Question

我想在没有行的情况下在DataGrid周围放置一个红色边框（我正在对ItemsSource进行绑定）。

所以我遵循WPF验证指南：

http://www.codeproject.com/Articles/15239/Validation-in-Windows-Presentation-Foundation

无论如何，当Text = ""：

时，使文本框出现这样的错误很简单

empty textbox error

甚至自定义错误：

green

我尝试过调试，并且永远不会调用绑定在我的ItemsSource中的ValidationRules。

<DataGrid ...>
 <DataGrid.ItemsSource>
   <Binding Path="Lines" Mode="TwoWay" UpdateSourceTrigger="PropertyChanged">
       <Binding.ValidationRules>
         <DataGridValidationRule
               MiniumRows="1"
               MaximumRows="100"
               ErrorMessage="must have between 1 and 100 rows">
         </DataGridValidationRule>
       </Binding.ValidationRules>
     </Binding>
 </DataGrid.ItemsSource>
</DataGrid>

然后DataGridValidtionRule类如下所示：

public class  public class StringRangeValidationRule : ValidationRule
{
    private int _minimumRows = -1;
    private int _maximumRows = -1;
    private string _errorMessage;

    public int MinimumRows
    {
        get { return _minimumRows ; }
        set { _minimumRows  = value; }
    }

    public int MaximumRows
    {
        get { return _maximumLength; }
        set { _maximumLength = value; }
    }

    public string ErrorMessage
    {
        get { return _errorMessage; }
        set { _errorMessage = value; }
    }

    public override ValidationResult Validate(object value, 
        CultureInfo cultureInfo)
    {
        ValidationResult result = new ValidationResult(true, null);
        ObservableCollection<Lines> lines = (ObservableCollection<Lines>) value;
        if (lines.Count < this.MinimumRows||
               (this.MaximumRows> 0 &&
                lines.Count > this.MaximumRows))
        {
            result = new ValidationResult(false, this.ErrorMessage);
        }
        return result;
    }

和“行”类

 public class Line
  {
    public Line(string f, string b)
    {
      foo = f;
      bar = b;
    }
   public string Foo {get; set;}
   public string Bar {get; set;}
  }

编辑：

事实证明，我的数据网格的“删除行”按钮是从ObservableCollection删除而不是通过实际的DataGrid（它在ViewModel中删除）...并且由于某种原因这会阻止验证被调用的电话。

再次查看：

<DataGrid Name="mygrid">
 <DataGrid.ItemsSource>
   <Binding Path="Lines" Mode="TwoWay" UpdateSourceTrigger="PropertyChanged">
       <Binding.ValidationRules>
         <DataGridValidationRule
               MiniumRows="1"
               MaximumRows="100"
               ErrorMessage="must have between 1 and 100 rows">
         </DataGridValidationRule>
       </Binding.ValidationRules>
     </Binding>
 </DataGrid.ItemsSource>
</DataGrid>

所以，如果我在ViewModel中：

void delete(Line l)
{
  Lines.Remove(l); //if you delete everything (grid empty) there won't be any error shown.
}

错误边框＆amp;图标不会显示在数据网格周围。

但是如果我把一个直接改变了ItemsSource的事件放在这样：

 void delete(Line l)
    {
      Lines.Remove(l);
      myView.mygrid.ItemsSource = Lines; // this magically fixes everything... even though it was already bound to Lines... though i hate to directly access the View from within the ViewModel.
    }

我不确定为什么......但是那就修好了。关于如何将视图与VM分开的任何想法？我真的不喜欢这个修复。

Answer 1

尝试将数据网格放入边框并为其附加触发器，以便在数据网格为空时将其设为红色

<Border Margin="20" >
    <Border.Style>
        <Style TargetType="Border">
            <Style.Triggers>
                <DataTrigger  Binding="{Binding ISEmpty}" Value="True">
                    <Setter Property="BorderThickness" Value="2" />
                    <Setter Property="BorderBrush" Value="Red" />
                </DataTrigger>
            </Style.Triggers>
        </Style>
    </Border.Style>
    <DataGrid  Name="myGrid" AutoGenerateColumns="True"  ItemsSource="{Binding Path=Lecturers}" >

    </DataGrid>
</Border>

清除网格时将IsEmpty属性设置为true

private bool iSEmpty;

public bool ISEmpty
{
    get { return iSEmpty; }
    set
    {
        iSEmpty = value;
        NotifyPropertyChanged("ISEmpty");
    }
}

清除商品来源收藏

viewmodel.Lecturers.Clear();
this.viewmodel.ISEmpty = true;

未来的工作。您可以将触发器绑定到数据网格控件。

ItemsSource上的WPF Datagrid ValidationRules

1 个答案: