ef-code-first - 一个或多个实体的验证失败。有关更多详细信息，请参见 'EntityValidationErrors'属性。代码优先

Question

我收到此错误:

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

当我尝试在Package Manager控制台中使用 Update-Database命令更新数据库时。

如何在Visual Studio中将行写入输出窗口？

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;
}

但这是行不通的。还有其他关于如何调试的建议吗？

Answer 1

我不知道为什么无法写入VS输出窗口以及如何使其工作。但是作为最后的选择，只需将错误写入文本文件，该文件应独立于您所拥有的应用程序的类型运行:

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()));

}