C# ASP.NET MVC:空外键ID导致验证错误

短篇小说：

我从db加载一个模型实例，对其应用更改，但当我想更新更改时，在模型定义中设置为

[必需]

的外键项会发生验证异常。我已经找到了解决办法，但我不知道什么是解决这个问题的正确方法

详细信息：

我有一个模型如下：

public class Project
{
    public int Id { get; set; }

    [Required]
    [StringLength(100, MinimumLength = 5]
    public string Name { get; set; }

    [Required]
    public virtual ApplicationUser Client { get; set; }

    [Key]
    [ForeignKey("Client")]
    public string ClientID;


    [Required]
    public virtual ApplicationUser ProjectManager { get; set; }

    [Key]
    [ForeignKey("ProjectManager")]
    public string ProjectManagerID;

    [Range(0,100)]
    [Required]
    public int Progress { get; set; }

    [DataType(DataType.Date)]
    [DisplayFormat(DataFormatString = "{0:yyyy-MM-dd}", ApplyFormatInEditMode = true)]
    public DateTime CreateDate { get; set; }

    [Column("Disabled")]
    public bool Disabled{ get; set; }

    [Column("Status")]
    public string Status{ get; set; }



}

    public DbSet<Project> Projects { get; set; }

每当我从db中获取模型信息并对其应用更改时，我都会遇到异常，这些异常是必需的

ProjectManager

和

Client

Project currentProject = (from prj in dbContext.Projects
                                      where prj.Id == project.Id).Single();
//---> currentProject.ProjectManagerID      is  null 
//---> currentProject.ClientID              is  null 
//---> currentProject.ProjectManager        is  present
//---> currentProject.Client                is  present

currentProject.Name = ....
currentProject.Progress = ....
currentProject.Status = ....
currentProject.Disabled = ....
dbContext.Entry(currentProject).State = System.Data.Entity.EntityState.Modified;
dbContext.SaveChanges();        //--> Validation error for required Client,ProjectManager

这是因为当我从DB、ClientID和ProjectManagerID中获取信息时为空，并且如果我按以下方式手动设置它们，它将修复：

            currentProject.Name = project.Name;
            currentProject.Progress = project.Progress;
            currentProject.Status = project.Status;
            currentProject.Disabled = project.Disabled;
            currentProject.ProjectManagerID = currentProject.ProjectManager.Id;
            currentProject.ClientID = currentProject.Client.Id;
            try
            {
                dbContext.Entry(currentProject).State = System.Data.Entity.EntityState.Modified;
                dbContext.SaveChanges();
            }
            catch (DbEntityValidationException e)
            {
                addValidationErrorsToModelState(e);
                return View(project);
            }

我怀疑

virtual

设置，但不确定，因为加载了外来对象，但其ID为空

p.S.I在AppDbContext中宣布的项目如下：

public class Project
{
    public int Id { get; set; }

    [Required]
    [StringLength(100, MinimumLength = 5]
    public string Name { get; set; }

    [Required]
    public virtual ApplicationUser Client { get; set; }

    [Key]
    [ForeignKey("Client")]
    public string ClientID;


    [Required]
    public virtual ApplicationUser ProjectManager { get; set; }

    [Key]
    [ForeignKey("ProjectManager")]
    public string ProjectManagerID;

    [Range(0,100)]
    [Required]
    public int Progress { get; set; }

    [DataType(DataType.Date)]
    [DisplayFormat(DataFormatString = "{0:yyyy-MM-dd}", ApplyFormatInEditMode = true)]
    public DateTime CreateDate { get; set; }

    [Column("Disabled")]
    public bool Disabled{ get; set; }

    [Column("Status")]
    public string Status{ get; set; }



}

    public DbSet<Project> Projects { get; set; }

公共数据库集项目{get；set；}

问题是我错过了foreignkey的ID属性的setter/getter：

public class Project
{
    public int Id { get; set; }

    [Required]
    [StringLength(100, MinimumLength = 5]
    public string Name { get; set; }

    [Required]
    public virtual ApplicationUser Client { get; set; }


    [ForeignKey("Client")]
    public string ClientID{ get; set; } //<--fixed 


    [Required]
    public virtual ApplicationUser ProjectManager { get; set; }


    [ForeignKey("ProjectManager")]
    public string ProjectManagerID { get; set; } //<--fixed 

    [Range(0,100)]
    [Required]
    public int Progress { get; set; }

    [DataType(DataType.Date)]
    [DisplayFormat(DataFormatString = "{0:yyyy-MM-dd}", ApplyFormatInEditMode = true)]
    public DateTime CreateDate { get; set; }

    [Column("Disabled")]
    public bool Disabled{ get; set; }

    [Column("Status")]
    public string Status{ get; set; }

}

公共类项目
{
公共int Id{get；set；}
[必需]
[StringLength（100，最小长度=5]
公共字符串名称{get；set；}
[必需]
公共虚拟应用程序用户客户端{get；set；}
[外国钥匙（“客户”）]
公共字符串ClientID{get；set；}//