Question

I have a user control with a property of type List<Something>:

Private p_myList As New List(Of Guid)
Public Property MyList() As List(Of Guid)
    Get
        Return p_myList
    End Get
    Set(ByVal value As List(Of Guid))
        If value Is Nothing Then Throw New ArgumentNullException()
        p_myList = value
    End Set
End Property

Is it popssible to set this property in the aspx source of the page using the UserControl, e.g., something like:

<uc1:myUserControl runat="server" MyList="3c7d794e-7645-46e7-bdde-a0bc42679261, 3c7d794e-7645-46e7-bdde-a0bc42679262" />

or do I need to create a “compatibility property” of type string which is then parsed? (I know that I could set these values through codebehind, but I’d prefer to do it in the aspx source.)

Answer 1

You need to create a TypeConvertor

Something like

public class GuidListTypeConverter : System.ComponentModel.TypeConverter 
{ 
    public override bool CanConvertFrom(System.ComponentModel.ITypeDescriptorContext context, Type sourceType) 
    { 
        return sourceType == typeof(Guid); 
    } 
    public override object ConvertFrom(System.ComponentModel.ITypeDescriptorContext context, System.Globalization.CultureInfo culture, object value) 
    { 
        string val = value as string; 

        string[] vals = val.Split(','); 
        System.Collections.Generic.List<Guid> ret = new System.Collections.Generic.List<Guid>();
        foreach (string s in vals)
        {
            ret.Add(Guid.Parse(s));
        }
        return ret;
    } 
}

Then

[TypeConverter(typeof(GuidListTypeConverter))]
public List<Guid> MyList {get;set;}