WPF MVVM communication entre le Modèle de Vue

J'ai créé ce Messenger classe permettant de gérer la communication entre les ViewModels.

Inscrire pour un objet personne dans MainViewModel:

Messenger.Default.Register<Person>(this, AddPersonToCollection, Context.Added);

De notifier à tous les inscrits Viewmodel sur la personne ajoutée à partir de la CreatePersonViewModel:

Messenger.Default.Send(person, Context.Added);

Code Source:

using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Linq;
namespace Application.Messaging
{
public class Messenger
{
private static readonly object CreationLock = new object();
private static readonly ConcurrentDictionary<MessengerKey, object> Dictionary = new ConcurrentDictionary<MessengerKey, object>();
#region Default property
private static Messenger _instance;
///<summary>
///Gets the single instance of the Messenger.
///</summary>
public static Messenger Default
{
get
{
if (_instance == null)
{
lock (CreationLock)
{
if (_instance == null)
{
_instance = new Messenger();
}
}
}
return _instance;
}
}
#endregion
///<summary>
///Initializes a new instance of the Messenger class.
///</summary>
private Messenger()
{
}
///<summary>
///Registers a recipient for a type of message T. The action parameter will be executed
///when a corresponding message is sent.
///</summary>
///<typeparam name="T"></typeparam>
///<param name="recipient"></param>
///<param name="action"></param>
public void Register<T>(object recipient, Action<T> action)
{
Register(recipient, action, null);
}
///<summary>
///Registers a recipient for a type of message T and a matching context. The action parameter will be executed
///when a corresponding message is sent.
///</summary>
///<typeparam name="T"></typeparam>
///<param name="recipient"></param>
///<param name="action"></param>
///<param name="context"></param>
public void Register<T>(object recipient, Action<T> action, object context)
{
var key = new MessengerKey(recipient, context);
Dictionary.TryAdd(key, action);
}
///<summary>
///Unregisters a messenger recipient completely. After this method is executed, the recipient will
///no longer receive any messages.
///</summary>
///<param name="recipient"></param>
public void Unregister(object recipient)
{
Unregister(recipient, null);
}
///<summary>
///Unregisters a messenger recipient with a matching context completely. After this method is executed, the recipient will
///no longer receive any messages.
///</summary>
///<param name="recipient"></param>
///<param name="context"></param>
public void Unregister(object recipient, object context)
{
object action;
var key = new MessengerKey(recipient, context);
Dictionary.TryRemove(key, out action);
}
///<summary>
///Sends a message to registered recipients. The message will reach all recipients that are
///registered for this message type.
///</summary>
///<typeparam name="T"></typeparam>
///<param name="message"></param>
public void Send<T>(T message)
{
Send(message, null);
}
///<summary>
///Sends a message to registered recipients. The message will reach all recipients that are
///registered for this message type and matching context.
///</summary>
///<typeparam name="T"></typeparam>
///<param name="message"></param>
///<param name="context"></param>
public void Send<T>(T message, object context)
{
IEnumerable<KeyValuePair<MessengerKey, object>> result;
if (context == null)
{
//Get all recipients where the context is null.
result = from r in Dictionary where r.Key.Context == null select r;
}
else
{
//Get all recipients where the context is matching.
result = from r in Dictionary where r.Key.Context != null && r.Key.Context.Equals(context) select r;
}
foreach (var action in result.Select(x => x.Value).OfType<Action<T>>())
{
//Send the message to all recipients.
action(message);
}
}
protected class MessengerKey
{
public object Recipient { get; private set; }
public object Context { get; private set; }
///<summary>
///Initializes a new instance of the MessengerKey class.
///</summary>
///<param name="recipient"></param>
///<param name="context"></param>
public MessengerKey(object recipient, object context)
{
Recipient = recipient;
Context = context;
}
///<summary>
///Determines whether the specified MessengerKey is equal to the current MessengerKey.
///</summary>
///<param name="other"></param>
///<returns></returns>
protected bool Equals(MessengerKey other)
{
return Equals(Recipient, other.Recipient) && Equals(Context, other.Context);
}
///<summary>
///Determines whether the specified MessengerKey is equal to the current MessengerKey.
///</summary>
///<param name="obj"></param>
///<returns></returns>
public override bool Equals(object obj)
{
if (ReferenceEquals(null, obj)) return false;
if (ReferenceEquals(this, obj)) return true;
if (obj.GetType() != GetType()) return false;
return Equals((MessengerKey)obj);
}
///<summary>
///Serves as a hash function for a particular type. 
///</summary>
///<returns></returns>
public override int GetHashCode()
{
unchecked
{
return ((Recipient != null ? Recipient.GetHashCode() : 0) * 397) ^ (Context != null ? Context.GetHashCode() : 0);
}
}
}
}
}

OriginalL'auteur Dalstroem