[英]Binding to a class property in a dictionary in wpf
如果將列表框的ItemsSource
綁定到列表類型的結構,例如具有類類型( List< MyClass>
)的ObservableCollection
(或實際上是任何僅值容器),則可以訪問該類的屬性。
但是如果有一個Dictionary<long, MyClass>
並將itemssource綁定到Dictionary.Values
將無法再訪問該類的屬性。
所以基本上這是我的XAML
<ListBox ItemsSource="{Binding bm.Values}">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel>
<TextBlock Text="{Binding Name}"/>
<TextBlock Text="{Binding Property2}"/>
<TextBlock Text="{Binding Property3}"/>
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
在視圖模型中
public Dictionary<long,MyClass> bm { get; set; }
使用這樣的代碼,您可以將Texblock DataContext設置為MyClass
,但是您無法訪問Name,property2和property3。 但是,如果將字典更改為List,則TextBlock DataContext也將設置為MyClass
,但是它將有權訪問這些字段。
出於體系結構原因,我無法從“詞典”切換到非關鍵集合。
所以問題是:如何使XAML看到屬性,以及為什么這種情況實際上發生了呢?
隨意使用ObservableDictionary類的此代碼
public class ObservableDictionary<TKey, TValue> : IDictionary<TKey, TValue>, INotifyCollectionChanged, INotifyPropertyChanged {
private const string CountString = "Count";
private const string IndexerName = "Item[]";
private const string KeysName = "Keys";
private const string ValuesName = "Values";
private IDictionary<TKey, TValue> _Dictionary;
protected IDictionary<TKey, TValue> Dictionary {
get { return _Dictionary; }
}
#region Constructors
public ObservableDictionary() {
_Dictionary = new Dictionary<TKey, TValue>();
}
public ObservableDictionary(IDictionary<TKey, TValue> dictionary) {
_Dictionary = new Dictionary<TKey, TValue>(dictionary);
}
public ObservableDictionary(IEqualityComparer<TKey> comparer) {
_Dictionary = new Dictionary<TKey, TValue>(comparer);
}
public ObservableDictionary(int capacity) {
_Dictionary = new Dictionary<TKey, TValue>(capacity);
}
public ObservableDictionary(IDictionary<TKey, TValue> dictionary, IEqualityComparer<TKey> comparer) {
_Dictionary = new Dictionary<TKey, TValue>(dictionary, comparer);
}
public ObservableDictionary(int capacity, IEqualityComparer<TKey> comparer) {
_Dictionary = new Dictionary<TKey, TValue>(capacity, comparer);
}
#endregion
#region IDictionary<TKey,TValue> Members
public void Add(TKey key, TValue value) {
Insert(key, value, true);
}
public bool ContainsKey(TKey key) {
return Dictionary.ContainsKey(key);
}
public ICollection<TKey> Keys {
get { return Dictionary.Keys; }
}
public bool Remove(TKey key) {
if(key == null) throw new ArgumentNullException("key");
TValue value;
Dictionary.TryGetValue(key, out value);
var removed = Dictionary.Remove(key);
if(removed)
//OnCollectionChanged(NotifyCollectionChangedAction.Remove, new KeyValuePair<TKey, TValue>(key, value));
OnCollectionChanged();
return removed;
}
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 {
Insert(key, value, false);
}
}
#endregion
#region ICollection<KeyValuePair<TKey,TValue>> Members
public void Add(KeyValuePair<TKey, TValue> item) {
Insert(item.Key, item.Value, true);
}
public void Clear() {
if(Dictionary.Count > 0) {
Dictionary.Clear();
OnCollectionChanged();
}
}
public bool Contains(KeyValuePair<TKey, TValue> item) {
return Dictionary.Contains(item);
}
public void CopyTo(KeyValuePair<TKey, TValue>[] array, int arrayIndex) {
Dictionary.CopyTo(array, arrayIndex);
}
public int Count {
get { return Dictionary.Count; }
}
public bool IsReadOnly {
get { return Dictionary.IsReadOnly; }
}
public bool Remove(KeyValuePair<TKey, TValue> item) {
return Remove(item.Key);
}
#endregion
#region IEnumerable<KeyValuePair<TKey,TValue>> Members
public IEnumerator<KeyValuePair<TKey, TValue>> GetEnumerator() {
return Dictionary.GetEnumerator();
}
#endregion
#region IEnumerable Members
IEnumerator IEnumerable.GetEnumerator() {
return ((IEnumerable) Dictionary).GetEnumerator();
}
#endregion
#region INotifyCollectionChanged Members
public event NotifyCollectionChangedEventHandler CollectionChanged;
#endregion
#region INotifyPropertyChanged Members
public event PropertyChangedEventHandler PropertyChanged;
#endregion
public void AddRange(IDictionary<TKey, TValue> items) {
if(items == null) throw new ArgumentNullException("items");
if(items.Count > 0) {
if(Dictionary.Count > 0) {
if(items.Keys.Any((k) => Dictionary.ContainsKey(k)))
throw new ArgumentException("An item with the same key has already been added.");
else
foreach(var item in items) Dictionary.Add(item);
} else
_Dictionary = new Dictionary<TKey, TValue>(items);
OnCollectionChanged(NotifyCollectionChangedAction.Add, items.ToArray());
}
}
private void Insert(TKey key, TValue value, bool add) {
if(key == null) throw new ArgumentNullException("key");
TValue item;
if(Dictionary.TryGetValue(key, out item)) {
if(add) throw new ArgumentException("An item with the same key has already been added.");
if(Equals(item, value)) return;
Dictionary[key] = value;
OnCollectionChanged(NotifyCollectionChangedAction.Replace, new KeyValuePair<TKey, TValue>(key, value), new KeyValuePair<TKey, TValue>(key, item));
} else {
Dictionary[key] = value;
OnCollectionChanged(NotifyCollectionChangedAction.Add, new KeyValuePair<TKey, TValue>(key, value));
}
}
private void OnPropertyChanged() {
OnPropertyChanged(CountString);
OnPropertyChanged(IndexerName);
OnPropertyChanged(KeysName);
OnPropertyChanged(ValuesName);
}
protected virtual void OnPropertyChanged(string propertyName) {
if(PropertyChanged != null) PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
private void OnCollectionChanged() {
OnPropertyChanged();
if(CollectionChanged != null) CollectionChanged(this, new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
}
private void OnCollectionChanged(NotifyCollectionChangedAction action, KeyValuePair<TKey, TValue> changedItem) {
OnPropertyChanged();
if(CollectionChanged != null) CollectionChanged(this, new NotifyCollectionChangedEventArgs(action, changedItem));
}
private void OnCollectionChanged(NotifyCollectionChangedAction action, KeyValuePair<TKey, TValue> newItem, KeyValuePair<TKey, TValue> oldItem) {
OnPropertyChanged();
if(CollectionChanged != null) CollectionChanged(this, new NotifyCollectionChangedEventArgs(action, newItem, oldItem));
}
private void OnCollectionChanged(NotifyCollectionChangedAction action, IList newItems) {
OnPropertyChanged();
if(CollectionChanged != null) CollectionChanged(this, new NotifyCollectionChangedEventArgs(action, newItems));
}
}
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