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));
            }
        }