获取EntityFrameWork返回的错误和ModelState中的错误

都是通过循环才能找到具体的错误信息

具体方法参见这两篇文章：

EntityFrameWork:

http://www.cnblogs.com/shouzheng/archive/2012/04/19/2456817.html

关键部分

 string error = string.Empty;
 using (var blog = new Blog())
 {
     Author author = new Author
     {
         Name = "ErrorNameForTest"
     };
     blog.Authors.Add(author);
 
     try
     {
         blog.SaveChanges();
     }
     catch (DbEntityValidationException ex)
     {
         foreach (var item in ex.EntityValidationErrors)
         {
         foreach (var item2 in item.ValidationErrors)
         {
             error = string.Format("{0}:{1}\r\n", item2.PropertyName, item2.ErrorMessage);
         }
         }
     }
 }
 return error;

另一篇获取ModelState中的错误：

http://www.cnblogs.com/bjs007/archive/2010/12/08/1900734.html

 代码
 [HttpPost]
         public ActionResult CreateComment(Comment comment)
         {
             if (!ModelState.IsValid)
             {
                 List<string> sb = new List<string>();
                 //获取所有错误的Key
                 List<string> Keys = ModelState.Keys.ToList();
                 //获取每一个key对应的ModelStateDictionary
                 foreach (var key in Keys)
                 {
                     var errors = ModelState[key].Errors.ToList();
                     //将错误描述添加到sb中
                     foreach (var error in errors)
                     {
                         sb.Add(error.ErrorMessage);
                     }
                 }
                 return Json(sb);
             }
             else
             {
                 return Json(commentRepository.InsertComment(comment));
             }
         }