How can I add my attributes to Code-Generated Linq2Sql classes properties?

Question

I would like to add attributes to Linq 2 Sql classes properties. Such as this Column is browsable in the UI or ReadOnly in the UI and so far.

I\'ve thought about usi

Answer 1

As requested, here's an approach using a CustomTypeDescriptor to edit the attributes at run-time; the example here is win-forms, but it should be pretty simple to swap it into WPF to see if it works...

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Windows.Forms;
// example POCO
class Foo {
    static Foo()
    {   // initializes the custom provider (the attribute-based approach doesn't allow
        // access to the original provider)
        TypeDescriptionProvider basic = TypeDescriptor.GetProvider(typeof(Foo));
        FooTypeDescriptionProvider custom = new FooTypeDescriptionProvider(basic);
        TypeDescriptor.AddProvider(custom, typeof(Foo));
    }
    public string Name { get; set; }
    public DateTime DateOfBirth { get; set; }
}
// example form
static class Program {
    [STAThread]
    static void Main() {
        Application.EnableVisualStyles();
        Application.Run( new Form {
                Controls = {
                    new DataGridView {
                        Dock = DockStyle.Fill,
                        DataSource = new BindingList {
                            new Foo { Name = "Fred", DateOfBirth = DateTime.Today.AddYears(-20) }
                        }
                    }
                }
            });
    }
}

class FooTypeDescriptionProvider : TypeDescriptionProvider
{
    ICustomTypeDescriptor descriptor;
    public FooTypeDescriptionProvider(TypeDescriptionProvider parent) : base(parent) { }
    public override ICustomTypeDescriptor GetTypeDescriptor(Type objectType, object instance)
    {   // swap regular descriptor for bespoke (Foo) descriptor
        if (descriptor == null)
        {
            ICustomTypeDescriptor desc = base.GetTypeDescriptor(typeof(Foo), null);
            descriptor = new FooTypeDescriptor(desc);
        }
        return descriptor;
    }
}
class FooTypeDescriptor : CustomTypeDescriptor
{
    internal FooTypeDescriptor(ICustomTypeDescriptor parent) : base(parent) { }
    public override PropertyDescriptorCollection GetProperties()
    {   // wrap the properties
        return Wrap(base.GetProperties());
    }
    public override PropertyDescriptorCollection GetProperties(Attribute[] attributes)
    {   // wrap the properties
        return Wrap(base.GetProperties(attributes));
    }

    static PropertyDescriptorCollection Wrap(PropertyDescriptorCollection properties)
    {
        // here's where we have an opportunity to swap/add/remove properties
        // at runtime; we'll swap them for pass-thru properties with
        // edited atttibutes
        List list = new List(properties.Count);
        foreach (PropertyDescriptor prop in properties)
        {
            // add custom attributes here...
            string displayName = prop.DisplayName;
            if (string.IsNullOrEmpty(displayName)) displayName = prop.Name;

            list.Add(new ChainedPropertyDescriptor(prop, new DisplayNameAttribute("Foo:" + displayName)));
        }
        return new PropertyDescriptorCollection(list.ToArray(), true);
    }
}


class ChainedPropertyDescriptor : PropertyDescriptor
{
    // this passes all requests through to the underlying (parent)
    // descriptor, but has custom attributes etc;
    // we could also override properties here...
    private readonly PropertyDescriptor parent;
    public ChainedPropertyDescriptor(PropertyDescriptor parent, params Attribute[] attributes)
        : base(parent, attributes)
    {
        this.parent = parent;
    }
    public override bool ShouldSerializeValue(object component) { return parent.ShouldSerializeValue(component); }
    public override void SetValue(object component, object value) { parent.SetValue(component, value); }
    public override object GetValue(object component) { return parent.GetValue(component); }
    public override void ResetValue(object component) { parent.ResetValue(component); }
    public override Type PropertyType {get { return parent.PropertyType; } }
    public override bool IsReadOnly { get { return parent.IsReadOnly; } }
    public override bool CanResetValue(object component) {return parent.CanResetValue(component);}
    public override Type ComponentType { get { return parent.ComponentType; } }
    public override void AddValueChanged(object component, EventHandler handler) {parent.AddValueChanged(component, handler);  }
    public override void RemoveValueChanged(object component, EventHandler handler) { parent.RemoveValueChanged(component, handler); }
    public override bool SupportsChangeEvents { get { return parent.SupportsChangeEvents; } }
}