Using a Dictionary in a propertygrid

Question

I'd like to edit a list of key value(string, string) items using a propertygrid. When I use a Dictionary<string,string> as type the propertygrid will show a GUI, but it does not seem "enabled", ie. I can't add any items.

Is the Dictionary object supported, or is there any other object with which I could solve this problem?

Answer 1

I have done it following this code in the past:

class DictionaryPropertyGridAdapter : ICustomTypeDescriptor
{
    IDictionary _dictionary;

    public DictionaryPropertyGridAdapter(IDictionary d)
    {
        _dictionary = d;
    }

    public string GetComponentName()
    {
        return TypeDescriptor.GetComponentName(this, true);
    }

    public EventDescriptor GetDefaultEvent()
    {
        return TypeDescriptor.GetDefaultEvent(this, true);
    }

    public string GetClassName()
    {
        return TypeDescriptor.GetClassName(this, true);
    }

    public EventDescriptorCollection GetEvents(Attribute[] attributes)
    {
        return TypeDescriptor.GetEvents(this, attributes, true);
    }

    EventDescriptorCollection System.ComponentModel.ICustomTypeDescriptor.GetEvents()
    {
        return TypeDescriptor.GetEvents(this, true);
    }

    public TypeConverter GetConverter()
    {
        return TypeDescriptor.GetConverter(this, true);
    }

    public object GetPropertyOwner(PropertyDescriptor pd)
    {
        return _dictionary;
    }

    public AttributeCollection GetAttributes()
    {
        return TypeDescriptor.GetAttributes(this, true);
    }

    public object GetEditor(Type editorBaseType)
    {
        return TypeDescriptor.GetEditor(this, editorBaseType, true);
    }

    public PropertyDescriptor GetDefaultProperty()
    {
        return null;
    }

    PropertyDescriptorCollection
        System.ComponentModel.ICustomTypeDescriptor.GetProperties()
    {
        return ((ICustomTypeDescriptor)this).GetProperties(new Attribute[0]);
    }

    public PropertyDescriptorCollection GetProperties(Attribute[] attributes)
    {
        ArrayList properties = new ArrayList();
        foreach (DictionaryEntry e in _dictionary)
        {
            properties.Add(new DictionaryPropertyDescriptor(_dictionary, e.Key));
        }

        PropertyDescriptor[] props =
            (PropertyDescriptor[])properties.ToArray(typeof(PropertyDescriptor));

        return new PropertyDescriptorCollection(props);
    }
}

class DictionaryPropertyDescriptor : PropertyDescriptor
{
    IDictionary _dictionary;
    object _key;

    internal DictionaryPropertyDescriptor(IDictionary d, object key)
        : base(key.ToString(), null)
    {
        _dictionary = d;
        _key = key;
    }

    public override Type PropertyType
    {
        get { return _dictionary[_key].GetType(); }
    }

    public override void SetValue(object component, object value)
    {
        _dictionary[_key] = value;
    }

    public override object GetValue(object component)
    {
        return _dictionary[_key];
    }

    public override bool IsReadOnly
    {
        get { return false; }
    }

    public override Type ComponentType
    {
        get { return null; }
    }

    public override bool CanResetValue(object component)
    {
        return false;
    }

    public override void ResetValue(object component)
    {
    }

    public override bool ShouldSerializeValue(object component)
    {
        return false;
    }
}

private void Form1_Load(object sender, System.EventArgs e)
{
    IDictionary d = new Hashtable();
    d["Hello"] = "World";
    d["Meaning"] = 42;
    d["Shade"] = Color.ForestGreen;

    propertyGrid1.SelectedObject = new DictionaryPropertyGridAdapter(d);
}

Worked well for us.

Answer 2

If you are trying to bind a class that contains a Dictionary property to a PropertyGrid, rather than binding the Dictionary itself directly, then here is a free (LGPL licensed) component that does exactly that: http://gendictedit.codeplex.com/