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silverlight wpf Command提交时输入验证
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silverlight 或WPF在MVVM模式中使用INotifyDataErrorInfo接口对输入进行验证时
控件lostFocus时会触发验证，但在提交动作（例如button的Command）时，不触发
验证。下面的方法提供控件输入验证统一触发。
1、添加ValidationScope类
public class ValidationScope
{
public FrameworkElement ScopeElement { get; private set; } private readonly ObservableCollection<ValidationError> _errors = new ObservableCollection<ValidationError>(); public ObservableCollection<ValidationError> Errors
{
get { return _errors; }
} public bool IsValid()
{
return _errors.Count == ;
} public static string GetValidateBoundProperty(DependencyObject obj)
{
return (string)obj.GetValue(ValidateBoundPropertyProperty);
} public static void SetValidateBoundProperty(DependencyObject obj, string value)
{
obj.SetValue(ValidateBoundPropertyProperty, value);
} public static readonly DependencyProperty ValidateBoundPropertyProperty =
DependencyProperty.RegisterAttached("ValidateBoundProperty", typeof(string), typeof(ValidationScope), new PropertyMetadata(null)); public static ValidationScope GetValidationScope(DependencyObject obj)
{
return (ValidationScope)obj.GetValue(ValidationScopeProperty);
} public static void SetValidationScope(DependencyObject obj, ValidationScope value)
{
obj.SetValue(ValidationScopeProperty, value);
} public static readonly DependencyProperty ValidationScopeProperty =
DependencyProperty.RegisterAttached("ValidationScope", typeof(ValidationScope), typeof(ValidationScope), new PropertyMetadata(null, ValidationScopeChanged)); private static void ValidationScopeChanged(DependencyObject source, DependencyPropertyChangedEventArgs args)
{
ValidationScope oldScope = args.OldValue as ValidationScope;
if (oldScope != null)
{
oldScope.ScopeElement.BindingValidationError -= oldScope.ScopeElement_BindingValidationError;
oldScope.ScopeElement = null;
} FrameworkElement scopeElement = source as FrameworkElement;
if (scopeElement == null)
{
throw new ArgumentException(string.Format(
"'{0}' is not a valid type.ValidationScope attached property can only be specified on types inheriting from FrameworkElement.",
source));
} ValidationScope newScope = (ValidationScope)args.NewValue;
newScope.ScopeElement = scopeElement;
newScope.ScopeElement.BindingValidationError += newScope.ScopeElement_BindingValidationError;
} private void ScopeElement_BindingValidationError(object sender, ValidationErrorEventArgs e)
{
if (e.Action == ValidationErrorEventAction.Removed)
{
Errors.Remove(e.Error);
}
else if (e.Action == ValidationErrorEventAction.Added)
{
Errors.Add(e.Error);
}
} public void ValidateScope()
{
ForEachElement(ScopeElement, delegate(DependencyObject obj)
{
// TODO - some of this reflection could be cached to improve performance
string propertyName = GetValidateBoundProperty(obj);
if (!string.IsNullOrEmpty(propertyName))
{
FrameworkElement element = (FrameworkElement)obj;
var field = element.GetType().GetFields(BindingFlags.Static | BindingFlags.FlattenHierarchy | BindingFlags.Public)
.Where(p => p.FieldType == typeof(DependencyProperty) && p.Name == (propertyName + "Property"))
.FirstOrDefault(); if (field == null)
{
throw new ArgumentException(string.Format(
"Dependency property '{0}' could not be found on type '{1}'; ValidationScope.ValidateBoundProperty",
propertyName, element.GetType()));
}
var be = element.GetBindingExpression((DependencyProperty)field.GetValue(null));
be.UpdateSource();
}
});
} private static void ForEachElement(DependencyObject root, Action<DependencyObject> action)
{
int childCount = VisualTreeHelper.GetChildrenCount(root);
for (int i = ; i < childCount; i++)
{
var obj = VisualTreeHelper.GetChild(root, i);
action(obj);
ForEachElement(obj, action);
}
}
}
2、在包含输入控件的容器控件添加依赖属性ValidationScope（ViewModel里的ValidationScope实例）
xaml:
<containers:ContainerPanel Grid.Row="" Margin="" Title="挂起工单列表" TitleHorizontalAlignment="Left" TitleMargin="10,10,0,10" validation:ValidationScope.ValidationScope="{Binding ValidationScope1}">
3、每个需要验证的控件添加依赖属性ValidateBound，指定要验证控件的哪个属性
<TextBox Text="{Binding ApproveContent,Mode=TwoWay}" validation:ValidationScope.ValidateBoundProperty="Text"/>
4、ViewModel中定义ValidationScope实例
private ValidationScope _validationScope1 = new ValidationScope();
public ValidationScope ValidationScope1
{
get { return _validationScope1; }
set
{
_validationScope1 = value;
this.RaisePropertyChanged(() => ValidationScope1);
}
}
5、在要触发验证的Command中调用验证方法
public DelegateCommand ApproveCommand
{
get
{
if (_approveCommand == null)
{
_approveCommand = new DelegateCommand(() =>
{
ValidationScope1.ValidateScope(); if (!ValidationScope1.IsValid())
{
CommonNotification.Raise(new Notification() { Content = new UWay.NOAP.DTO.MsgInfo() { IsSuccess = true, Content = "要审批的工单需要填写审批内容！" }, Title = "提示" });
}
else
{
ApproveBatch();
} }, () => _canApprove);
}
return _approveCommand;
}
}
