WPF validation (BindingGroup).item[0] return null

本文关键字：return null item validation BindingGroup WPF | 更新日期: 2023-09-27 18:30:54

我正在尝试根据 MSDN 示例 http://msdn.microsoft.com/en-us/library/ee622975（v=vs.110）为我的数据网格进行一些验证.aspx ，

XAML 代码

 <DataGrid x:Name="grdQuoteDetail" Height="319" VerticalAlignment="Top"   DockPanel.Dock="Top" Margin="0,10,0,0" RowEditEnding="grdQuoteDetailSave" CellEditEnding="grdQuoteDetail_CellEditEnding"  AutoGenerateColumns="False">
            <DataGrid.RowValidationRules>
                <local:CourseValidationRule ValidationStep="UpdatedValue"/>
            </DataGrid.RowValidationRules>
            <DataGrid.Columns>
                <DataGridTextColumn Header="No" Binding="{Binding No ,  ValidatesOnExceptions=True}" Width="50"  />
                <DataGridTextColumn Header="Description" Binding="{Binding Description}" Width="*" />
                <DataGridTextColumn Header="Total" Binding="{Binding Total}" Width="120" />
            </DataGrid.Columns>
 </DataGrid>

不同的是我正在使用一个类来生成数据表并将网格的项源设置为它。

CS 代码 

private void genTable()
{     
        dtQuoteDetail.Columns.Add(new DataColumn("No", Type.GetType("System.Int32")));
        dtQuoteDetail.Columns.Add(new DataColumn("Description", Type.GetType("System.String")));
        dtQuoteDetail.Columns.Add(new DataColumn("Total", Type.GetType("System.Double")));
        DataRow dr = dtQuoteDetail.NewRow();
        dr["No"] = 1;
        dr["Description"] = "";
        dr["Total"] = 0;
        dtQuoteDetail.Rows.Add(dr);
        grdQuoteDetail.ItemsSource = dtQuoteDetail.DefaultView;  
}

验证码 

public class CourseValidationRule : ValidationRule
{
    public override ValidationResult Validate(object value, System.Globalization.CultureInfo cultureInfo)
    {
        tblTesting qt = (value as BindingGroup).Items[0] as tblTesting ;  //Return Null 
        if (qt.No > 10)
        {
            return new ValidationResult(false, "This Numbe cannot greater than 10");
        }
        else
        {
            return ValidationResult.ValidResult;
        }
    }
}

用于 tblTesting 的类文件 

 public class tblTesting 
 { 
        public int No {get;set;}
        public string Description {get;set;}
        public double Total {get;set;}
 }

我正在为空

.qt

我不知道为什么，任何指导将不胜感激。

WPF validation (BindingGroup).item[0] return null

因为(value as BindingGroup).Items[0]的类型是'DataRowView'，所以它与你的tblTesting类无关。

您可以获取与 NO 属性对应的第一个单元格的值。

var dataRowView = (value as BindingGroup).Items[0] as DataRowView;
int no = Convert.ToInt32(dataRowView.Row[0]);
if (no > 10)
//do the rest...
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