How to Create typeconverter dynamically by reflection to use in a PropertyGrid?

[Mohamed Ali Jinnah]

Hi, I am using the propertygrid control to get the application level parameters from the users. The object assigned to the propertygrid is created dynamically with help of reflection.emit. i achieved the functionalities of the propertygrid like Categories and Description of a property by using the SetCustomAttribute method of a property builder. I want to achieve the combo box functionality for a property (User can select a value from the combobox for the property). I know that we can achieve this by setting the TypeConverterAttribute for the property. My problem is, each property will have to show different values in the combo(Values are coming from a Database), so dynamically i have to create a TypeConverter which is inherited from StringConverter. This typeconverter should be assingned to the property by TypeConverterAttribute. My problem is how we have to create a TypeConverter which is inherited from StringConverter with help of Reflection.Emit. Please give you suggestions. Please find the code below. It is not working. I confused to write the reflection related codes. Please help me on this. Public Shared Function GetDynamicTypeConverted(ByRef foModuleBuilder As ModuleBuilder) As Type Dim oTypeBuilder As TypeBuilder = Nothing Dim oMethodBuilder As MethodBuilder = Nothing Dim oILGenerator As ILGenerator = Nothing Dim oConstructorInfo As ConstructorInfo = Nothing Dim oParams() As Type Try oTypeBuilder = foModuleBuilder.DefineType("EngStatusConverter", TypeAttributes.Class, GetType(StringConverter)) oMethodBuilder = oTypeBuilder.DefineMethod("GetStandardValuesSupported", MethodAttributes.Public, GetType(Boolean), New Type() {GetType(ITypeDescriptorContext)}) oILGenerator = oMethodBuilder.GetILGenerator oILGenerator.Emit(OpCodes.Ldarg_0, CType(True, Object)) oILGenerator.Emit(OpCodes.Ret) oMethodBuilder = oTypeBuilder.DefineMethod("GetStandardValues", MethodAttributes.Public, GetType(StandardValuesCollection), New Type() {GetType(ITypeDescriptorContext)}) oILGenerator = oMethodBuilder.GetILGenerator oParams = New Type() {GetType(String)} oConstructorInfo = GetType(StandardValuesCollection).GetConstructor(oParams) oILGenerator.Emit(OpCodes.Ldarg_0, oConstructorInfo) oILGenerator.Emit(OpCodes.Ret) oMet

[J4amieC]

Im not sure i totally understand your problem, but TypeConverter's are created by a call to TypeDescriptor.GetConverter[^]

[Mohamed Ali Jinnah]

Hi, Thanks for your reply. I have to attach a TypeConverterAttribute to a property. Please see the following code. Property definition ------------------------------------ _ Public Property DefaultFileName() As String Get Return _defaultFileName End Get Set(ByVal Value As String) _defaultFileName = Value End Set End Property ------------------------------------ File Name Converter ------------------------------------ Public Class FileNameConverter Inherits StringConverter Public Overloads Overrides Function GetStandardValuesSupported( _ ByVal context As ITypeDescriptorContext) As Boolean Return True End Function Public Overloads Overrides Function GetStandardValues( _ ByVal context As ITypeDescriptorContext) _ As StandardValuesCollection Return New StandardValuesCollection(New String() {"New File", _ "File1", _ "Document1"}) End Function Public Overloads Overrides Function GetStandardValuesExclusive( _ ByVal context As ITypeDescriptorContext) As Boolean Return False End Function End Class My problem is, I have to create the FileNameConverter type dynamically with help of reflection. So I can return the dynamic values from GetStandardValues method. I need a way to create a type like filenameconverter thru reflection. Please give your suggesstion.

[Danilo Corallo]

Hi, the answer to your need, is use an Attribute to pass the dynamic list to your TypeConverter. Please check my recent article here: http://www.codeproject.com/useritems/PropertyGridEx.asp Here is my TypeConverter ;) :

Public Class CustomChoices
Inherits ArrayList

Public Sub New(ByVal array As ArrayList, Optional ByVal IsSorted As Boolean = False)
    Me.AddRange(array)
    If IsSorted Then Me.Sort()
End Sub

Public Sub New(ByVal array() As String, Optional ByVal IsSorted As Boolean = False)
    Me.AddRange(array)
    If IsSorted Then Me.Sort()
End Sub

Public Sub New(ByVal array() As Integer, Optional ByVal IsSorted As Boolean = False)
    Me.AddRange(array)
    If IsSorted Then Me.Sort()
End Sub

Public Sub New(ByVal array() As Double, Optional ByVal IsSorted As Boolean = False)
    Me.AddRange(array)
    If IsSorted Then Me.Sort()
End Sub

Public Sub New(ByVal array() As Object, Optional ByVal IsSorted As Boolean = False)
    Me.AddRange(array)
    If IsSorted Then Me.Sort()
End Sub

Public ReadOnly Property Items() As ArrayList
    Get
        Return Me
    End Get
End Property

Public Class CustomChoicesTypeConverter
    Inherits TypeConverter
    Private oChoices As CustomChoicesAttributeList = Nothing
    Public Overrides Function GetStandardValuesSupported(ByVal context As System.ComponentModel.ITypeDescriptorContext) As Boolean
        Dim Choices As CustomChoicesAttributeList = context.PropertyDescriptor.Attributes(GetType(CustomChoicesAttributeList))

        If Not Choices Is Nothing Then
            oChoices = Choices
            GetStandardValuesSupported = True
        Else
            GetStandardValuesSupported = False
        End If
    End Function
    Public Overrides Function GetStandardValuesExclusive(ByVal context As System.ComponentModel.ITypeDescriptorContext) As Boolean
        Dim Choices As CustomChoicesAttributeList = context.PropertyDescriptor.Attributes(GetType(CustomChoicesAttributeList))

        If Not Choices Is Nothing Then
            oChoices = Choices
            GetStandardValuesExclusive = True
        Else
            GetStandardValuesExclusive = False
        End If
    End Function
    Public Overrides Function GetStandardValues(ByVal context As System.ComponentModel.ITypeDescriptorContext) As System.