使用MVVM和entityframework4.0验证WPF用户输入

书库 应用程序示例 WPF Application Framework (WAF)

this book ,第624-625页。

ViewModel应该实现 IDataErrorInfo

private string _newItem;

public string NewItem
        {
            get { return _newItem; }
            set
            {
                if (Equals(_newItem, value)) return;
                _newItem = value;
                SendPropertyChanged("NewItem");
            }
        }

public string this[string propertyName]
        {
            get
            {
                if (propertyName == "NewItem")
                {
                    var valid = NewItem.All(Char.IsLetterOrDigit);
                    if (!valid)
                        return "NewItem can only contain letters and numbers.";
                }
                return null; 
            }
        }

而长版本的视图:

<TextBox>
   <TextBox.Text>
      <Binding UpdateSourceTrigger="PropertyChanged" Path="NewItem">
         <Binding.ValidationRules>
            <DataErrorValidationRule></DataErrorValidationRule>
         </Binding.ValidationRules>
      </Binding>
   </TextBox.Text>
</TextBox>

或简称:

<TextBox Text="{Binding NewItem,UpdateSourceTrigger=PropertyChanged,ValidatesOnDataErrors=True}"/>

MSDN ):

<Window.Resources>
        <Style x:Key="TextBoxInError" TargetType="TextBox">
            <Style.Triggers>
                <Trigger Property="Validation.HasError" Value="true">
                    <Setter Property="ToolTip"
              Value="{Binding RelativeSource={x:Static RelativeSource.Self},
              Path=(Validation.Errors)[0].ErrorContent}"/>
                </Trigger>
            </Style.Triggers>
        </Style>
    </Window.Resources>

然后把这个添加到文本框中:

Style="{StaticResource TextBoxInError}"

干杯!