我理解IValidatableObject是用来验证一个对象的方式，让一个比较彼此的属性。
我仍然希望使用属性来验证单个属性，但我希望在某些情况下忽略某些属性的失败。
我是否试图在下面的情况下错误地使用它?如果不是，我怎么实现这个?
public class ValidateMe : IValidatableObject
{
[Required]
public bool Enable { get; set; }
[Range(1, 5)]
public int Prop1 { get; set; }
[Range(1, 5)]
public int Prop2 { get; set; }
public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
{
if (!this.Enable)
{
/* Return valid result here.
* I don't care if Prop1 and Prop2 are out of range
* if the whole object is not "enabled"
*/
}
else
{
/* Check if Prop1 and Prop2 meet their range requirements here
* and return accordingly.
*/
}
}
}
我实现了一个用于验证的通用抽象类
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
namespace App.Abstractions
{
[Serializable]
abstract public class AEntity
{
public int Id { get; set; }
public IEnumerable<ValidationResult> Validate()
{
var vResults = new List<ValidationResult>();
var vc = new ValidationContext(
instance: this,
serviceProvider: null,
items: null);
var isValid = Validator.TryValidateObject(
instance: vc.ObjectInstance,
validationContext: vc,
validationResults: vResults,
validateAllProperties: true);
/*
if (true)
{
yield return new ValidationResult("Custom Validation","A Property Name string (optional)");
}
*/
if (!isValid)
{
foreach (var validationResult in vResults)
{
yield return validationResult;
}
}
yield break;
}
}
}
首先，感谢@paper1337为我指出了正确的资源……我没有注册，所以我不能投票给他，如果有人读到这篇文章，请这样做。
以下是如何完成我试图做的事情。
Validatable类:
public class ValidateMe : IValidatableObject
{
[Required]
public bool Enable { get; set; }
[Range(1, 5)]
public int Prop1 { get; set; }
[Range(1, 5)]
public int Prop2 { get; set; }
public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
{
var results = new List<ValidationResult>();
if (this.Enable)
{
Validator.TryValidateProperty(this.Prop1,
new ValidationContext(this, null, null) { MemberName = "Prop1" },
results);
Validator.TryValidateProperty(this.Prop2,
new ValidationContext(this, null, null) { MemberName = "Prop2" },
results);
// some other random test
if (this.Prop1 > this.Prop2)
{
results.Add(new ValidationResult("Prop1 must be larger than Prop2"));
}
}
return results;
}
}
如果验证失败，使用Validator.TryValidateProperty()将添加到结果集合中。如果没有失败的验证，则不会向结果集合添加任何东西，这表明验证成功。
进行验证:
public void DoValidation()
{
var toValidate = new ValidateMe()
{
Enable = true,
Prop1 = 1,
Prop2 = 2
};
bool validateAllProperties = false;
var results = new List<ValidationResult>();
bool isValid = Validator.TryValidateObject(
toValidate,
new ValidationContext(toValidate, null, null),
results,
validateAllProperties);
}
要使该方法工作，将validateAllProperties设置为false非常重要。当validateAllProperties为false时，只检查带有[Required]属性的属性。这允许IValidatableObject.Validate()方法处理条件验证。
再补充一点:
因为Validate()方法签名返回IEnumerable<>，该yield返回值可用于延迟生成结果——如果某些验证检查是IO或CPU密集型的，这是有益的。
public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
{
if (this.Enable)
{
// ...
if (this.Prop1 > this.Prop2)
{
yield return new ValidationResult("Prop1 must be larger than Prop2");
}
同样，如果你正在使用MVC ModelState，你可以将验证结果失败转换为ModelState条目，如下所示(如果你在自定义模型绑定器中进行验证，这可能很有用):
var resultsGroupedByMembers = validationResults
.SelectMany(vr => vr.MemberNames
.Select(mn => new { MemberName = mn ?? "",
Error = vr.ErrorMessage }))
.GroupBy(x => x.MemberName);
foreach (var member in resultsGroupedByMembers)
{
ModelState.AddModelError(
member.Key,
string.Join(". ", member.Select(m => m.Error)));
}
可接受的答案的问题是，它现在取决于调用者是否正确验证对象。我要么删除RangeAttribute，并在Validate方法中进行范围验证，要么创建一个自定义属性子类RangeAttribute，将所需属性的名称作为构造函数上的参数。
例如:
[AttributeUsage(AttributeTargets.Property, AllowMultiple = false)]
class RangeIfTrueAttribute : RangeAttribute
{
private readonly string _NameOfBoolProp;
public RangeIfTrueAttribute(string nameOfBoolProp, int min, int max) : base(min, max)
{
_NameOfBoolProp = nameOfBoolProp;
}
public RangeIfTrueAttribute(string nameOfBoolProp, double min, double max) : base(min, max)
{
_NameOfBoolProp = nameOfBoolProp;
}
protected override ValidationResult IsValid(object value, ValidationContext validationContext)
{
var property = validationContext.ObjectType.GetProperty(_NameOfBoolProp);
if (property == null)
return new ValidationResult($"{_NameOfBoolProp} not found");
var boolVal = property.GetValue(validationContext.ObjectInstance, null);
if (boolVal == null || boolVal.GetType() != typeof(bool))
return new ValidationResult($"{_NameOfBoolProp} not boolean");
if ((bool)boolVal)
{
return base.IsValid(value, validationContext);
}
return null;
}
}
我实现了一个用于验证的通用抽象类
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
namespace App.Abstractions
{
[Serializable]
abstract public class AEntity
{
public int Id { get; set; }
public IEnumerable<ValidationResult> Validate()
{
var vResults = new List<ValidationResult>();
var vc = new ValidationContext(
instance: this,
serviceProvider: null,
items: null);
var isValid = Validator.TryValidateObject(
instance: vc.ObjectInstance,
validationContext: vc,
validationResults: vResults,
validateAllProperties: true);
/*
if (true)
{
yield return new ValidationResult("Custom Validation","A Property Name string (optional)");
}
*/
if (!isValid)
{
foreach (var validationResult in vResults)
{
yield return validationResult;
}
}
yield break;
}
}
}
