Я написал следующий класс, который реализует (или пытается!) словарь с уведомлениями:
public partial class ObservableDictionary<TKey, TValue> : Dictionary<TKey, TValue>, INotifyCollectionChanged
{
public ObservableDictionary() : base() { }
public ObservableDictionary(int capacity) : base(capacity) { }
public ObservableDictionary(IEqualityComparer<TKey> comparer) : base(comparer) { }
public ObservableDictionary(IDictionary<TKey, TValue> dictionary) : base(dictionary) { }
public ObservableDictionary(int capacity, IEqualityComparer<TKey> comparer) : base(capacity, comparer) { }
public ObservableDictionary(IDictionary<TKey, TValue> dictionary, IEqualityComparer<TKey> comparer) : base(dictionary, comparer) { }
public event NotifyCollectionChangedEventHandler CollectionChanged;
public new TValue this[TKey key]
{
get
{
return base[key];
}
set
{
OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Replace, key, 0));
base[key] = value;
}
}
public new void Add(TKey key, TValue value)
{
base.Add(key, value);
OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Add, key, 0));
}
public new bool Remove(TKey key)
{
bool x = base.Remove(key);
OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Remove, key, 0));
return x;
}
public new void Clear()
{
base.Clear();
OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
}
protected virtual void OnCollectionChanged(NotifyCollectionChangedEventArgs e)
{
if (CollectionChanged != null)
{
CollectionChanged(this, e);
}
}
}
В другом классе у меня есть слушатель для события MyObservableDictionary.CollectionChanged:
Проблема, с которой я сталкиваюсь, заключается в том, что событие не срабатывает. Как я могу это исправить?
Я предлагаю вам реализовать IDictionary<TKey, TValue> вместо наследования с Dictionary<TKey, TValue>. Поскольку вы должны использовать new, а не override, возможно, что методы просто вызываются в базовом классе, а не в вашем классе. У меня возникло бы желание использовать Dictionary<TKey, TValue> для внутреннего хранения данных.
Фактически я нашел это: http://blogs.microsoft.co.il/blogs/shimmy/archive/2010/12/26/observabledictionary-lt-tkey-tvalue-gt-c.aspx
Microsoft ParallelExtensionsExtras предоставляет этот класс, который не только можно наблюдать, но и одновременно:
Теперь доступно через Nuget: https://www.nuget.org/packages/MSFT.ParallelExtensionsExtras/
Обратите внимание, что некоторые функции теперь являются частью более новых платформ .NET. ParallelExtensions "Extras" все еще имеют значение?
Блог Microsoft Tour: https://blogs.msdn.microsoft.com/pfxteam/2010/04/04/a-tour-of-parallelextensionsextras/
Пример кода параллельного программирования (исходный код параллельных расширений): https://code.msdn.microsoft.com/ParExtSamples
//--------------------------------------------------------------------------
//
// Copyright (c) Microsoft Corporation. All rights reserved.
//
// File: ObservableConcurrentDictionary.cs
//
//--------------------------------------------------------------------------
using System.Collections.Generic;
using System.Collections.Specialized;
using System.ComponentModel;
using System.Threading;
using System.Diagnostics;
namespace System.Collections.Concurrent
{
/// <summary>
/// Provides a thread-safe dictionary for use with data binding.
/// </summary>
/// <typeparam name="TKey">Specifies the type of the keys in this collection.</typeparam>
/// <typeparam name="TValue">Specifies the type of the values in this collection.</typeparam>
[DebuggerDisplay("Count={Count}")]
public class ObservableConcurrentDictionary<TKey, TValue> :
ICollection<KeyValuePair<TKey, TValue>>, IDictionary<TKey, TValue>,
INotifyCollectionChanged, INotifyPropertyChanged
{
private readonly SynchronizationContext _context;
private readonly ConcurrentDictionary<TKey, TValue> _dictionary;
/// <summary>
/// Initializes an instance of the ObservableConcurrentDictionary class.
