.Count - 1) {} 
        For i As Integer = 0 To pdcs.Length - 1 
            If inPdc(i).IsReadOnly Then 
                pdcs(i) = inPdc(i) 
            Else 
                pdcs(i) = New ReadOnlyPropertyDescriptor(inPdc(i)) 
            End If 
        Next 

        Return New PropertyDescriptorCollection(pdcs, True) 
    End Function 

    Public Overloads Overrides Function GetProperties() As PropertyDescriptorCollection 
        Return GetProperties(Nothing) 
    End Function 

    Private Class ReadOnlyPropertyDescriptor 
        Inherits PropertyDescriptor 
        Private mParent As PropertyDescriptor 

        Public Sub New(ByVal parent As PropertyDescriptor) 
            MyBase.New(parent, New Attribute() {ReadOnlyAttribute.Yes}) 
            mParent = parent 
        End Sub 

        Public Overloads Overrides Function CanResetValue(ByVal component As Object) As Boolean 
            Return False 
            ' Read Only 
        End Function 

        Public Overloads Overrides ReadOnly Property ComponentType() As Type 
            Get 
                Return mParent.ComponentType 
            End Get 
        End Property 

        Public Overloads Overrides Function GetValue(ByVal component As Object) As Object 
            Return mParent.GetValue(component) 
        End Function 

        Public Overloads Overrides ReadOnly Property IsReadOnly() As Boolean 
            Get 
                Return True 
            End Get 
        End Property 

        Public Overloads Overrides ReadOnly Property PropertyType() As Type 
            Get 
                Return mParent.PropertyType 
            End Get 
        End Property 

        Public Overloads Overrides Sub ResetValue(ByVal component As Object) 
            ' Read Only 
        End Sub 

        Public Overloads Overrides Sub SetValue(ByVal component As Object, ByVal value As Object) 
            ' Read Only 
        End Sub 

        Public Overloads Overrides Function ShouldSerializeValue(ByVal component As Object) As Boolean 
            Return mParent.ShouldSerializeValue(component) 
        End Function 
    End Class 
End Class 

Answer 1

If you have objects with circular references, you might be visiting properties more than once.

In cases like this, I always find ways to 'mark' which items I've visited before, an idea which is commonly used when traversing graphs.

Answer 2

Thanks Charlie for your respond. Sorry for the late reply. I've been posting at so many boards and kinda lose track.

Let's skip the overflow issue. I have a class with many property class. The code that I posted can only wrap the main class and modify its properties' attribute to readonly {ReadOnlyAttribute.Yes}, but nothing happen with the property that's a class data type. Here's my sample code. To run the code, add a form to your project and copy paste the entire code below. Remember to add System.Design reference

Imports System.Reflection
Imports System.ComponentModel
Imports System.Windows.Forms.Design

Public Class MyForm
    Private item As ClassToWrap
    Private cloneVersion As ReadOnlyTypeDescriptor

    Private Sub Form_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

        item = New ClassToWrap
        item.A = 8
        item.B = 12
        item.MyOtherClass = New AnotherClass
        item.MyOtherClass.Name = "My name"
        cloneVersion = New ReadOnlyTypeDescriptor(item)

        PropertyGrid1.Enabled = True
        PropertyGrid1.SelectedObject = item

    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        PropertyGrid1.SelectedObject = cloneVersion
    End Sub

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        PropertyGrid1.SelectedObject = item
    End Sub

End Class

Public Class ClassToWrap
    Private itemA As Integer
    Private itemB As Integer
    Private itemString As String
    Private _editor As String
    Private comp As Object
    Public Property A() As Integer
        Get
            Return itemA
        End Get

        Set(ByVal value As Integer)
            itemA = value
        End Set
    End Property

    Public Property B() As Integer
        Get
            Return itemB
        End Get

        Set(ByVal value As Integer)
            itemB = value
        End Set
    End Property

    Public Property Name() As Integer
        Get
            Return itemString
        End Get

        Set(ByVal value As Integer)
            itemString = value
        End Set
    End Property

     _
    Public Property MainEditor() As String
        Get
            Return _editor
        End Get
        Set(ByVal value As String)
            _editor = value
        End Set
    End Property

    Private _myOtherClass As AnotherClass
    Public Property MyOtherClass() As AnotherClass
        Get
            Return _myOtherClass
        End Get
        Set(ByVal value As AnotherClass)
            _myOtherClass = value
        End Set
    End Property

    Private _path As String
     _
    Public Property FolderPath() As String
        Get
            Return _path
        End Get
        Set(ByVal value As String)
            _path = value
        End Set
    End Property
End Class

 _
Public Class AnotherClass
    Private _name As String
    Private _editor As String
    Private _anotherPath As String

    Public Property Name() As String
        Get
            Return _name
        End Get
        Set(ByVal value As String)
            _name = value
        End Set
    End Property

     _
    Public Property AnotherFolderPath() As String
        Get
            Return _anotherPath
        End Get
        Set(ByVal value As String)
            _anotherPath = value
        End Set
    End Property

     _
    Public Property MyEditor() As String
        Get
            Return _editor
        End Get
        Set(ByVal value As String)
            _editor = value
        End Set
    End Property
End Class

Public Class MyCustomEditor
    Inherits System.Drawing.Design.UITypeEditor

    Public Overrides Function GetEditStyle(ByVal context As System.ComponentModel.ITypeDescriptorContext) As System.Drawing.Design.UITypeEditorEditStyle
        Return Drawing.Design.UITypeEditorEditStyle.Modal
    End Function

    Public Overrides Function EditValue(ByVal context As System.ComponentModel.ITypeDescriptorContext, ByVal provider As System.IServiceProvider, ByVal value As Object) As Object
        Dim editor As New Form
        editor.StartPosition = FormStartPosition.CenterParent
        editor.Text = "This is my editor"
        editor.Show()
        Return "Editor activated"
    End Function
End Class