2
我知道有很多关于这个错误的问题（1，2，3，4，5等），但我不能找到一个解释的原因这个错误适合我的情况。让我知道如果我错过了！WPF“EditItem”不允许这种观点
首先，我使用自定义类（不是ObservableCollection或任何其他.NET内置的可观察集合）绑定到我的DataGrid ItemsSource。在向你展示它的代码之前，让我解释我是怎么想的（我的假设可能是错的）。
在我看来，为了可以绑定，集合必须实现至少IEnumerable和INotifyCollectionChanged。 IEnumerable为了使视图获得要显示的项目（感谢GetEnumerator方法）和INotifyCollectionChanged以便视图知道集合上的更改。
所以我结束了这个类：
public class ObservableDictionary<TKey, TValue> : IDictionary<TKey, TValue>, IEnumerable<TValue>, INotifyCollectionChanged
{
#region fields
private IDictionary<TKey, TValue> _innerDictionary;
#endregion
#region properties
public int Count { get { return _innerDictionary.Count; } }
public ICollection<TKey> Keys { get { return _innerDictionary.Keys; } }
public ICollection<TValue> Values { get { return _innerDictionary.Values; } }
public bool IsReadOnly { get { return false; } }
#endregion
#region indexors
public TValue this[TKey key]
{
get { return _innerDictionary[key]; }
set { this.InternalAdd(new KeyValuePair<TKey, TValue>(key, value)); }
}
#endregion
#region events
public event NotifyCollectionChangedEventHandler CollectionChanged;
#endregion
#region constructors
public ObservableDictionary()
{
_innerDictionary = new Dictionary<TKey, TValue>();
}
public ObservableDictionary(int capacity)
{
_innerDictionary = new Dictionary<TKey, TValue>(capacity);
}
public ObservableDictionary(IEqualityComparer<TKey> comparer)
{
_innerDictionary = new Dictionary<TKey, TValue>(comparer);
}
public ObservableDictionary(IDictionary<TKey, TValue> dictionary)
{
_innerDictionary = new Dictionary<TKey, TValue>(dictionary);
}
public ObservableDictionary(int capacity, IEqualityComparer<TKey> comparer)
{
_innerDictionary = new Dictionary<TKey, TValue>(capacity, comparer);
}
public ObservableDictionary(IDictionary<TKey, TValue> dictionary, IEqualityComparer<TKey> comparer)
{
_innerDictionary = new Dictionary<TKey, TValue>(dictionary, comparer);
}
#endregion
#region public methods
public bool ContainsKey(TKey key)
{
return _innerDictionary.ContainsKey(key);
}
public bool Contains(KeyValuePair<TKey, TValue> item)
{
return _innerDictionary.Contains(item);
}
public void Add(TKey key, TValue value)
{
this.InternalAdd(new KeyValuePair<TKey, TValue>(key, value));
}
public void AddRange(IEnumerable<KeyValuePair<TKey, TValue>> items)
{
if (!items.Any())
{
return;
}
var added = new List<TValue>();
var removed = new List<TValue>();
foreach (var item in items)
{
TValue value;
if (_innerDictionary.TryGetValue(item.Key, out value))
{
removed.Add(value);
}
added.Add(item.Value);
_innerDictionary[item.Key] = item.Value;
}
this.CollectionChanged?.Invoke(this, new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Add, added, null));
if (removed.Count > 0)
{
this.CollectionChanged?.Invoke(this, new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Remove, null, removed));
}
}
public void Add(KeyValuePair<TKey, TValue> item)
{
this.InternalAdd(item);
}
public bool TryGetValue(TKey key, out TValue value)
{
return _innerDictionary.TryGetValue(key, out value);
}
public bool Remove(TKey key)
{
return this.InternalRemove(key);
}
public bool Remove(KeyValuePair<TKey, TValue> item)
{
return this.InternalRemove(item.Key);
}
public void Clear()
{
_innerDictionary.Clear();
this.CollectionChanged?.Invoke(this, new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
}
public void CopyTo(KeyValuePair<TKey, TValue>[] array, int arrayIndex)
{
_innerDictionary.CopyTo(array, arrayIndex);
}
public IEnumerator<TValue> GetEnumerator()
{
return Values.GetEnumerator();
}
IEnumerator IEnumerable.GetEnumerator()
{
return this.GetEnumerator();
}
IEnumerator<KeyValuePair<TKey, TValue>> IEnumerable<KeyValuePair<TKey, TValue>>.GetEnumerator()
{
return _innerDictionary.GetEnumerator();
}
#endregion
#region private methods
/// <summary>
/// Adds the specified value to the internal dictionary and indicates whether the element has actually been added. Fires the CollectionChanged event accordingly.
/// </summary>
/// <param name="key"></param>
/// <param name="value"></param>
private void InternalAdd(KeyValuePair<TKey, TValue> item)
{
IList added = new TValue[] { item.Value };
TValue value;
if (_innerDictionary.TryGetValue(item.Key, out value))
{
this.CollectionChanged?.Invoke(this, new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Remove, null, new TValue[] { value }));
}
_innerDictionary[item.Key] = item.Value;
this.CollectionChanged?.Invoke(this, new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Add, added, null));
}
/// <summary>
/// Remove the specified key from the internal dictionary and indicates whether the element has actually been removed. Fires the CollectionChanged event accordingly.
/// </summary>
/// <param name="key"></param>
/// <param name="value"></param>
private bool InternalRemove(TKey key)
{
TValue value;
if (_innerDictionary.TryGetValue(key, out value))
{
_innerDictionary.Remove(key);
this.CollectionChanged?.Invoke(this, new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Remove, null, new TValue[] { value }));
}
return value != null;
}
#endregion
}
它为了实现隐含的IEnumerable<TValue>.GetEnumerator并明确其他GetEnumerator方法（IDictionary和IEnumerable），以我的观点显示我的字典里只有值，和我映射围绕调用CollectionChanged事件的添加/删除方法。
我的视图模型的定义是这样的：
class MyViewModel
{
public ObservableDictionary<string, Foo> Foos { get; private set; }
public MyViewModel()
{
this.Foos = new ObservableDictionary<string, Foo>();
}
}
并将其绑定到我的看法是这样的：
<DataGrid ItemsSource="{Binding Facts}" AutoGenerateColumns="False" CanUserAddRows="False" CanUserDeleteRows="False">
<DataGrid.Columns>
<DataGridTextColumn Header="Name" Binding="{Binding Name}" IsReadOnly="True" Width="*" />
<DataGridTextColumn Header="Type" Binding="{Binding Type}" IsReadOnly="True" Width="*" />
<DataGridTextColumn Header="Value" Binding="{Binding Value}" IsReadOnly="False" Width="*" />
</DataGrid.Columns>
</DataGrid>
然后，当我尝试编辑的价值，我得到指定的错误：
'EditItem' is not allowed for this view
当我在我的代码中放置了一些断点时，我从来没有达到ObservableDictionary indexor setter no r Foo.Value二传手。
我的想法是关于视图如何从绑定集合中获取项目的问题？为什么我得到这个错误和/或我如何授权我的观点为EditItem？如果你希望能够在一个DataGrid编辑数据
[只是一个说明]（https://stackoverflow.com/a/4225429/3283203）关于“我永远不会到达ObservableDictionary indexor setter” – Kilazur