我们如何从 ModelState 获取验证规则

Question

是否可以从 ModelState 字典中获取验证规则。例如

我的模型中有以下数据注释属性

[StringLength(64, MinimumLength = 8, ErrorMessage = "{0} must be between {2} to {1} characters")]
public string Password { get; set; }

那么在验证 Modelstate 时我们可以得到 MinimumLength 和 MaximumLenght 吗？

我想发送这两个值作为响应，以便前端可以使用这些值生成本地化消息。

我的回复示例如下

{
  "errorCode" : 1234,
  "message": : "Password must be between 8 to 64 characters",
  "args" : ["8","64"]
}

因此使用此错误代码前端可以使用 args.

生成本地化消息

Answer 1

So while validating Modelstate can we get MinimumLength and MaximumLenght?

您可以使用 Reflection 从模型类型中获取属性值。

var type = ViewModel.GetType()
var properties = type.GetProperties();
foreach (var property in properties)
    {
        var attributes = property.GetCustomAttributes(true);
        foreach (object attribute in attributes)
        {
            var stringLengthAttribute = attribute as StringLengthAttribute;
            if (stringLengthAttribute == null)
            {
              continue;
            }

            var maximumLength = stringLengthAttribute.MaximumLength;
            var minimumLength = stringLengthAttribute.MinimumLength;
        }
    }

Answer 2

即使我们添加也很难做到这一点 ConfigureApiBehaviorOptions 对象不包含验证规则我建议最简单的方法是在你的字符串中创建一个 json 对象，这样你可以直接使用你想要的格式

 [StringLength(64, MinimumLength = 8, ErrorMessage = "{{error:'{0} must be between {2} to {1} characters ',args:'[{1},{2}]' }}") ]

Answer 3

您可以使用 Reflection 来实现您的要求，如@Józef Podlecki 所说。

也可以参考this.

下面是实现它的通用方法：

  public class PerInfo
    {
        [StringLength(64, MinimumLength = 8, ErrorMessage = "{0} must be between {2} to {1} characters")]
        public string Password { get; set; }
    }

作为您提供的响应格式，您可以创建一个错误模型：

 public class CusError
    {
        public long errorCode { get; set; }
        public string message { get; set; }
        public string[] args { get; set; }
    }

代码：

 [HttpPost]
        public IActionResult Validate(PerInfo perInfo)
        {
            if (!ModelState.IsValid)
            {
                var error = GenerateValidationModel<PerInfo>();
                return BadRequest(error);
            }
            return Ok();
        }

        private CusError GenerateValidationModel<T>()
        {
            var error = new CusError();
            foreach (var prop in typeof(T).GetProperties())
            {
                object[] attrs = prop.GetCustomAttributes(true);
                if (attrs == null || attrs.Length == 0)
                    continue;
                foreach (Attribute attr in attrs)
                {
                    if (attr is StringLengthAttribute)
                    {
                        error.errorCode = 1234;
                        error.message = string.Format((attr as StringLengthAttribute).ErrorMessage, prop.Name, (attr as StringLengthAttribute).MaximumLength.ToString(), (attr as StringLengthAttribute).MinimumLength.ToString());
                        error.args = new string[] { (attr as StringLengthAttribute).MinimumLength.ToString(), (attr as StringLengthAttribute).MaximumLength.ToString() };
                    }

                }
            }
            return error;
        }

这里是邮递员的测试结果：

我们如何从 ModelState 获取验证规则

How we can fetch validation rule from ModelState

c#

asp.net-core

data-annotations

asp.net-core-3.1

modelstate