配合ModelState使用，关于使用方法，参考微软文档

https://docs.microsoft.com/en-us/aspnet/web-api/overview/formats-and-model-binding/model-validation-in-aspnet-web-api

自定义Data Annotations只需要继承ValidationAttribute，并且重写IsValid方法。

示例：

// ===================================================================
// ModelState自定义注解
// 多个字段分组判断，全部不允许为空或至少有一个不为空
//====================================================================
// CreateTime：2019-04-24
// Author：liucx
// ===================================================================
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Linq;
using System.Text;
using System.Threading.Tasks;namespace OF.Component.Model
{/// <summary>///  多个属性字段分组不为空判断  传入参数逗号间隔///  <example>[GroupEmpty("p1,p2,p3",false,ErrorMessage="p1p2p3三个参数中至少有一个非空")] </example>/// </summary>public class GroupEmptyAttribute : ValidationAttribute{private readonly string _groupFields;private readonly bool _notNullableAll;/// <summary>///  构造函数/// </summary>/// <param name="groupFields">属性名，多个属性名逗号隔开</param>/// <param name="notNullableAll"> true全部不允许为空。 false只要存在不为空的属性即可</param>public GroupEmptyAttribute(string groupFields, bool notNullableAll){_groupFields = groupFields;_notNullableAll = notNullableAll;}/// <summary>/// 构造函数,默认至少1个非空/// </summary>/// <param name="groupFields">属性名，多个属性名逗号隔开</param>public GroupEmptyAttribute(string groupFields){_groupFields = groupFields;_notNullableAll = false;}protected override ValidationResult IsValid(object value, ValidationContext validationContext){var validateResult = false;var obj = validationContext.ObjectInstance;Type Ts = obj.GetType();var fields = _groupFields.Split(',');if (fields.Count() > 0){for (var i = 0; i < fields.Count(); i++){var filedName = Convert.ToString(fields[i]);if (string.IsNullOrEmpty(filedName)) continue;//valuestring filedValue = Convert.ToString(Ts.GetProperty(filedName).GetValue(obj, null));//_notNullableAll=true，任意一个为空直接验证挂掉跳出循环if (_notNullableAll && string.IsNullOrWhiteSpace(filedValue)){validateResult = false;break;}//_notNullableAll=false,只要有一个不为空就可以过验证if (!_notNullableAll && !string.IsNullOrWhiteSpace(filedValue)){validateResult = true;break;}}}//successif (validateResult)return ValidationResult.Success;else{//failif (string.IsNullOrEmpty(ErrorMessage) && _notNullableAll)return new ValidationResult($"{_groupFields}字段全部不允许为空值");else if (string.IsNullOrEmpty(ErrorMessage) && !_notNullableAll)return new ValidationResult($"{_groupFields}字段中至少要有一个不为空的值");elsereturn new ValidationResult(ErrorMessage);}}}/// <summary>/// 组内数据同步判断，同时为空或同时不为空通过验证/// </summary>public class GroupEmptySyncAttribute : ValidationAttribute{private readonly string _groupFields;public GroupEmptySyncAttribute(string groupFields){_groupFields = groupFields;}protected override ValidationResult IsValid(object value, ValidationContext validationContext){var validateResult = true;var obj = validationContext.ObjectInstance;Type Ts = obj.GetType();var fields = _groupFields.Split(',');if (fields.Count() > 0){bool firstValueIsEmpty = true;//第一个值是否为空for (var i = 0; i < fields.Count(); i++){var filedName = Convert.ToString(fields[i]);if (string.IsNullOrEmpty(filedName)) continue;//valuestring filedValue = Convert.ToString(Ts.GetProperty(filedName).GetValue(obj, null));//第一个值记录是否为空if (i == 0 && string.IsNullOrWhiteSpace(filedValue))firstValueIsEmpty = true;if (i == 0 && !string.IsNullOrWhiteSpace(filedValue))firstValueIsEmpty = false;//后续值判断是否和第一个值符合，不符合直接结束验证if (i > 0){if (string.IsNullOrWhiteSpace(filedValue) != firstValueIsEmpty){validateResult = false;break;}}}}//successif (validateResult)return ValidationResult.Success;else{//failif (string.IsNullOrEmpty(ErrorMessage))return new ValidationResult($"{_groupFields}字段是否为空不一致（必须同时为空或同时不为空）");elsereturn new ValidationResult(ErrorMessage);}}}/// <summary>/// 判断时间格式是否对应，时间格式一致通过验证/// </summary>public class DateFormatValidAttribute : ValidationAttribute{private readonly string _formatStr;public DateFormatValidAttribute(string formatStr){_formatStr = formatStr;}protected override ValidationResult IsValid(object value, ValidationContext validationContext){var validateResult = false;try{//转成要求的格式后 再和传入的值对比var formatValue = Convert.ToDateTime((string)value).ToString(_formatStr);if ((string)value == formatValue)validateResult = true;elsevalidateResult = false;//successif (validateResult)return ValidationResult.Success;else{//failif (string.IsNullOrEmpty(ErrorMessage))return new ValidationResult($"时间格式不符合{_formatStr}格式");elsereturn new ValidationResult(ErrorMessage);}}catch (Exception ex){if (string.IsNullOrEmpty(ErrorMessage))return new ValidationResult($"时间格式不符合{_formatStr}格式");elsereturn new ValidationResult(ErrorMessage);}}}
}

使用：

测试结果：