WebApi數據驗證——ModelState驗證返回全部錯誤信息，並統一返回公共結果類，

一. 公共返回類（根據項目須要來定義，與正常請求數據返回結果類一致）

注：泛型的返回類請本身擴充，本文只爲示例，只列舉一個非泛型的返回類。

     EnumAppCode 爲錯誤碼的枚舉，請自行定義。

using OF.Utility;

namespace Certification.Api.Common
{
    /// <summary>
    /// 統一返回結果,用於不須要返回具體結果實體的方法調用中，即只包含status和message兩個屬性,請不要擅自修改改類的任何地方 
    /// </summary>
    public class ResultData
    {
        private ResultData()
        {
            
        }
        /// <summary>
        /// 返回狀態
        /// 0：成功,不然失敗
        /// </summary>
        public int status { set; get; }
      
        /// <summary>
        /// 錯誤信息
        /// </summary>
        public string message { set; get; }

        

       
        /// <summary>
        /// 
        /// </summary>
        /// <returns></returns>
        public static ResultData Success()
        {
            ResultData result = new ResultData
            {
                status = 0,
                message = "",
            };
            return result;
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="msg"></param>
        /// <returns></returns>
        public static ResultData Success(string msg)
        {
            ResultData result = new ResultData
            {
                status = 0,
                message = msg,
            };
            return result;
        }

        public static ResultData Error()
        {
           return Error(EnumAppCode.RequestError);
        }
        /// <summary>
        /// 
        /// </summary>
        /// <param name="errorCode"></param>
        /// <returns></returns>
        public static ResultData Error(EnumAppCode errorCode)
        {
            ResultData result = new ResultData
            {
                status = (int)errorCode,
                message = errorCode.GetEnumText()
            };
            return result;
        }
        /// <summary>
        /// 
        /// </summary>
        /// <param name="errorCode"></param>
        /// <param name="errMsg"></param>
        /// <returns></returns>
        public static ResultData Error(EnumAppCode errorCode,string errMsg)
        {
            ResultData result = new ResultData
            {
                status = (int)errorCode,
                message = errMsg
            };
            return result;
        }
    }

    

}

二. 編寫ModelState擴展方法，拼接ModelState錯誤信息

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web.Http.ModelBinding;

namespace Certification.Api.Common
{
    /// <summary>
    /// ModelState擴展類
    /// </summary>
    public static class ModelStateExtension
    {
        /// <summary>
        /// 獲取模型綁定中的第一條錯誤信息
        /// </summary>
        /// <param name="msDictionary"></param>
        /// <returns></returns>
        public static string GetFirstErrMsg(this ModelStateDictionary msDictionary)
        {
            if (msDictionary.IsValid || !msDictionary.Any()) return "";
            foreach (string key in msDictionary.Keys)
            {
                ModelState tempModelState = msDictionary[key];
                if (tempModelState.Errors.Any())
                {
                    var firstOrDefault = tempModelState.Errors.FirstOrDefault();
                    if (firstOrDefault != null)
                        return firstOrDefault.ErrorMessage;
                }
            }
            return "";
        }
        /// <summary>
        ///  獲取錯誤信息列表
        /// </summary>
        /// <param name="msDictionary"></param>
        /// <returns></returns>
        public static List<string> GetErrMsgList(this ModelStateDictionary msDictionary)
        {
            var list = new List<string>();
            if (msDictionary.IsValid || !msDictionary.Any()) return list;

            //獲取全部錯誤的Key
            foreach (string key in msDictionary.Keys)
            {
                ModelState tempModelState = msDictionary[key];
                if (tempModelState.Errors.Any())
                {
                    var errorList = tempModelState.Errors.ToList();
                    foreach (var item in errorList)
                    {
                        list.Add(item.ErrorMessage);
                    }
                }
            }
            return list;
        }

        /// <summary>
        /// 獲取ModelState全部錯誤信息，間隔符間隔
        /// </summary>
        /// <param name="splitStr">間隔符</param>
        /// <returns></returns>
        public static string GetAllErrMsgStr(this ModelStateDictionary msDictionary, string splitStr)
        {
            var returnStr = "";
            if (msDictionary.IsValid || !msDictionary.Any()) return returnStr;

            //獲取全部錯誤的Key
            foreach (string key in msDictionary.Keys)
            {
                ModelState tempModelState = msDictionary[key];
                if (tempModelState.Errors.Any())
                {
                    var errorList = tempModelState.Errors.ToList();
                    foreach (var item in errorList)
                    {
                        returnStr += item.ErrorMessage + splitStr;
                    }
                }
            }
            return returnStr;
        }
    }
}

三. 編寫Filter過濾器，添加WebApi全局驗證

能夠配合上篇文章《WebApi數據驗證——編寫自定義數據註解（Data Annotations）》使用，

利用自定義註解定義驗證規則和錯誤信息，API項目Filter全局統一攔截驗證拋出自定義的錯誤信息。

using Certification.Api.Common;
using Newtonsoft.Json;
using System.Net.Http;
using System.Text;
using System.Web.Http.Controllers;
using System.Web.Http.Filters;

namespace Certification.Api.Filters
{
    public class GlobalActionFilterAttribute : ActionFilterAttribute
    {
        public override void OnActionExecuting(HttpActionContext actionContext)
        {
            if (actionContext.ModelState.IsValid == false)
            {
                var result = ResultData.Error(EnumAppCode.InternalServer);
                result.message = actionContext.ModelState.GetAllErrMsgStr(",");
                actionContext.Response = new HttpResponseMessage { Content = new StringContent(JsonConvert.SerializeObject(result), Encoding.GetEncoding("UTF-8"), "application/json") };
            }
        }
    }

}