properties - PropertyGrid Browsable not found for entity framework created property, how to find it?

Question

Trying to remove or place items on a property grid by changing the Browsable attribute.

But unless browsable is set on object creation my code to change Browsable doesn't work. Now I can manually add browsable, but when I make a change to my entity (still developing project so lots of changes to entity) any additional attributes I add go away.

I attempted to set [Browsable(true)] two ways other ways: http://ardalis.com/adding-attributes-to-generated-classes and http://social.msdn.microsoft.com/Forums/en-US/adodotnetentityframework/thread/617ebfca-0f68-4b90-83fd-0da758fadbd0/

Both seem to actually set the Browsable correctly, but when I loop thru the Attributes in Property Descriptor it is not there (for me to change).

  String fieldname = "browsable"; // I also edit "description"
  PropertyDescriptor pd = TypeDescriptor.GetProperties(o.GetType())[propertyName];
  object attrib = null;
  AttributeCollection attribs = pd.Attributes;

  foreach (Attribute a in attribs)
    {
    if (a.GetType() == attributeType)
      {
      attrib = a;
      break;
      }
    }
// The microsoft documentation leads one to believe the following line of code would find the desired attribute,
// negating the need for the more complete foreach statement above.
// However,  it appears to find attribute even when it does not exist. Setting value for "found" attribute 
// will result in random memory being changed, which results in very unpredictable behavior.
// attrib = pd.Attributes[t];

if (attrib != null)
  {
  // locate field that contains value 
  FieldInfo field = attrib.GetType().GetField(fieldName, BindingFlags.NonPublic | BindingFlags.Instance);
  if (field != null)
    {
    if (field.FieldType == value.GetType())
      {
      // set field to desired value
      field.SetValue(attrib, value);
      }
    }
    }
  else
    {
    throw new Exception("Attribute (" + attributeType.Name + ") does not exist for Property(" + propertyName + ")");
    }

So I keep getting the Exception that I throw if it doesn't find "browsable" - but only if not set in Model.Designer.cs first.

Below is what my Model.Designer.cs looks like.

  /// <summary>
  /// No Metadata Documentation available.
  /// </summary>
  [EdmScalarPropertyAttribute(EntityKeyProperty=false, IsNullable=true)]
  [DataMemberAttribute()]
  [Browsable(false)] // this works, but goes away if change my entity
  public Nullable<global::System.TimeSpan> SignoutAfter
    {
    get
      {
      return _SignoutAfter;
      }
    set
      {
      OnSignoutAfterChanging(value);
      ReportPropertyChanging("SignoutAfter");
      _SignoutAfter = StructuralObject.SetValidValue(value);
      ReportPropertyChanged("SignoutAfter");
      OnSignoutAfterChanged();
      }
    }
  private Nullable<global::System.TimeSpan> _SignoutAfter;
  partial void OnSignoutAfterChanging(Nullable<global::System.TimeSpan> value);
  partial void OnSignoutAfterChanged();

So I need a way to either 1. add browsable to entity when I edit them so it is always on perhaps editing the t4, but I don't even know where to begin with that or 2. Another way to add or remove (and edit) the properties (see I might edit the description based on some logic) or 3 find the hole in my code so I can find and edit browsable (description and displayname).

Update The second link above, http://social.msdn.microsoft.com/Forums/en-US/adodotnetentityframework/thread/617ebfca-0f68-4b90-83fd-0da758fadbd0/ , has a lot of what I need, I think. Adding a Attribute array variable to the class and some code to see if that is set seems to have the effect that I am looking for. But leaving this open to find a better answer.

partial class Client : ICustomTypeDescriptor
  {
   public Attribute[] SignOutAttributes; // added this

   #region ICustomTypeDescriptor Members

   ... // see the link for the other code

   public PropertyDescriptorCollection GetProperties (Attribute[] attributes)
      {
      var propsColl = TypeDescriptor.GetProperties (this, attributes, true);
      var props = new List<PropertyDescriptor> ();
      foreach (PropertyDescriptor prop in propsColl)
         {
         String strUPPERCaseName = prop.Name.ToUpper (); // for my thick fingers
         // make sure case values are upper case 
         switch (strUPPERCaseName)
            {
            case "SIGNOUTAFTER":
               if (SignOutAttributes != null)
                  {
                  props.Add(new CustomPropertyDescriptor(prop, SignOutAttributes));
                  }
                else
                  {
                   props.Add (new CustomPropertyDescriptor (prop, new Attribute[]
                     {
                     new CategoryAttribute("Settings"),
                     new DisplayNameAttribute("Signout After"),
                     new BrowsableAttribute(true),
                     new ReadOnlyAttribute(false)
                     }));
                  }
                break;
            default:
               props.Add (prop);
               break;
            }
         }
       return new PropertyDescriptorCollection (props.ToArray ());
       }

In my code I can change the Attribute Array to have what Attribute values I want.