/// </summary>
public ObservableConcurrentDictionary()
{
_context = AsyncOperationManager.SynchronizationContext;
_dictionary = new ConcurrentDictionary<TKey, TValue>();
}
/// <summary>Event raised when the collection changes.</summary>
public event NotifyCollectionChangedEventHandler CollectionChanged;
/// <summary>Event raised when a property on the collection changes.</summary>
public event PropertyChangedEventHandler PropertyChanged;
/// <summary>
/// Notifies observers of CollectionChanged or PropertyChanged of an update to the dictionary.
/// </summary>
private void NotifyObserversOfChange()
{
var collectionHandler = CollectionChanged;
var propertyHandler = PropertyChanged;
if (collectionHandler != null || propertyHandler != null)
{
_context.Post(s =>
{
if (collectionHandler != null)
{
collectionHandler(this, new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
}
if (propertyHandler != null)
{
propertyHandler(this, new PropertyChangedEventArgs("Count"));
propertyHandler(this, new PropertyChangedEventArgs("Keys"));
propertyHandler(this, new PropertyChangedEventArgs("Values"));
}
}, null);
}
}
/// <summary>Attempts to add an item to the dictionary, notifying observers of any changes.</summary>
/// <param name="item">The item to be added.</param>
/// <returns>Whether the add was successful.</returns>
private bool TryAddWithNotification(KeyValuePair<TKey, TValue> item)
{
return TryAddWithNotification(item.Key, item.Value);
}
/// <summary>Attempts to add an item to the dictionary, notifying observers of any changes.</summary>
/// <param name="key">The key of the item to be added.</param>
/// <param name="value">The value of the item to be added.</param>
/// <returns>Whether the add was successful.</returns>
private bool TryAddWithNotification(TKey key, TValue value)
{
bool result = _dictionary.TryAdd(key, value);
if (result) NotifyObserversOfChange();
return result;
}
/// <summary>Attempts to remove an item from the dictionary, notifying observers of any changes.</summary>
/// <param name="key">The key of the item to be removed.</param>
/// <param name="value">The value of the item removed.</param>
/// <returns>Whether the removal was successful.</returns>
private bool TryRemoveWithNotification(TKey key, out TValue value)
{
bool result = _dictionary.TryRemove(key, out value);
if (result) NotifyObserversOfChange();
return result;
}
/// <summary>Attempts to add or update an item in the dictionary, notifying observers of any changes.</summary>
/// <param name="key">The key of the item to be updated.</param>
/// <param name="value">The new value to set for the item.</param>
/// <returns>Whether the update was successful.</returns>
private void UpdateWithNotification(TKey key, TValue value)
{
_dictionary[key] = value;
NotifyObserversOfChange();
}
#region ICollection<KeyValuePair<TKey,TValue>> Members
void ICollection<KeyValuePair<TKey, TValue>>.Add(KeyValuePair<TKey, TValue> item)
{
TryAddWithNotification(item);
}
void ICollection<KeyValuePair<TKey, TValue>>.Clear()
{
((ICollection<KeyValuePair<TKey, TValue>>)_dictionary).Clear();
NotifyObserversOfChange();
}
bool ICollection<KeyValuePair<TKey, TValue>>.Contains(KeyValuePair<TKey, TValue> item)
{
return ((ICollection<KeyValuePair<TKey, TValue>>)_dictionary).Contains(item);
}
void ICollection<KeyValuePair<TKey, TValue>>.CopyTo(KeyValuePair<TKey, TValue>[] array, int arrayIndex)
{
((ICollection<KeyValuePair<TKey, TValue>>)_dictionary).CopyTo(array, arrayIndex);
}
int ICollection<KeyValuePair<TKey, TValue>>.Count
{
get { return ((ICollection<KeyValuePair<TKey, TValue>>)_dictionary).Count; }
}
bool ICollection<KeyValuePair<TKey, TValue>>.IsReadOnly
{
get { return ((ICollection<KeyValuePair<TKey, TValue>>)_dictionary).IsReadOnly; }
}
bool ICollection<KeyValuePair<TKey, TValue>>.Remove(KeyValuePair<TKey, TValue> item)
{
TValue temp;
return TryRemoveWithNotification(item.Key, out temp);
