如何直接在模型中使用數據註釋

Question

我在一個項目Csharp MVVM，我想知道是否有可能在模型中使用Data.Annotations，而不是ViewModels。如果是這樣如何？

我想這樣的， 我的模型（類票）：

[Dapper.Key] 
[Required(ErrorMessage = "This field is requierd")] 
[Range(1, int.MaxValue, ErrorMessage ="Only Int")] 
public int? Tic_Id { get; set; } 

[Required(ErrorMessage = "This field is requierd")] 
public DateTime Tic_Date { get; set; } 

我的視圖模型（使用IDataErrorInfo的）：

[RaisePropertyChanged] 
    public virtual Ticket FicheItem {get;set;} 

而且我查看

<!-- ID --> 
     <TextBlock Grid.Row="1" Text="ID :" Style="{StaticResource FicheLabelStyle}"/> 
     <TextBox Name="ID" Grid.Row="1" Grid.Column="1" 
        IsEnabled="True" 
        Text="{Binding FicheItem.Tic_Id, UpdateSourceTrigger=PropertyChanged,ValidatesOnDataErrors=True,NotifyOnValidationError=True,Mode=TwoWay}" 
        Style="{StaticResource FicheTextboxStyleNumber}"/> 
     <TextBlock Grid.Column="1" Grid.Row="2" Name="IDError" Text="{Binding (Validation.Errors)[0].ErrorContent, ElementName=ID}" Foreground="Red" Margin="19,3,0,0" 
        Visibility="{Binding ElementName=IDError, Path=Text,Converter={StaticResource FicheErrorVisibilityConverter},Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}"/> 


     <!-- Date --> 
     <TextBlock Grid.Row="3" Text="Date :" Style="{StaticResource FicheLabelStyle}"/> 
     <TextBox Grid.Row="3" Grid.Column="1" Name="Date" 
       Text="{Binding FicheItem.Tic_Date, ValidatesOnDataErrors=True, NotifyOnValidationError=True,UpdateSourceTrigger=PropertyChanged}" 
       Style="{StaticResource FicheTextboxStyleText}" /> 
     <TextBlock Grid.Column="1" Grid.Row="4" Name="DateError" Text="{Binding (Validation.Errors)[0].ErrorContent, ElementName=Date}" Foreground="Red" Margin="19,3,0,0" 
        Visibility="{Binding ElementName=DateError, Path=Text,Converter={StaticResource FicheErrorVisibilityConverter},Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}"/> 

但不起作用...

Answer 1

您必須在Ticket類上實現IDataErrorInfo接口。然後在索引屬性this[string propertyName]中，您可以使用Validator.TryValidateProperty方法和ValidationContext。

public class Ticket : IDataErrorInfo 
{ 
    [Required(ErrorMessage = "This field is required")] 
    [Range(1, int.MaxValue, ErrorMessage = "Only Int")] 
    public int? Tic_Id { get; set; } 

    [Required(ErrorMessage = "This field is required")] 
    public DateTime? Tic_Date { get; set; } 

    string IDataErrorInfo.Error 
    { 
     get 
     { 
      /* It can be improved */   
      return String.Empty; 
     } 
    } 

    string IDataErrorInfo.this[string propertyName] 
    { 
     get 
     { 
      Type objectType = GetType(); 
      PropertyInfo propertyInfo = objectType.GetProperty(propertyName); 
      object propertyValue = propertyInfo.GetValue(this, null); 
      List<System.ComponentModel.DataAnnotations.ValidationResult> results 
       = new List<System.ComponentModel.DataAnnotations.ValidationResult>(); 

      ValidationContext validationContext = 
       new System.ComponentModel.DataAnnotations.ValidationContext(this, null, null); 
      validationContext.MemberName = propertyName; 

      return Validator.TryValidateProperty(propertyValue, validationContext, results) ? 
       String.Empty : results[0].ErrorMessage; 
     } 
    } 
}