MVVM WPF：驗證自動生成列的數據網格行

Question

我正在創建一個列表存儲在列表中的DataTable。

public class CustomColumn 
{ 
    public string ColumnName { get; set; } 
    public int MinLength { get; set; } 
    public int MaxLength { get; set; } 
} 

public class ViewModel 
{ 
    public List<CustomColumn> Columns { get; set; } 
    public DataTable MyTable { get; set; } 

    public ViewModel() 
    { 
     InitializeCustomColumns(); 
     MyTable = new DataTable(); 

     foreach (CustomColumn column in Columns) 
     { 
      MyTable.Columns.Add(column.ColumnName, typeof(string)); 
     } 
    } 
} 

現在我結合了DataTable爲DataGrid，並允許用戶在DataGrid添加行。我的DataGrid列列是在運行時初始化時自動生成的。當用戶在該行的特定列中輸入某個值時，我想根據CustomColumn屬性 - >MinLength（最小字符串長度）& MaxLength（允許的最大字符串長度）進行驗證。如果驗證失敗，我想顯示DataGrid中出現的默認紅色邊框以顯示無效輸入。我遵循MVVM軟件架構模式。

編輯

我連着ColumnChanging監聽

MyTable.ColumnChanging += tableColumnChanging; 

private void tableColumnChanging(object sender, DataColumnChangeEventArgs e) 
{ 
    //I am able to validate here using my logic 
    if(!isValid(e)) 
    { 
     object badValue = e.ProposedValue; 
     e.ProposedValue = "Bad Data"; 
     e.Row.RowError = "The column contains an error"; 
     e.Row.SetColumnError(e.Column, "Column cannot be " + badValue); 
    } 
    else 
    { 
     ... 
    } 

} 

我能夠證實，但我想我的顯示與細胞！標記isValid是否返回false。

Answer 1

嗯，我設法爲同一

XAML做一個變通方法

<ScrollViewer xmlns:l="clr-namespace:CSharpWPF"> 
    <ScrollViewer.Resources> 
     <DataTemplate DataType="{x:Type l:CustomTable}"> 
      <DataTemplate.Resources> 
       <l:ErrorToVisibilityConverter x:Key="ErrorToVisibilityConverter" /> 
       <Style TargetType="DataGridCell"> 
        <Setter Property="Template"> 
         <Setter.Value> 
          <ControlTemplate TargetType="DataGridCell"> 
           <Grid Background="{TemplateBinding Background}"> 
            <StackPanel Orientation="Horizontal"> 
             <TextBlock Text=" ! " 
                FontWeight="Bold" 
                Foreground="Red"> 
              <TextBlock.Visibility> 
               <MultiBinding Converter="{StaticResource ErrorToVisibilityConverter}" 
                   Mode="OneWay"> 
                <Binding RelativeSource="{RelativeSource FindAncestor,AncestorType=DataGridCell}" /> 
                <Binding Path="Tag.Errors" 
                  RelativeSource="{RelativeSource FindAncestor,AncestorType=DataGrid}" /> 
                <Binding /> 
               </MultiBinding> 
              </TextBlock.Visibility> 
             </TextBlock> 
             <ContentPresenter /> 
            </StackPanel> 
           </Grid> 
          </ControlTemplate> 
         </Setter.Value> 
        </Setter> 
       </Style> 
      </DataTemplate.Resources> 
      <StackPanel> 
       ... 
      </StackPanel> 
     </DataTemplate> 
    </ScrollViewer.Resources> 
    <ContentControl Content="{Binding TableCollection}" /> 
</ScrollViewer> 

我已經添加了DataGridCell一個Style和定義的自定義Template我們額外的元素顯示!馬克

轉換器類

namespace CSharpWPF 
{ 
    public class ErrorToVisibilityConverter : IMultiValueConverter 
    { 
     public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture) 
     { 
      DataGridColumn column = values[0] as DataGridColumn; 
      ObservableCollection<DataColumnChangeEventArgs> errors = values[1] as ObservableCollection<DataColumnChangeEventArgs>; 
      DataRowView view = values[2] as DataRowView; 

      DataColumnChangeEventArgs args = errors.FirstOrDefault(e => (e.Row == view.Row) && (e.Column.Ordinal == column.DisplayIndex)); 

      return view.Row.HasErrors && args != null ? Visibility.Visible : Visibility.Collapsed; 
     } 

     public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture) 
     { 
      throw new NotImplementedException(); 
     } 
    } 
} 

這將檢測如果當前小區是其中受影響的一個，並返回Visibility.Visible如果爲真，否則Visibility.Collapsed因此隱藏或顯示

變化在CustomTable

public CustomTable() 
{ 
    ... 

    Errors = new ObservableCollection<DataColumnChangeEventArgs>(); 
} 

private void tableColumnChanging(object sender, DataColumnChangeEventArgs e) 
{ 
    if (!isValid(e)) 
    { 
     object badValue = e.ProposedValue; 
     e.ProposedValue = "Bad Data"; 
     e.Row.RowError = "The column contains an error"; 
     e.Row.SetColumnError(e.Column, "Column cannot be " + badValue); 
     Errors.Add(e); 
     OnPropertyChanged("Errors"); 
    } 
    else 
    { 
     DataColumnChangeEventArgs args = Errors.FirstOrDefault(ee => (ee.Row == e.Row) && (ee.Column == e.Column)); 
     if (args != null) 
     { 
      Errors.Remove(args); 
      OnPropertyChanged("Errors"); 
     } 
     //... 
    } 
} 

public ObservableCollection<DataColumnChangeEventArgs> Errors { get; set; } 

根據錯誤狀態的額外元件結果

所以整個想法是與通知符添加額外的屬性改變能力並將其用作觸發器和其他屬性來檢測適當的列，而休息是我們額外的可見性！元素在自定義模板