}
#endregion
#region IEnumerable<KeyValuePair<TKey,TValue>> Members
IEnumerator<KeyValuePair<TKey, TValue>> IEnumerable<KeyValuePair<TKey, TValue>>.GetEnumerator()
{
return ((ICollection<KeyValuePair<TKey, TValue>>)_dictionary).GetEnumerator();
}
IEnumerator IEnumerable.GetEnumerator()
{
return ((ICollection<KeyValuePair<TKey, TValue>>)_dictionary).GetEnumerator();
}
#endregion
#region IDictionary<TKey,TValue> Members
public void Add(TKey key, TValue value)
{
TryAddWithNotification(key, value);
}
public bool ContainsKey(TKey key)
{
return _dictionary.ContainsKey(key);
}
public ICollection<TKey> Keys
{
get { return _dictionary.Keys; }
}
public bool Remove(TKey key)
{
TValue temp;
return TryRemoveWithNotification(key, out temp);
}
public bool TryGetValue(TKey key, out TValue value)
{
return _dictionary.TryGetValue(key, out value);
}
public ICollection<TValue> Values
{
get { return _dictionary.Values; }
}
public TValue this[TKey key]
{
get { return _dictionary[key]; }
set { UpdateWithNotification(key, value); }
}
#endregion
}
}
Ваше решение - Исправлено;)
public class ObservableDictionary<TKey, TValue> : Dictionary<TKey, TValue>, INotifyCollectionChanged, INotifyPropertyChanged {
public ObservableDictionary( ) : base( ) { }
public ObservableDictionary(int capacity) : base(capacity) { }
public ObservableDictionary(IEqualityComparer<TKey> comparer) : base(comparer) { }
public ObservableDictionary(IDictionary<TKey, TValue> dictionary) : base(dictionary) { }
public ObservableDictionary(int capacity, IEqualityComparer<TKey> comparer) : base(capacity, comparer) { }
public ObservableDictionary(IDictionary<TKey, TValue> dictionary, IEqualityComparer<TKey> comparer) : base(dictionary, comparer) { }
public event NotifyCollectionChangedEventHandler CollectionChanged;
public event PropertyChangedEventHandler PropertyChanged;
public new TValue this[TKey key] {
get {
return base[key];
}
set {
TValue oldValue;
bool exist = base.TryGetValue(key, out oldValue);
var oldItem = new KeyValuePair<TKey, TValue>(key, oldValue);
base[key] = value;
var newItem = new KeyValuePair<TKey, TValue>(key, value);
if (exist) {
this.OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Replace, newItem, oldItem, base.Keys.ToList( ).IndexOf(key)));
} else {
this.OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Add, newItem, base.Keys.ToList( ).IndexOf(key)));
this.OnPropertyChanged(new PropertyChangedEventArgs(nameof(Count)));
}
}
}
public new void Add(TKey key, TValue value) {
if (!base.ContainsKey(key)) {
var item = new KeyValuePair<TKey, TValue>(key, value);
base.Add(key, value);
this.OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Add, item, base.Keys.ToList( ).IndexOf(key)));
this.OnPropertyChanged(new PropertyChangedEventArgs(nameof(Count)));
}
}
public new bool Remove(TKey key) {
TValue value;
if (base.TryGetValue(key, out value)) {
var item = new KeyValuePair<TKey, TValue>(key, base[key]);
bool result = base.Remove(key);
this.OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Remove, item, base.Keys.ToList( ).IndexOf(key)));
this.OnPropertyChanged(new PropertyChangedEventArgs(nameof(Count)));
return result;
}
return false;
}
public new void Clear( ) {
base.Clear( );
this.OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
this.OnPropertyChanged(new PropertyChangedEventArgs(nameof(Count)));
}
protected virtual void OnCollectionChanged(NotifyCollectionChangedEventArgs e) {
if (this.CollectionChanged != null) {
this.CollectionChanged(this, e);
}
}
protected virtual void OnPropertyChanged(PropertyChangedEventArgs e) {
if (this.PropertyChanged != null) {
this.PropertyChanged(this, e);
}
}
}
Я выкатил свой собственный: https://www.nuget.org/packages/hellosam.net.collections/
Использует дерево AVL, поэтому операции O (log N) вместо этого, где большинство реализаций, которые я видел с помощью List.indexOf(), являются O (N).