 _client.SignOutAttributes = new Attribute[]
                {
                    new CategoryAttribute ("My Category"),
                    new DisplayNameAttribute("Signout After"),
                    new BrowsableAttribute(true),
                    new ReadOnlyAttribute(false)
                };

I'm not 100% happy with this. I have to write code for each Property.

Answer 1

Using ICustomTypeDescriptor is definitely the good solution when you want dynamic (set at runtime) properties. Here is generic ICustomTypeDescriptor utility class that I've been using for this sort of property grid hacking, it's pretty straightforward to use:

public sealed class DynamicTypeDescriptor: ICustomTypeDescriptor, INotifyPropertyChanged
{
    private Type _type;
    private AttributeCollection _attributes;
    private TypeConverter _typeConverter;
    private Dictionary<Type, object> _editors;
    private EventDescriptor _defaultEvent;
    private PropertyDescriptor _defaultProperty;
    private EventDescriptorCollection _events;

    public event PropertyChangedEventHandler PropertyChanged;

    private DynamicTypeDescriptor()
    {
    }

    public DynamicTypeDescriptor(Type type)
    {
        if (type == null)
            throw new ArgumentNullException("type");

        _type = type;
        _typeConverter = TypeDescriptor.GetConverter(type);
        _defaultEvent = TypeDescriptor.GetDefaultEvent(type);
        _defaultProperty = TypeDescriptor.GetDefaultProperty(type);
        _events = TypeDescriptor.GetEvents(type);

        List<PropertyDescriptor> normalProperties = new List<PropertyDescriptor>();
        OriginalProperties = TypeDescriptor.GetProperties(type);
        foreach (PropertyDescriptor property in OriginalProperties)
        {
            if (!property.IsBrowsable)
                continue;

            normalProperties.Add(property);

        }
        Properties = new PropertyDescriptorCollection(normalProperties.ToArray());

        _attributes = TypeDescriptor.GetAttributes(type);

        _editors = new Dictionary<Type, object>();
        object editor = TypeDescriptor.GetEditor(type, typeof(UITypeEditor));
        if (editor != null)
        {
            _editors.Add(typeof(UITypeEditor), editor);
        }
        editor = TypeDescriptor.GetEditor(type, typeof(ComponentEditor));
        if (editor != null)
        {
            _editors.Add(typeof(ComponentEditor), editor);
        }
        editor = TypeDescriptor.GetEditor(type, typeof(InstanceCreationEditor));
        if (editor != null)
        {
            _editors.Add(typeof(InstanceCreationEditor), editor);
        }
    }

    public T GetPropertyValue<T>(string name, T defaultValue)
    {
        if (name == null)
            throw new ArgumentNullException("name");

        foreach (PropertyDescriptor pd in Properties)
        {
            if (pd.Name == name)
            {
                try
                {
                    return (T)Convert.ChangeType(pd.GetValue(Component), typeof(T));
                }
                catch
                {
                    return defaultValue;
                }
            }
        }
        return defaultValue;
    }

    public void SetPropertyValue(string name, object value)
    {
        if (name == null)
            throw new ArgumentNullException("name");

        foreach (PropertyDescriptor pd in Properties)
        {
            if (pd.Name == name)
            {
                pd.SetValue(Component, value);
                break;
            }
        }
    }

    internal void OnValueChanged(PropertyDescriptor prop)
    {
        PropertyChangedEventHandler handler = PropertyChanged;
        if (handler != null)
        {
            handler(this, new PropertyChangedEventArgs(prop.Name));
        }
    }

    internal static T GetAttribute<T>(AttributeCollection attributes) where T : Attribute
    {
        if (attributes == null)
            return null;

        foreach (Attribute att in attributes)
        {
            if (typeof(T).IsAssignableFrom(att.GetType()))
                return (T)att;
        }
        return null;
    }

    public sealed class DynamicProperty: PropertyDescriptor, INotifyPropertyChanged
    {
        private readonly Type _type;
        private readonly bool _hasDefaultValue;
        private readonly object _defaultValue;
        private readonly PropertyDescriptor _existing;
        private readonly DynamicTypeDescriptor _descriptor;
        private Dictionary<Type, object> _editors;
        private bool? _readOnly;
        private bool? _browsable;
        private string _displayName;
        private string _description;
        private string _category;
        private List<Attribute> _attributes = new List<Attribute>();

        public event PropertyChangedEventHandler PropertyChanged;

