我可以在验证父对象时自动验证复杂的子对象，并将结果包含在已填充的ICollection<ValidationResult>中吗？
如果我运行以下代码：
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
namespace ConsoleApplication1
{
public class Person
{
[Required]
public string Name { get; set; }
public Address Address { get; set; }
}
public class Address
{
[Required]
public string Street { get; set; }
[Required]
public string City { get; set; }
[Required]
public string State { get; set; }
}
class Program
{
static void Main(string[] args)
{
Person person = new Person
{
Name = null,
Address = new Address
{
Street = "123 Any St",
City = "New York",
State = null
}
};
var validationContext = new ValidationContext(person, null, null);
var validationResults = new List<ValidationResult>();
var isValid = Validator.TryValidateObject(person, validationContext, validationResults);
Console.WriteLine(isValid);
validationResults.ForEach(r => Console.WriteLine(r.ErrorMessage));
Console.ReadKey(true);
}
}
}
我得到以下输出：
False
The Name field is required.
但我期待类似的东西：
False
The Name field is required.
The State field is required.
我提供了一个更好的子对象验证解决方案的赏金，但没有得到任何接受者，理想情况下
我仍然对框架不支持这一点感到惊讶。
答案 0 :(得分：25)
不幸的是，这是Validator.TryValidateObject的标准行为
不会递归验证对象的属性值
正如Jeff Handley关于Validating Object and Properties with the Validator的文章所指出的，默认情况下，验证器将按顺序验证：
IValidatableObject 问题是，在每一步......
如果任何验证器无效，
Validator.ValidateObject将中止验证并返回失败
另一个可能的问题是模型绑定器仅对已决定绑定的对象运行验证。例如，如果不为模型上的复杂类型中的字段提供输入，则模型绑定器根本不需要检查这些属性，因为它没有在这些对象上调用构造函数。根据Brad Wilson关于Input Validation vs. Model Validation in ASP.NET MVC的伟大文章：
我们没有递归地“潜入”Address对象的原因是表单中没有任何内容绑定Address中的任何值。
解决此问题的一种方法是通过向属性添加自定义验证属性，将对象级验证转换为属性级别验证，该属性将返回对象本身的验证结果。
Josh Carroll关于Recursive Validation Using DataAnnotations的文章提供了一个这样的策略的实现（最初在this SO question）。如果我们想要验证复杂类型（如Address），我们可以向属性添加自定义ValidateObject属性，因此在第一步中对其进行评估
public class Person {
[Required]
public String Name { get; set; }
[Required, ValidateObject]
public Address Address { get; set; }
}
您需要添加以下 ValidateObjectAttribute 实现：
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);
}
}
对于实现IValidatableObject的对象，当我们检查ModelState时，我们还可以在返回错误列表之前检查模型本身是否有效。我们可以通过调用ModelState.AddModelError(field, error)添加我们想要的任何错误。正如How to force MVC to Validate IValidatableObject中所述，我们可以这样做：
[HttpPost]
public ActionResult Create(Model model) {
if (!ModelState.IsValid) {
var errors = model.Validate(new ValidationContext(model, null, null));
foreach (var error in errors)
foreach (var memberName in error.MemberNames)
ModelState.AddModelError(memberName, error.ErrorMessage);
return View(post);
}
}
，如果您想要更优雅的解决方案，可以通过在{_ 1}}的Application_Start（）中提供自己的自定义模型绑定器实现来编写代码一次。有很好的实施here和here
答案 1 :(得分：9)
我也碰到了这个，发现了这个帖子。这是第一遍：
namespace Foo
{
using System.ComponentModel.DataAnnotations;
using System.Linq;
/// <summary>
/// Attribute class used to validate child properties.
/// </summary>
/// <remarks>
/// See: http://stackoverflow.com/questions/2493800/how-can-i-tell-the-data-annotations-validator-to-also-validate-complex-child-pro
/// Apparently the Data Annotations validator does not validate complex child properties.
/// To do so, slap this attribute on a your property (probably a nested view model)
/// whose type has validation attributes on its properties.
/// This will validate until a nested <see cref="System.ComponentModel.DataAnnotations.ValidationAttribute" />
/// fails. The failed validation result will be returned. In other words, it will fail one at a time.
/// </remarks>
public class HasNestedValidationAttribute : ValidationAttribute
{
/// <summary>
/// Validates the specified value with respect to the current validation attribute.
/// </summary>
/// <param name="value">The value to validate.</param>
/// <param name="validationContext">The context information about the validation operation.</param>
/// <returns>
/// An instance of the <see cref="T:System.ComponentModel.DataAnnotations.ValidationResult"/> class.
/// </returns>
protected override ValidationResult IsValid(object value, ValidationContext validationContext)
{
var isValid = true;
var result = ValidationResult.Success;
var nestedValidationProperties = value.GetType().GetProperties()
.Where(p => IsDefined(p, typeof(ValidationAttribute)))
.OrderBy(p => p.Name);//Not the best order, but at least known and repeatable.
foreach (var property in nestedValidationProperties)
{
var validators = GetCustomAttributes(property, typeof(ValidationAttribute)) as ValidationAttribute[];
if (validators == null || validators.Length == 0) continue;
foreach (var validator in validators)
{
var propertyValue = property.GetValue(value, null);
result = validator.GetValidationResult(propertyValue, new ValidationContext(value, null, null));
if (result == ValidationResult.Success) continue;
isValid = false;
break;
}
if (!isValid)
{
break;
}
}
return result;
}
}
}
答案 2 :(得分：5)
您需要创建自己的验证属性（例如，[CompositeField]）来验证子属性。