Он может даже наблюдать за вашим элементом INotifyPropertyChanged и преобразовывать их в наблюдаемое событие коллекции, чтобы сохранить ответ сортировки/группы DataGrid на изменение.
Как указали в этом ответе Игнатио и Мэтью, только повышение уведомления об изменении коллекции Reset является некорректным и не очень полезным, если вызывающий должен знать, что на самом деле изменилось. К счастью, это легко исправить. Обратите внимание, что эта версия использует Send вместо Post как Натан упоминал в предыдущем ответе, потому что WPF чувствителен к тому, чтобы сообщать правильный индекс при удалении, и неправильное его получение приводит к этому запутанному исключению. (Будьте бдительны: я все еще не совсем убежден, что указанный индекс будет полностью надежным, если будет много перекрывающихся изменений, особенно учитывая, что словари должны рассматриваться как неупорядоченные.)
//--------------------------------------------------------------------------
//
// Copyright (c) Microsoft Corporation. All rights reserved.
//
// File: ObservableConcurrentDictionary.cs
//
//--------------------------------------------------------------------------
using System.Collections.Generic;
using System.Collections.Specialized;
using System.ComponentModel;
using System.Threading;
using System.Diagnostics;
namespace System.Collections.Concurrent
{
/// <summary>
/// Provides a thread-safe dictionary for use with data binding.
/// </summary>
/// <typeparam name="TKey">Specifies the type of the keys in this collection.</typeparam>
/// <typeparam name="TValue">Specifies the type of the values in this collection.</typeparam>
[DebuggerDisplay("Count={Count}")]
public class ObservableConcurrentDictionary<TKey, TValue> :
ICollection<KeyValuePair<TKey, TValue>>, IDictionary<TKey, TValue>,
INotifyCollectionChanged, INotifyPropertyChanged
{
private readonly SynchronizationContext _context;
private readonly ConcurrentDictionary<TKey, TValue> _dictionary;
/// <summary>
/// Initializes an instance of the ObservableConcurrentDictionary class.
/// </summary>
public ObservableConcurrentDictionary()
{
_context = AsyncOperationManager.SynchronizationContext;
_dictionary = new ConcurrentDictionary<TKey, TValue>();
}
/// <summary>Event raised when the collection changes.</summary>
public event NotifyCollectionChangedEventHandler CollectionChanged;
/// <summary>Event raised when a property on the collection changes.</summary>
public event PropertyChangedEventHandler PropertyChanged;
/// <summary>
/// Notifies observers of CollectionChanged or PropertyChanged of an update to the dictionary.
/// </summary>
private void NotifyObserversOfChange()
{
var collectionHandler = CollectionChanged;
var propertyHandler = PropertyChanged;
if (collectionHandler != null || propertyHandler != null)
{
_context.Send(s =>
{
collectionHandler?.Invoke(this, new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
propertyHandler?.Invoke(this, new PropertyChangedEventArgs("Count"));
propertyHandler?.Invoke(this, new PropertyChangedEventArgs("Keys"));
propertyHandler?.Invoke(this, new PropertyChangedEventArgs("Values"));
}, null);
}
}
/// <summary>
/// Notifies observers of CollectionChanged or PropertyChanged of an update to the dictionary.
