Xaml双向绑定文本框到可观察的集合 [英] Xaml two way binding of textbox to observable collection

问题描述

在我的WP8应用程序中，我有一个类，它有一个 ObservableCollection< ObservableCollection< int> 属性称为Matrix。

我想使用项目控件显示这些矩阵。

 < ItemsControl ItemsSource ={Binding FirstMatrix.Matrix }> 
< ItemsControl.ItemTemplate> 
< DataTemplate> 
< ItemsControl ItemsSource ={Binding}> 
< ItemsControl.ItemsPanel> 
< ItemsPanelTemplate> 
< StackPanel Orientation =Horizo​​ntal>< / StackPanel> 
< / ItemsPanelTemplate> 
< /ItemsControl.ItemsPanel> 
< ItemsControl.ItemTemplate> 
< DataTemplate> 
< TextBox Text ={Binding}/> 
< / DataTemplate> 
< /ItemsControl.ItemTemplate> 
< / ItemsControl> 
< / DataTemplate> 
< /ItemsControl.ItemTemplate> 
< / ItemsControl> 
  

该代码在显示方面可以工作（它是使用默认值的零填充的）。但是我也想允许在TextBox中进行更改，这将在Matrix属性中反映出来 - 现在TextBox不能被更改，因为它们的值绑定到Matrix单元格的一个方法。我尝试设置< TextBox Text ={Binding Mode = TwoWay}/> 或sth相似，但似乎不起作用。
任何想法应该如何绑定数据？

编辑：
我已经实现了INotifyPropertyChanged。
这是我的课程的一部分：

  public partial class CalcMatrix：INotifyPropertyChanged 
 {
 public ObservableCollection< ObservableCollection< int>> Matrix 
 {
 get {return _matrix; } 
 set 
 {
 _matrix = value; 
 OnPropertyChanged（Matrix）; 
} 
} 
 private ObservableCollection< ObservableCollection< int>> _矩阵; 
 
 private void OnPropertyChanged（string argName）
 {
 var handler = PropertyChanged; 
 if（handler！= null）
处理程序（this，new PropertyChangedEventArgs（argName））; 
} 
 public event PropertyChangedEventHandler PropertyChanged; 
} 
  

我认为TexBoxes不改变的原因是因为绑定是一个 - 文本一直是Matrix中的内容。我相信我应该以某种方式改变XAML绑定到TwoWay或某些东西，但不知道如何。任何想法？

解决方案

双向模式绑定需要路径（为什么？看到这个SO答案），所以你不能像 {Binding Mode = TwoWay} 那样做，它必须像 {Binding SomePath，Mode = TwoWay} 。因此，在这种情况下，您必须将矩阵项包装为一些类而不是纯int，并将该int作为该类的属性的值。

  //您的Matrix属性类型变成：
 ... 
 public ObservableCollection< ObservableCollection< MatrixElement>> Matrix 
 ... 
 
 // MatrixElement类是这样的：
 public class MatrixElement：INotifyPropertyChanged 
 {
 private int _value; 
 public int Value 
 {
 get {return _value; } 
 set {
 _value = value; 
 OnPropertyChanged（Value）; 
} 
} 
 
 .... 
} 
 
 //那么你可以用双向模式绑定TextBox 
 ... 
< ItemsControl.ItemTemplate> 
< DataTemplate> 
< TextBox Text ={Binding Value，Mode = TwoWay}/> 
< / DataTemplate> 
< /ItemsControl.ItemTemplate> 
 ... 
  

In my WP8 app I have a class, which has a ObservableCollection<ObservableCollection<int>> property called Matrix.

I want to display these matrices using items control.

 <ItemsControl ItemsSource="{Binding FirstMatrix.Matrix}">
            <ItemsControl.ItemTemplate>
                <DataTemplate>
                    <ItemsControl ItemsSource="{Binding}">
                        <ItemsControl.ItemsPanel>
                            <ItemsPanelTemplate>
                                <StackPanel Orientation="Horizontal"></StackPanel>
                            </ItemsPanelTemplate>
                        </ItemsControl.ItemsPanel>
                        <ItemsControl.ItemTemplate>
                            <DataTemplate>
                                <TextBox Text="{Binding}" />
                            </DataTemplate>
                        </ItemsControl.ItemTemplate>
                    </ItemsControl>
                </DataTemplate>
            </ItemsControl.ItemTemplate>
        </ItemsControl>

The code works as far as displaying is concerned (it's filled with zeros which is a default value). But I also want to allow changes in TextBoxes which would be reflected in Matrix property - now the TextBoxes can't be changed, because their value is bound one way to Matrix cells I guess. I tried setting <TextBox Text="{Binding Mode=TwoWay}" />or sth similar but it doesn't seem to work. Any ideas how should the data be bound ?

EDIT: I have implemented the INotifyPropertyChanged. Here is a part of my class:

public partial class CalcMatrix : INotifyPropertyChanged
    {
        public ObservableCollection<ObservableCollection<int>> Matrix 
        { 
            get { return _matrix; }
            set
            {
                _matrix = value;
                OnPropertyChanged("Matrix");
            } 
        }
        private ObservableCollection<ObservableCollection<int>> _matrix;

        private void OnPropertyChanged(string argName)
        {
            var handler = PropertyChanged;
            if(handler != null)
                handler(this, new PropertyChangedEventArgs(argName));
        }
        public event PropertyChangedEventHandler PropertyChanged;
    }

I think the reason the TexBoxes don't change is because the binding is one-way - the Text is always what is inside the Matrix. I believe that i should somehow change the XAML binding to TwoWay or something but don't know how. Any ideas ?

解决方案

Two way mode binding require path (why? see this SO answer), so you can't do it just like {Binding Mode=TwoWay}, it has to be something like {Binding SomePath, Mode=TwoWay}. Therefore, in this case you have to wrap matrix item to be some class instead of plain int and put that int as property's value of that class.

//your Matrix property type become:
...
public ObservableCollection<ObservableCollection<MatrixElement>> Matrix
...

//MatrixElement class is something like:
public class MatrixElement : INotifyPropertyChanged
{
    private int _value;
    public int Value
    {
        get { return _value; }
        set { 
                _value = value; 
                OnPropertyChanged("Value"); 
            }
    }

    ....
}

//then you can bind TextBox in two way mode
...
<ItemsControl.ItemTemplate>
    <DataTemplate>
        <TextBox Text="{Binding Value, Mode=TwoWay}" />
    </DataTemplate>
</ItemsControl.ItemTemplate>
...

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