雙向綁定需要路徑或XPath，DataGrid的結合

Question

我有一個DataGrid是由用戶，XAML填寫：

<DataGrid ItemsSource="{Binding Path=Input.InloopAangepast, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"> 
    <DataGrid.Columns> 
     <DataGridTextColumn Binding="{Binding Path=TypeOppervlak}"/> 
     <DataGridTextColumn Binding="{Binding Path=TypeAfstroming}"/> 
     <DataGridTextColumn Binding="{Binding Path=Parameters[0].Double}"/> 
     <DataGridTextColumn Binding="{Binding Path=Parameters[1].Double}"/> 
     <DataGridTextColumn Binding="{Binding Path=Parameters[2].Double}"/> 
     <DataGridTextColumn Binding="{Binding Path=Parameters[3].Double}"/> 
     <DataGridTextColumn Binding="{Binding Path=Parameters[4].Double}"/> 
     <DataGridTextColumn Binding="{Binding Path=Parameters[5].Double}"/> 
     <DataGridTextColumn Binding="{Binding Path=Parameters[6].Double}"/> 
    </DataGrid.Columns> 
</DataGrid> 

視圖模型：

InloopAangepast = new ObservableCollection<Inloop>(); 

和：

public class Inloop : INotifyPropertyChanged 
{ 
    public Inloop() 
    { 
     Parameters = new ObservableCollection<InloopParameter>(); 
    } 

    private string _typeOppervlak; 
    private string _typeAfstroming; 
    private string _omschrijving; 
    public ObservableCollection<InloopParameter> _parameters; 

    public string TypeOppervlak 
    { 
     get 
     { 
      return _typeOppervlak; 
     } 
     set 
     { 
      _typeOppervlak = value; 
      if (PropertyChanged != null) 
      { 
       this.PropertyChanged(this, new PropertyChangedEventArgs("TypeOppervlak")); 
      } 
     } 
    } 

    public string TypeAfstroming 
    { 
     get 
     { 
      return _typeAfstroming; 
     } 
     set 
     { 
      _typeAfstroming = value; 
      if (PropertyChanged != null) 
      { 
       this.PropertyChanged(this, new PropertyChangedEventArgs("TypeAfstroming")); 
      } 
     } 
    } 

    public string Omschrijving 
    { 
     get 
     { 
      return _omschrijving; 
     } 
     set 
     { 
      _omschrijving = value; 
      if (PropertyChanged != null) 
      { 
       this.PropertyChanged(this, new PropertyChangedEventArgs("Omschrijving")); 
      } 
     } 
    } 

    public ObservableCollection<InloopParameter> Parameters 
    { 
     get 
     { 
      return _parameters; 
     } 
     set 
     { 
      _parameters = value; 
      if (PropertyChanged != null) 
      { 
       this.PropertyChanged(this, new PropertyChangedEventArgs("Parameters")); 
      } 
     } 
    } 

    public event PropertyChangedEventHandler PropertyChanged; 
} 

public class InloopParameter : INotifyPropertyChanged 
{ 
    public InloopParameter() 
    { 

    } 

    private string _naam; 
    private string _string; 
    private double? _double; 

    public string Naam 
    { 
     get 
     { 
      return _naam; 
     } 
     set 
     { 
      _naam = value; 
      if (PropertyChanged != null) 
      { 
       this.PropertyChanged(this, new PropertyChangedEventArgs("Naam")); 
      } 
     } 
    } 

    public string String 
    { 
     get 
     { 
      return _string; 
     } 
     set 
     { 
      _string = value; 
      if (PropertyChanged != null) 
      { 
       this.PropertyChanged(this, new PropertyChangedEventArgs("String")); 
      } 
     } 
    } 

    public double? Double 
    { 
     get 
     { 
      return _double; 
     } 
     set 
     { 
      _double = value; 
      if (PropertyChanged != null) 
      { 
       this.PropertyChanged(this, new PropertyChangedEventArgs("Double")); 
      } 
     } 
    } 

    public event PropertyChangedEventHandler PropertyChanged; 
} 

我可以輸入前兩個字段（TypeOppervlak和TypeAfstroming），但是當我輸入其他字段之一時出現錯誤「雙向綁定需要Path或XPath「。我究竟做錯了什麼？

Answer 1

您需要初始化列表_parameters以便用戶可以編輯它們。在構造函數初始化：

public Inloop() 
{ 
    _parameters = new ObservableCollection<InloopParameter>(); 
    _parameters.Add(new InloopParameter()); 
    _parameters.Add(new InloopParameter()); 
    _parameters.Add(new InloopParameter()); 
    _parameters.Add(new InloopParameter()); 
    _parameters.Add(new InloopParameter()); 
    _parameters.Add(new InloopParameter()); 
    _parameters.Add(new InloopParameter()); 
} 

您需要在列表中等於你在UI （7個項目要準確）結合指數添加項目。

Answer 2

Parameters屬性爲空。確保將集合分配給構造函數中的屬性。