验证失败的一个或多个实体。 见“EntityValidationErrors”了解详情财产。

我得到这个错误：

Validation failed for one or more entities. See 'EntityValidationErrors' property for more details.

当我尝试更新与数据库Update-Database在Package Manager控制台命令。

我怎么能写行Visual Studio中的输出窗口？

我试过了：

try
{
    context.SaveChanges();
}
catch (System.Data.Entity.Validation.DbEntityValidationException e)
{
    foreach (var eve in e.EntityValidationErrors)
    {
        System.Diagnostics.Debug.WriteLine("Entity of type \"{0}\" in state \"{1}\" has the following validation errors:",
            eve.Entry.Entity.GetType().Name, eve.Entry.State);
        foreach (var ve in eve.ValidationErrors)
        {
            System.Diagnostics.Debug.WriteLine("- Property: \"{0}\", Error: \"{1}\"",
                ve.PropertyName, ve.ErrorMessage);
        }
    }
    throw;
}

但是，这并不能正常工作。 对任何其他建议如何调试呢？

Answer 1:

我不知道为什么写VS输出窗口没有工作和如何使它发挥作用。 但是，作为最后的手段只写错误到一个文本文件，它应该独立工作，你有应用程序的类型：

try
{
    context.SaveChanges();
}
catch (System.Data.Entity.Validation.DbEntityValidationException e)
{
    var outputLines = new List<string>();
    foreach (var eve in e.EntityValidationErrors)
    {
        outputLines.Add(string.Format(
            "{0}: Entity of type \"{1}\" in state \"{2}\" has the following validation errors:",
            DateTime.Now, eve.Entry.Entity.GetType().Name, eve.Entry.State));
        foreach (var ve in eve.ValidationErrors)
        {
            outputLines.Add(string.Format(
                "- Property: \"{0}\", Error: \"{1}\"",
                ve.PropertyName, ve.ErrorMessage));
        }
    }
    //Write to file
    System.IO.File.AppendAllLines(@"c:\temp\errors.txt", outputLines);
    throw;

    // Showing it on screen
    throw new Exception( string.Join(",", outputLines.ToArray()));

}

Answer 2:

你可以通过它的异常堆栈像下面。

try
{
    _dbContext.SaveChanges();
}
catch (DbEntityValidationException dbValEx)
{
   var outputLines = new StringBuilder();
   foreach (var eve in dbValEx.EntityValidationErrors)
   {
     outputLines.AppendFormat("{0}: Entity of type \"{1}\" in state \"{2}\" has the following validation errors:"
       ,DateTime.Now, eve.Entry.Entity.GetType().Name, eve.Entry.State);

     foreach (var ve in eve.ValidationErrors)
     {
       outputLines.AppendFormat("- Property: \"{0}\", Error: \"{1}\""
        ,ve.PropertyName, ve.ErrorMessage);
     }
   }

 throw new DbEntityValidationException(string.Format("Validation errors\r\n{0}"
  ,outputLines.ToString()), dbValEx);
}

文章来源: Validation failed for one or more entities. See 'EntityValidationErrors' property for more details. Code First