From Russia with Love – Retrieving ViewModel Objects from a Model Assembly

using System;
using System.Collections.ObjectModel;
using System.Windows;
using System.Windows.Input;
using ModelLib;
using MvvmFoundation.Wpf;

namespace TransformingModelToVM
{
    public class CommunityViewModel : ObservableObject
    {
        #region Methods

        public CommunityViewModel()
        {
            _memberCommandsInternal = new ObservableCollection<CommandViewModel>();
            this.MemberCommands = new ReadOnlyObservableCollection<CommandViewModel>(_memberCommandsInternal);

            // Create the command that is used by each CommandViewModel in MemberCommands.
            _selectMemberCommand = new RelayCommand<Person>(this.SelectMember);

            // Create the data source and begin a call to fetch and transform Person objects.
            var dataSource = new PersonDataSource();
            dataSource.RetrieveAndTransformAsync(
                _memberCommandsInternal,         // output
                this.CreateCommandForPerson,     // transform
                () => this.IsLoadingData = false // onCompleted
                ); 

            this.IsLoadingData = true;
        }

        void SelectMember(Person person)
        {
            // In a real app this method would do something with the selected Person.
            string msg = String.Format("You selected '{0}'.", FormatName(person));
            MessageBox.Show(msg, "Congratulations!");
        }

        CommandViewModel CreateCommandForPerson(Person person)
        {
            return new CommandViewModel(_selectMemberCommand, FormatName(person), person);
        }

        static string FormatName(Person person)
        {
            return String.Format("{0}, {1}", person.LastName, person.FirstName);
        }

        #endregion // Methods

        #region Properties

        /// <summary>
        /// Returns true if the community member data is
        /// currently being loaded from a data source.
        /// </summary>
        public bool IsLoadingData
        {
            get { return _isLoadingData; }
            private set
            {
                if (value.Equals(_isLoadingData))
                    return;

                _isLoadingData = value;

                base.RaisePropertyChanged("IsLoadingData");
            }
        }

        /// <summary>
        /// Returns a read-only collection of command objects, each of which represents a 
        /// member of the community.  When a command executes, it 'selects' the associated member.
        /// </summary>
        public ReadOnlyObservableCollection<CommandViewModel> MemberCommands { get; private set; }

        #endregion // Properties

        #region Fields

        bool _isLoadingData;
        readonly ObservableCollection<CommandViewModel> _memberCommandsInternal;
        readonly ICommand _selectMemberCommand;

        #endregion // Fields
    }
}