        internal DynamicProperty(DynamicTypeDescriptor descriptor, Type type, object value, string name, Attribute[] attrs)
            : base(name, attrs)
        {
            _descriptor = descriptor;
            _type = type;
            Value = value;
            DefaultValueAttribute def = DynamicTypeDescriptor.GetAttribute<DefaultValueAttribute>(Attributes);
            if (def == null)
            {
                _hasDefaultValue = false;
            }
            else
            {
                _hasDefaultValue = true;
                _defaultValue = def.Value;
            }
            if (attrs != null)
            {
                foreach (Attribute att in attrs)
                {
                    _attributes.Add(att);
                }
            }
        }

        internal static Attribute[] GetAttributes(PropertyDescriptor existing)
        {
            List<Attribute> atts = new List<Attribute>();
            foreach (Attribute a in existing.Attributes)
            {
                atts.Add(a);
            }
            return atts.ToArray();
        }

        internal DynamicProperty(DynamicTypeDescriptor descriptor, PropertyDescriptor existing, object component)
            : this(descriptor, existing.PropertyType, existing.GetValue(component), existing.Name, GetAttributes(existing))
        {
            _existing = existing;
        }

        public void RemoveAttributesOfType<T>() where T : Attribute
        {
            List<Attribute> remove = new List<Attribute>();
            foreach (Attribute att in _attributes)
            {
                if (typeof(T).IsAssignableFrom(att.GetType()))
                {
                    remove.Add(att);
                }
            }

            foreach (Attribute att in remove)
            {
                _attributes.Remove(att);
            }
        }

        public IList<Attribute> AttributesList
        {
            get
            {
                return _attributes;
            }
        }

        public override AttributeCollection Attributes
        {
            get
            {
                return new AttributeCollection(_attributes.ToArray());
            }
        }

        public object Value { get; set; }

        public override bool CanResetValue(object component)
        {
            if (_existing != null)
                return _existing.CanResetValue(component);

            return _hasDefaultValue;
        }

        public override Type ComponentType
        {
            get
            {
                if (_existing != null)
                    return _existing.ComponentType;

                return typeof(object);
            }
        }

        public override object GetValue(object component)
        {
            if (_existing != null)
                return _existing.GetValue(component);

            return Value;
        }

        public override string Category
        {
            get
            {
                if (_category != null)
                    return _category;

                return base.Category;
            }
        }

        public void SetCategory(string category)
        {
            _category = category;
        }

        public override string Description
        {
            get
            {
                if (_description != null)
                    return _description;

                return base.Description;
            }
        }

        public void SetDescription(string description)
        {
            _description = description;
        }

        public override string DisplayName
        {
            get
            {
                if (_displayName != null)
                    return _displayName;

                if (_existing != null)
                    return _existing.DisplayName;

                return base.DisplayName;
            }
        }

        public void SetDisplayName(string displayName)
        {
            _displayName = displayName;
        }

        public override bool IsBrowsable
        {
            get
            {
                if (_browsable.HasValue)
                    return _browsable.Value;

                return base.IsBrowsable;
            }
        }

        public void SetBrowsable(bool browsable)
        {
            _browsable = browsable;
        }

        public override bool IsReadOnly
        {
            get
            {
                if (_readOnly.HasValue)
                    return _readOnly.Value;

                if (_existing != null)
                    return _existing.IsReadOnly;

                ReadOnlyAttribute att = DynamicTypeDescriptor.GetAttribute<ReadOnlyAttribute>(Attributes);
                if (att == null)
                    return false;

                return att.IsReadOnly;
            }
        }

        public void SetIsReadOnly(bool readOnly)
        {
            _readOnly = readOnly;
        }

        public override Type PropertyType
        {
            get
            {
                if (_existing != null)
                    return _existing.PropertyType;

                return _type;
            }
        }

        public override void ResetValue(object component)
        {
            if (_existing != null)
            {
                _existing.ResetValue(component);
                PropertyChangedEventHandler handler = PropertyChanged;
                if (handler != null)
                {
                    handler(this, new PropertyChangedEventArgs(Name));
                }
                _descriptor.OnValueChanged(this);
                return;
            }

            if (CanResetValue(component))
            {
                Value = _defaultValue;
                _descriptor.OnValueChanged(this);
            }
        }

        public override void SetValue(object component, object value)
        {
            if (_existing != null)
            {
                _existing.SetValue(component, value);
                PropertyChangedEventHandler handler = PropertyChanged;
                if (handler != null)
                {
                    handler(this, new PropertyChangedEventArgs(Name));
                }
                _descriptor.OnValueChanged(this);
                return;
            }

            Value = value;
            _descriptor.OnValueChanged(this);
        }

        public override bool ShouldSerializeValue(object component)
        {
            if (_existing != null)
                return _existing.ShouldSerializeValue(component);

            return false;
        }

        public override object GetEditor(Type editorBaseType)
        {
            if (editorBaseType == null)
                throw new ArgumentNullException("editorBaseType");

            if (_editors != null)
            {
                object type;
                if ((_editors.TryG