c# 数据标注与数据校验

class Kid
{
 [Range(0, 18)] // 年龄不能超过18岁，不能为负数
 public int Age { get; set; }

 [StringLength(MaximumLength = 50, MinimumLength = 3)] // 名称的长度不能超过 50，不能小于 3
 public string Name { get; set; }

 [DataType(DataType.Date)] // 生日将作为日期展示 (不带时间)
 public DateTime Birthday { get; set; }
}

[AttributeUsage(AttributeTargets.Property, AllowMultiple = false, Inherited = false)]
public class EvenNumberAttribute : ValidationAttribute
{
  public override bool IsValid(object input)
  {
    if (input == null)
      return false;

    if (!int.TryParse(input.ToString(), out int val))
      return false;

    return val % 2 == 0;
  }
}

public class Model
{
  [EvenNumberAttribute(ErrorMessage = "数字必须是偶数")]
  public int MyNumber { get; set; }
}

public class Model
{
  [CustomValidation(typeof(MyCustomValidation), "IsNotEvenNumber")]
  public int MyNumber { get; set; }
}

public static class MyCustomValidation
{
  public static ValidationResult IsNotEvenNumber(object input)
  {
    var result = new ValidationResult("数字必须是偶数");
    if (input == null || !int.TryParse(input.ToString(), out int val))
      return result;
    return val % 2 == 0 ? ValidationResult.Success : result;
  }
}

ValidationContext vc = new ValidationContext(objectToValidate);

ValidationContext vc = new ValidationContext(objectToValidate);
ICollection<ValidationResult> results = new List<ValidationResult>();
bool isValid = Validator.TryValidateObject(objectToValidate, vc, results, true);

ValidationContext vc = new ValidationContext(objectToValidate);
ICollection<ValidationResult> results = new List<ValidationResult>();
bool isValid = Validator.TryValidatePropery(objectToValidate.PropertyToValidate, vc, results, true);