/// </summary>
/// <param name="actionType">Add or Update action</param>
/// <param name="changedItem">The item involved with the change</param>
private void NotifyObserversOfChange(NotifyCollectionChangedAction actionType, object changedItem)
{
var collectionHandler = CollectionChanged;
var propertyHandler = PropertyChanged;
if (collectionHandler != null || propertyHandler != null)
{
_context.Send(s =>
{
collectionHandler?.Invoke(this, new NotifyCollectionChangedEventArgs(actionType, changedItem));
propertyHandler?.Invoke(this, new PropertyChangedEventArgs("Count"));
propertyHandler?.Invoke(this, new PropertyChangedEventArgs("Keys"));
propertyHandler?.Invoke(this, new PropertyChangedEventArgs("Values"));
}, null);
}
}
/// <summary>
/// Notifies observers of CollectionChanged or PropertyChanged of an update to the dictionary.
/// </summary>
/// <param name="actionType">Remove action or optionally an Add action</param>
/// <param name="item">The item in question</param>
/// <param name="index">The position of the item in the collection</param>
private void NotifyObserversOfChange(NotifyCollectionChangedAction actionType, object item, int index)
{
var collectionHandler = CollectionChanged;
var propertyHandler = PropertyChanged;
if (collectionHandler != null || propertyHandler != null)
{
_context.Send(s =>
{
collectionHandler?.Invoke(this, new NotifyCollectionChangedEventArgs(actionType, item, index));
propertyHandler?.Invoke(this, new PropertyChangedEventArgs("Count"));
propertyHandler?.Invoke(this, new PropertyChangedEventArgs("Keys"));
propertyHandler?.Invoke(this, new PropertyChangedEventArgs("Values"));
}, null);
}
}
/// <summary>Attempts to add an item to the dictionary, notifying observers of any changes.</summary>
/// <param name="item">The item to be added.</param>
/// <returns>Whether the add was successful.</returns>
private bool TryAddWithNotification(KeyValuePair<TKey, TValue> item)
=> TryAddWithNotification(item.Key, item.Value);
/// <summary>Attempts to add an item to the dictionary, notifying observers of any changes.</summary>
/// <param name="key">The key of the item to be added.</param>
/// <param name="value">The value of the item to be added.</param>
/// <returns>Whether the add was successful.</returns>
private bool TryAddWithNotification(TKey key, TValue value)
{
bool result = _dictionary.TryAdd(key, value);
int index = IndexOf(key);
if (result) NotifyObserversOfChange(NotifyCollectionChangedAction.Add, value, index);
return result;
}
/// <summary>Attempts to remove an item from the dictionary, notifying observers of any changes.</summary>
/// <param name="key">The key of the item to be removed.</param>
/// <param name="value">The value of the item removed.</param>
/// <returns>Whether the removal was successful.</returns>
private bool TryRemoveWithNotification(TKey key, out TValue value)
{
int index = IndexOf(key);
bool result = _dictionary.TryRemove(key, out value);
if (result) NotifyObserversOfChange(NotifyCollectionChangedAction.Remove, value, index);
return result;
}
/// <summary>Attempts to add or update an item in the dictionary, notifying observers of any changes.</summary>
/// <param name="key">The key of the item to be updated.</param>
/// <param name="value">The new value to set for the item.</param>
/// <returns>Whether the update was successful.</returns>
private void UpdateWithNotification(TKey key, TValue value)
{
_dictionary[key] = value;
NotifyObserversOfChange(NotifyCollectionChangedAction.Replace, value);
}
/// <summary>
/// WPF requires that the reported index for Add/Remove events are correct/reliable. With a dictionary there
/// is no choice but to brute-force search through the key list. Ugly.
