Provides a unified way of converting picked relation nodes as a specified type.

RelationConverter.cs

using System;
using System.ComponentModel;
using System.Globalization;
using System.Linq;
using nuPickers;
using Our.Umbraco.Ditto;

namespace MyProject.TypeConverters
{
    /// <summary>
    /// Provides a unified way of converting picked relation nodes as a specified type.
    /// </summary>
    /// <typeparam name="T">The <see cref="Type" /> of the object to return.</typeparam>
    public class RelationConverter<T> : TypeConverter where T : class
    {
        /// <summary>
        /// Returns whether this converter can convert an object of the given type to the type of this converter, using the specified context.
        /// </summary>
        /// <param name="context">An <see cref="T:System.ComponentModel.ITypeDescriptorContext" /> that provides a format context.</param>
        /// <param name="type">The type.</param>
        /// <returns>
        /// true if this converter can perform the conversion; otherwise, false.
        /// </returns>
        public override bool CanConvertFrom(ITypeDescriptorContext context, Type type)
        {
            return type == typeof(Picker);
        }

        /// <summary>
        /// Converts the given object to the type of this converter, using the specified context and culture information.
        /// </summary>
        /// <param name="context">An <see cref="T:System.ComponentModel.ITypeDescriptorContext" /> that provides a format context.</param>
        /// <param name="culture">The <see cref="T:System.Globalization.CultureInfo" /> to use as the current culture.</param>
        /// <param name="value">The <see cref="T:System.Object" /> to convert.</param>
        /// <returns>
        /// An <see cref="T:System.Object" /> that represents the converted value.
        /// </returns>
        public override object ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, object value)
        {
            if (value == null) return null;

            var picker = (Picker)value;
            var nodes = picker.AsPublishedContent().ToList();
            if (!nodes.Any()) return null;
            var objects = nodes.Select(x => x.As<T>()).ToList();
            return objects;
        }
    }
}