如何在数据库实体的子模型上使用自定义验证属性？

Question

总结：

我希望数据注释验证器在同一个 class (TitleAuthorAndPublishingConfiguration) 中引用另一个属性。

但是，DB.SaveChanges() 并未直接在此 class 上调用。而是在此 class (WebsiteConfiguration) 的父级上调用它。

因此 validationContext.ObjectType 返回 WebsiteConfiguration，我无法在数据注释验证器中引用 TitleAuthorAndPublishingConfiguration 的属性。

WebsiteConfiguration.cs

public class WebsiteConfiguration
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int ID { get; set; }

    public TitleAuthorAndPublishingConfiguration TitleAuthorAndPublishing { get; set; }

    public BookChaptersAndSectionsConfiguration BookChaptersAndSections { get; set; }

    public SocialMediaLoginsConfiguration SocialMediaLogins { get; set; }

    public TagGroupsConfiguration TagGroups { get; set; }
}

public class TitleAuthorAndPublishingConfiguration 
{
    public string BookTitle { get; set; }

    public bool IsPublished { get; set; }

    // how do I access a property of current model when calling DB.SaveChanges() on parent?
    [RequiredIfOtherFieldIsEnabled("IsPublished")]
    public string Publisher { get; set; }
}

// ... and other sub models...

ApplicationDbContext.cs

DbSet<WebsiteConfiguration> WebsiteConfiguration {get;set;}

示例更新代码

    public void SeedWebsiteConfiguration()
    {
        var titleAuthorAndPublishingConfiguration = new TitleAuthorAndPublishingConfiguration()
        {
            // seed values
        };
        var bookChaptersAndSectionsConfiguration = new BookChaptersAndSectionsConfiguration()
        {
            // seed values
        };
        var socialMediaLoginConfiguration = new SocialMediaLoginsConfiguration()
        {
            // seed values
        };
        var tagGroupsConfiguration = new TagGroupsConfiguration()
        {
            // seed values
        };
        var websiteConfiguration = new WebsiteConfiguration()
        {
            TitleAuthorAndPublishing = titleAuthorAndPublishingConfiguration,
            BookChaptersAndSections = bookChaptersAndSectionsConfiguration,
            SocialMediaLogins = socialMediaLoginConfiguration,
            TagGroups = tagGroupsConfiguration
        };
        DB.WebsiteConfiguration.Add(websiteConfiguration);
        DB.SaveChanges();
    }

验证码

public class RequiredIfOtherFieldIsEnabledAttribute : ValidationAttribute
{
    private string _ifWhatIsEnabled { get; set; }


    public RequiredIfOtherFieldIsEnabledAttribute(string IfWhatIsEnabled)
    {
        _ifWhatIsEnabled = IfWhatIsEnabled;
    }

    protected override ValidationResult IsValid(object currentPropertyValue, ValidationContext validationContext)
    {
        var isEnabledProperty = validationContext.ObjectType.GetProperty(_ifWhatIsEnabled);
        if (isEnabledProperty == null)
        {
            return new ValidationResult(
                string.Format("Unknown property: {0}", _ifWhatIsEnabled)
            );
        }
        var isEnabledPropertyValue = (bool)isEnabledProperty.GetValue(validationContext.ObjectInstance, null);

        if (isEnabledPropertyValue == true)
        {
            if (String.IsNullOrEmpty(currentPropertyValue.ToString()))
            {
                return new ValidationResult(String.Format("This field is required if {0} is enabled", isEnabledProperty));
            }
        }
        return ValidationResult.Success;
    }
}

问题

我有办法从 validationContext 访问子模型属性吗？
我的方法被误导了吗？有没有更好的方法将多个模型作为一个更大模型的一部分存储在单个数据库中 table？

我希望不要有多个配置 table 和对数据库的调用。（本例中有4个子模型，下个app可能有10+个）

上面的设置在很多方面满足了我的需求。但是我不想放弃DataAnnotations在子模型上的功能！

加分题

我遇到过一些这样的帖子： How can I tell the Data Annotations validator to also validate complex child properties?

但那已经是 4 岁了，我想知道从那时起是否有任何改变。

我是否在尝试做一些基本上不可能（或至少非常困难）的事情？

Answer 1

Am I trying to do something that is basically impossible (or at least very difficult)?

不，有一个非常简单的解决方案，可以使用 DataAnnotations 与框架和技术完美集成。

您可以创建一个由 EF 验证调用的自定义 ValidationAttribute，并在其中调用 Validator.TryValidateObject。这样，当 EF 调用 CustomValidation.IsValid 时，您可以手动启动子复杂对象验证，依此类推整个对象图。作为奖励，由于 CompositeValidationResult.

，您可以收集所有错误

即

using System;
using System.ComponentModel.DataAnnotations;
using System.Collections.Generic;

public class Program
{
    public static void Main() {
   var person = new Person {
      Address = new Address {
         City = "SmallVille",
         State = "TX",
         Zip = new ZipCode()
      },
      Name = "Kent"
   };

   var context = new ValidationContext(person, null, null);
   var results = new List<ValidationResult>();

   Validator.TryValidateObject(person, context, results, true);

   PrintResults(results, 0);

   Console.ReadKey();
}

private static void PrintResults(IEnumerable<ValidationResult> results, Int32 indentationLevel) {
   foreach (var validationResult in results) {
      Console.WriteLine(validationResult.ErrorMessage);
      Console.WriteLine();

      if (validationResult is CompositeValidationResult) {
         PrintResults(((CompositeValidationResult)validationResult).Results, indentationLevel + 1);
      }
   }
}

}

public class ValidateObjectAttribute: ValidationAttribute {
   protected override ValidationResult IsValid(object value, ValidationContext validationContext) {
      var results = new List<ValidationResult>();
      var context = new ValidationContext(value, null, null);

      Validator.TryValidateObject(value, context, results, true);

      if (results.Count != 0) {
         var compositeResults = new CompositeValidationResult(String.Format("Validation for {0} failed!", validationContext.DisplayName));
         results.ForEach(compositeResults.AddResult);

         return compositeResults;
      }

      return ValidationResult.Success;
   }
}

public class CompositeValidationResult: ValidationResult {
   private readonly List<ValidationResult> _results = new List<ValidationResult>();

   public IEnumerable<ValidationResult> Results {
      get {
         return _results;
      }
   }

   public CompositeValidationResult(string errorMessage) : base(errorMessage) {}
   public CompositeValidationResult(string errorMessage, IEnumerable<string> memberNames) : base(errorMessage, memberNames) {}
   protected CompositeValidationResult(ValidationResult validationResult) : base(validationResult) {}

   public void AddResult(ValidationResult validationResult) {
      _results.Add(validationResult);
   }
}

public class Person {
  [Required]
  public String Name { get; set; }

  [Required, ValidateObject]
  public Address Address { get; set; }
}

public class Address {
  [Required]
  public String Street1 { get; set; }

  public String Street2 { get; set; }

  [Required]
  public String City { get; set; }

  [Required]
  public String State { get; set; }

  [Required, ValidateObject]
  public ZipCode Zip { get; set; }
}

public class ZipCode {
  [Required]
  public String PrimaryCode { get; set; }

  public String SubCode { get; set; }
}

如何在数据库实体的子模型上使用自定义验证属性？

How Can I Use Custom Validation Attributes on Child Models of a DB Entity?

asp.net-mvc

data-annotations

dbcontext