/// </summary>
private int IndexOf(TKey key)
{
var keys = _dictionary.Keys;
int index = -1;
foreach(TKey k in keys)
{
index++;
if (k.Equals(key)) return index;
}
return -1;
}
// ICollection<KeyValuePair<TKey,TValue>> Members
void ICollection<KeyValuePair<TKey, TValue>>.Add(KeyValuePair<TKey, TValue> item)
=> TryAddWithNotification(item);
void ICollection<KeyValuePair<TKey, TValue>>.Clear()
{
_dictionary.Clear();
NotifyObserversOfChange();
}
bool ICollection<KeyValuePair<TKey, TValue>>.Contains(KeyValuePair<TKey, TValue> item)
=> ((ICollection<KeyValuePair<TKey, TValue>>)_dictionary).Contains(item);
void ICollection<KeyValuePair<TKey, TValue>>.CopyTo(KeyValuePair<TKey, TValue>[] array, int arrayIndex)
=> ((ICollection<KeyValuePair<TKey, TValue>>)_dictionary).CopyTo(array, arrayIndex);
int ICollection<KeyValuePair<TKey, TValue>>.Count
{
get => _dictionary.Count;
}
bool ICollection<KeyValuePair<TKey, TValue>>.IsReadOnly
{
get => ((ICollection<KeyValuePair<TKey, TValue>>)_dictionary).IsReadOnly;
}
bool ICollection<KeyValuePair<TKey, TValue>>.Remove(KeyValuePair<TKey, TValue> item)
=> TryRemoveWithNotification(item.Key, out TValue temp);
// IEnumerable<KeyValuePair<TKey,TValue>> Members
IEnumerator<KeyValuePair<TKey, TValue>> IEnumerable<KeyValuePair<TKey, TValue>>.GetEnumerator()
=> _dictionary.GetEnumerator();
IEnumerator IEnumerable.GetEnumerator()
=> _dictionary.GetEnumerator();
// IDictionary<TKey,TValue> Members
public void Add(TKey key, TValue value)
=> TryAddWithNotification(key, value);
public bool ContainsKey(TKey key)
=> _dictionary.ContainsKey(key);
public ICollection<TKey> Keys
{
get { return _dictionary.Keys; }
}
public bool Remove(TKey key)
=> TryRemoveWithNotification(key, out TValue temp);
public bool TryGetValue(TKey key, out TValue value)
=> _dictionary.TryGetValue(key, out value);
public ICollection<TValue> Values
{
get => _dictionary.Values;
}
public TValue this[TKey key]
{
get => _dictionary[key];
set => UpdateWithNotification(key, value);
}
}
}
Как я могу это использовать? Есть ли пример?
Мне удалось найти решение - обходное решение
public delegate void CollectionAlteredEventHander( object sender , EventArgs e);
public partial class ObservableDictionary<TKey, TValue> : Dictionary<TKey, TValue>
{
/*Class contructors*/
public event CollectionAlteredEventHander CollectionAltered;
public new TValue this[TKey key]
{
get
{
return base[key];
}
set
{
OnCollectionAltered(new EventArgs());
base[key] = value;
}
}
public new void Add(TKey key, TValue value)
{
int idx = 0;
if (!TryGetKeyIndex(this, key, ref idx))
{
base.Add(key, value);
OnCollectionAltered(new EventArgs());
}
}
public new bool Remove(TKey key)
{
int idx = 0;
if( TryGetKeyIndex( this ,key, ref idx))
{
OnCollectionAltered(new EventArgs());
return base.Remove(key);
}
return false;
}
private bool TryGetKeyIndex(ObservableDictionary<TKey, TValue> observableDictionary, TKey key , ref int idx)
{
foreach (KeyValuePair<TKey, TValue> pair in observableDictionary)
{
if (pair.Key.Equals(key))
{
return true;
}
idx++;
}
return false;
}
public new void Clear()
{
OnCollectionAltered(new EventArgs());
base.Clear();
}
protected virtual void OnCollectionAltered(EventArgs e)
{
if (CollectionAltered != null)
{
CollectionAltered(this, e);
}
}
}
Я больше не реализовал интерфейс INotifyCollectionChanged.