当验证规则无效时,WPF MVVMLight Setter不会在绑定TextBox时触发

时间:2017-10-06 10:21:35

标签: wpf validation data-binding mvvm-light validationrules

我有一个TextBox,其绑定在 Mo 属性:

<TextBox>
    <TextBox.Style>
        <Style TargetType="TextBox">
            <Style.Setters>
                <Setter Property="Text">
                    <Setter.Value>
                        <Binding Path="Mo" UpdateSourceTrigger="PropertyChanged">
                            <Binding.ValidationRules>
                                <validator:FloatPositiveValidationRule ValidatesOnTargetUpdated="True" />
                            </Binding.ValidationRules>
                        </Binding>
                    </Setter.Value>
                </Setter>
            </Style.Setters>
        </Style>
    </TextBox.Style>
</TextBox>

这个包含一个验证规则,仅当值不为空且大于0时验证控件:

public class FloatPositiveValidationRule : ValidationRule
{        
    public override ValidationResult Validate(object value, CultureInfo cultureInfo)
    {
        string str = (string)value;

        if (str.Length > 0)
        {
            double mo = Double.Parse(str.Replace(".", ","));

            if (mo > 0)
                return new ValidationResult(true, null);
            else
                return new ValidationResult(false, "Must be greater than 0");
        }
        else
            return new ValidationResult(false, "Empty");
    }
}

在我的视图模型中,当验证为false时,不会触发setter:

private double? _mo;
public string Mo
{
    get { return _mo.ToString(); }

    set
    {
        if (value != "")
            mo = double.Parse(value.Replace(".", ","));

        Set(ref _mo, mo);
    }
}

即使验证无效,是否可以输入设置器?

1 个答案:

答案 0 :(得分:1)

您可以尝试将ValidationStep属性设置为UpdatedValue

<validator:FloatPositiveValidationRule ValidatesOnTargetUpdated="True" ValidationStep="UpdatedValue"  />

这应该在设置了源属性之后运行验证规则

但你真正应该做的是删除ValidationRule并在视图模型中实现验证逻辑,例如通过实现INotifyDataErrorInfo接口。