ASP.NET Tutorial/Custom Controls/TypeConverter

Applying the TypeConverter attribute to a property (C#)

using System;
using System.Collections.Generic;
using System.ruponentModel;
using System.Text;
using System.Web.UI;
using System.Web.UI.WebControls;
namespace WebControlLibrary1
{
    [DefaultProperty("Text")]
    [ToolboxData("<{0}:WebCustomControl1 runat=server></{0}:WebCustomControl1>")]
    public class WebCustomControl1 : WebControl
    {
        private string text;
        private Guid _bookid;
        [Bindable(true)]
        [Category("Appearance")]
        [DefaultValue("")]
        public string Text
        {
            get
            {
                return text;
            }
            set
            {
                text = value;
            }
        }
        [Bindable(true)]
        [Category("Appearance")]
        [DefaultValue("")]
        [TypeConverter(typeof(GuidConverter))]
        public Guid BookId
        {
            get
            {
                return _bookid;
            }
            set
            {
                _bookid = value;
            }
        }

        protected override void Render(HtmlTextWriter output)
        {
            output.RenderBeginTag(HtmlTextWriterTag.Input);
            output.RenderEndTag();
        }
    }
}

Applying the TypeConverter attribute to a property (VB)

Imports System.ruponentModel
Imports System.Web.UI
<DefaultProperty("Text"), _
 ToolboxData("<{0}:WebCustomControl1 runat=server></{0}:WebCustomControl1>")> _
Public Class WebCustomControl1
    Inherits System.Web.UI.WebControls.WebControl
    Dim _text As String
    Dim _bookid As Guid
    <Bindable(True), Category("Appearance"), DefaultValue("")> _
    Property [Text]() As String
        Get
            Return _text
        End Get
        Set(ByVal Value As String)
            _text = Value
        End Set
    End Property
    <Bindable(True)> _
    <Category("Appearance")> _
    <DefaultValue("")> _
    <TypeConverter(GetType(GuidConverter))> _
    Property BookId() As System.Guid
        Get
            Return _bookid
        End Get
        Set(ByVal Value As System.Guid)
            _bookid = Value
        End Set
    End Property

    Protected Overrides Sub Render(ByVal output As System.Web.UI.HtmlTextWriter)
        output.RenderBeginTag(HtmlTextWriterTag.Input)
        output.RenderEndTag()
    End Sub
End Class

Creating a custom type converter (C#)

using System;
using System.ruponentModel;
using System.Globalization;
public class Name
{
    private string _first;
    private string _last;
    public Name(string first, string last)
    {
        _first = first;
        _last = last;
    }
    public string First
    {
        get { return _first; }
        set { _first = value; }
    }
    public string Last
    {
        get { return _last; }
        set { _last = value; }
    }
}
public class NameConverter : TypeConverter
{
    public override bool CanConvertFrom(ITypeDescriptorContext context,
       Type sourceType)
    {
        if (sourceType == typeof(string))
        {
            return true;
        }
        return base.CanConvertFrom(context, sourceType);
    }
    public override object ConvertFrom(ITypeDescriptorContext context,
       CultureInfo culture, object value)
    {
        if (value is string)
        {
            string[] v = ((string)value).Split(new char[] { " " });
            return new Name(v[0], v[1]);
        }
        return base.ConvertFrom(context, culture, value);
    }
    public override object ConvertTo(ITypeDescriptorContext context,
       CultureInfo culture, object value, Type destinationType)
    {
        if (destinationType == typeof(string))
        {
            return ((Name)value).First + " " + ((Name)value).Last;
        }
        return base.ConvertTo(context, culture, value, destinationType);
    }
}

Creating a custom type converter (VB)

Imports System
Imports System.ruponentModel
Imports System.Globalization
Public Class Name
    Private _first As String
    Private _last As String
    Public Sub New(ByVal first As String, ByVal last As String)
        _first = first
        _last = last
    End Sub
    Public Property First() As String
        Get
            Return _first
        End Get
        Set(ByVal value As String)
            _first = value
        End Set
    End Property
    Public Property Last() As String
        Get
            Return _last
        End Get
        Set(ByVal value As String)
            _last = value
        End Set
    End Property
End Class
Public Class NameConverter
    Inherits TypeConverter
    Public Overrides Function CanConvertFrom(ByVal context As _
       ITypeDescriptorContext, ByVal sourceType As Type) As Boolean
        If (sourceType Is GetType(String)) Then
            Return True
        End If
        Return MyBase.CanConvertFrom(context, sourceType)
    End Function
    Public Overrides Function ConvertFrom( _
            ByVal context As ITypeDescriptorContext, _
            ByVal culture As CultureInfo, ByVal value As Object) As Object
        If (value Is GetType(String)) Then
            Dim v As String() = (CStr(value).Split(New [Char]() {" "c}))
            Return New Name(v(0), v(1))
        End If
        Return MyBase.ConvertFrom(context, culture, value)
    End Function
    Public Overrides Function ConvertTo( _
            ByVal context As ITypeDescriptorContext, _
            ByVal culture As CultureInfo, ByVal value As Object, _
            ByVal destinationType As Type) As Object
        If (destinationType Is GetType(String)) Then
            Return (CType(value, Name).First + " " + (CType(value, Name).Last))
        End If
        Return MyBase.ConvertTo(context, culture, value, destinationType)
    End Function
End Class