WPF数据验证
1、ValidationRule 验证
ValidationRule:是通过ValidationRule中的的Validate方法来验证我们绑定的属性。所以我们的用法是继承ValidationRule,重写他的Validate方法。示例
public class RequiredRule : ValidationRule
{
public override ValidationResult Validate(object value, CultureInfo cultureInfo)
{
if (value == null)
return new ValidationResult(false, "不能为空值!");
if (string.IsNullOrEmpty(value.ToString()))
return new ValidationResult(false, "不能为空字符串!");
return new ValidationResult(true, null);
}
}
而XAML中需要把错误信息显示出来。
<Window.Resources>
<ControlTemplate x:Key="ErrorTemplate">
<Border BorderBrush="Red" BorderThickness="1">
<AdornedElementPlaceholder/>
</Border>
</ControlTemplate>
<Style TargetType="TextBox">
<Setter Property="Validation.ErrorTemplate" Value="{StaticResource ErrorTemplate}">
</Setter>
<Style.Triggers>
<Trigger Property="Validation.HasError" Value="True">
<Setter Property="ToolTip" Value="{Binding RelativeSource={RelativeSource Self}, Path=(Validation.Errors)[0].ErrorContent}"/>
</Trigger>
</Style.Triggers>
</Style>
</Window.Resources>
<StackPanel>
<TextBlock Text="姓名"/>
<TextBox>
<TextBox.Text>
<Binding Path="Name" UpdateSourceTrigger="PropertyChanged" ValidatesOnDataErrors="True">
<Binding.ValidationRules>
<ValidationRules:RequiredRule/>
</Binding.ValidationRules>
</Binding>
</TextBox.Text>
</TextBox>
<TextBlock Text="年龄"/>
<TextBox >
<TextBox.Text>
<Binding Path="Age" UpdateSourceTrigger="PropertyChanged" ValidatesOnDataErrors="True">
<Binding.ValidationRules>
<ValidationRules:GreaterThanRule Number="10"/>
</Binding.ValidationRules>
</Binding>
</TextBox.Text>
</TextBox>
</StackPanel>
这样显示的错误信息就会以 ToolTip和红色边框的形式显示出来。但这边如果又在TextBox里面设置ToolTip那么就会优先选择TextBox里的,也就是Style中的ToolTip遇到错误信息是不会显示出来的,而是显示TextBox中的ToolTip。所以我们可以改善一下显示的模版来解决这个问题。
<ControlTemplate x:Key="ErrorTemplate">
<DockPanel LastChildFill="true">
<Border Background="Red" DockPanel.Dock="right" Margin="5,0,0,0" Width="20" Height="20" CornerRadius="10"
ToolTip="{Binding ElementName=customAdorner, Path=AdornedElement.(Validation.Errors)[0].ErrorContent}">
<TextBlock Text="!" VerticalAlignment="center" HorizontalAlignment="center" FontWeight="Bold" Foreground="white">
</TextBlock>
</Border>
<AdornedElementPlaceholder Name="customAdorner" VerticalAlignment="Center" >
<Border BorderBrush="red" BorderThickness="1" />
</AdornedElementPlaceholder>
</DockPanel>
</ControlTemplate>
2、Exception 验证
Exception :我们xaml中绑定的对象是属性。所以Exception验证,就是通过属性的改变来判断是否正常。如:
public int Age
{
get { return _age; }
set
{
if (value > 200)
{
throw new Exception("年龄不能大于200");
}
_age = value;
}
}
同样跑出的异常在Xaml中也要显示下。XAML同上。这种方式就会破坏POCO的设计原则。
3、IDataErrorInfo 验证
IDataErrorInfo:这个验证是通过我们的实体对象继承IDataErrorInfo来实现的。这里声明的this索引器来访问类的成员。
public class BaseDataErrorInfo : IDataErrorInfo
{
private string _error;
public string this[string columnName]
{
get { return GetErrorFor(columnName); }
}
public string Error
{
get { return _error; }
set { _error = value; }
}
public virtual string GetErrorFor(string columnName)
{
return string.Empty;
}
}
public class Person : BaseDataErrorInfo { public string Name { get; set; } public override string GetErrorFor(string columnName) { if (columnName == "Name") if (string.IsNullOrEmpty(Name)) return "Name 不能为空"; return base.GetErrorFor(columnName); } }
4、IDataErrorInfo带有数据校验功能的验证
/// <summary> /// 带有数据校验功能的通知基类 /// </summary> public class ViewModelValidationBase : ViewModelBase, IDataErrorInfo { /// <summary> /// 需要校验的属性集合 /// </summary> private List<string> validationKeys = new List<string>(); /// <summary> /// 错误信息字典 /// </summary> private Dictionary<string, string> errorDic = new Dictionary<string, string>(); /// <summary> /// 是否开始校验,以此控制IDataErrorInfo接口校验的时候界面刚初始化即开始校验 /// </summary> public bool IsBeginValidation { get; set; } public string this[string columnName] { get { if (!IsBeginValidation) { return string.Empty; } var vc = new ValidationContext(this, null, null); vc.MemberName = columnName; var res = new List<ValidationResult>(); var result = Validator.TryValidateProperty(this.GetType().GetProperty(columnName).GetValue(this, null), vc, res); if (res.Count > 0) { string errorMessage = string.Join(Environment.NewLine, res.Select(r => r.ErrorMessage).ToArray()); AddErrorDic(columnName, errorMessage); return errorMessage; } RemoveErrorDic(columnName); return string.Empty; } } public string Error => string.Join(Environment.NewLine, errorDic.Values.ToArray()); /// <summary> /// 添加进行校验的属性集合 /// </summary> /// <param name="keys"></param> protected virtual void ValidationKey(string[] keys) { if (keys == null) { return; } foreach (var item in keys) { validationKeys.Add(item); } } /// <summary> /// 强制进行以此校验 /// </summary> protected void Validation() { if (validationKeys != null) { foreach (var item in validationKeys) { RaisePropertyChanged(item); } } } private void AddErrorDic(string key, string value) { if (!errorDic.Keys.Contains(key)) { errorDic.Add(key, value); } } private void RemoveErrorDic(string key) { errorDic.Remove(key); } }
其中ViewModelBase类我使用的是MVVMLight中的通知基类。
使用的时候继承该类,然后使用属性IsBeginValidation控制校验的时机,方法 ValidationKey(string[] keys) 添加需要校验的属性,方法Validation()可以触发校验,属性Error显示校验信息,为空则校验正确,不为空校验错误。
校验规则是使用特性的方式,引用名称空间
using System.ComponentModel.DataAnnotations; /// <summary> /// 获取或设置 /// </summary> private string name; /// <summary> /// 获取或设置 /// </summary> [Required(ErrorMessage = "用户名称不能为空")] public string Name { get { return name; } set { Set<string>(ref name, value, "Name"); } }