EF代碼優先-System.InvalidOperationException

Question

我是EF Code First的新手，當我嘗試實現以下相同的錯誤時，

動作-在運行應用程序時：

1.在第一次遷移表之后，新記錄成功插入到“ GroupPrivileges”上。

2.更新“ GroupPrivileges”的相同記錄時，將引發錯誤。

3.類似地，當我嘗試在“ GroupPrivileges”上插入新的第二條記錄時，會彈出相同的錯誤。

錯誤：

EntityFramework.dll中發生類型'System.InvalidOperationException'的異常，但未在用戶代碼中處理

附加信息：不能設置類型為'System.Collections.Generic.List`1 [[Dsms.Model.User.GroupModel，Dsms.Model，Version = 1.0.0.0，Culture = neutral，PublicKeyToken = null]]'的對象或從類型為'Dsms.Model.User.GroupModel'的EntityReference的Value屬性中刪除。

請幫助我解決此問題，我無法采取進一步措施:-(

有了這個，請找到下面的模型和DBConfig類。

public abstract class BaseModel
{
    public int DrivingSchoolId { get; set; }
    public int UserId { get; set; }
    public string ExternalId { get; set; }
    [Display(Name = "Active")]
    public bool IsActive { get; set; }
    public int CreatedBy { get; set; }
    public DateTime CreatedOn { get; set; }
    public int ModifiedBy { get; set; }
    public DateTime ModifiedOn { get; set; }

    public BaseModel()
    {
        IsActive = true;
        CreatedOn = DateTime.Now;
        ModifiedOn = DateTime.Now;
        ExternalId = Guid.NewGuid().ToString("N");    
    }
}

public class GroupModel : BaseModel
{
    [Key]
    public int GroupId { get; set; }

    [Display(Name = "Name")]
    [DataType(DataType.Text)]
    [Required(ErrorMessage = "Please fill the 'Name'")]
    [MaxLength(100, ErrorMessage = "Maximum character lenght of 'Name' is 100.")]
    public string Name { get; set; }

    [Display(Name = "Code")]
    [DataType(DataType.Text)]
    [Required(ErrorMessage = "Please fill the 'Code'")]
    [MaxLength(15, ErrorMessage = "Maximum character lenght of 'Code' is 15.")]
    public string Code { get; set; }

    [Display(Name = "Description")]
    [DataType(DataType.MultilineText)]
    [MaxLength(500, ErrorMessage = "Maximum character lenght of 'Description' is 500.")]
    public string Description { get; set; }

    //EF Navigation properties starts
    public virtual ICollection<DrivingSchoolModel> DrivingSchools { get; set; }
    public virtual UserGroupModel UserGroup { get; set; }
    public virtual GroupPrivilegeModel GroupPrivilege { get; set; }
}

public class RoleModel : BaseModel
{
    [Key]
    public int RoleId { get; set; }

    [Display(Name = "Name")]
    [DataType(DataType.Text)]
    [Required(ErrorMessage = "Please fill the 'Name'")]
    [MaxLength(100, ErrorMessage = "Maximum character lenght of 'Name' is 100.")]
    public string Name { get; set; }

    [Display(Name = "Code")]
    [DataType(DataType.Text)]
    [Required(ErrorMessage = "Please fill the 'Code'")]
    [MaxLength(15, ErrorMessage = "Maximum character lenght of 'Code' is 15.")]
    public string Code { get; set; }

    [Display(Name = "Description")]
    [DataType(DataType.MultilineText)]
    [MaxLength(500, ErrorMessage = "Maximum character lenght of 'Description' is 500.")]
    public string Description { get; set; }

    //EF Navigation properties starts
    public virtual GroupPrivilegeModel GroupPrivilege { get; set; }
    public virtual UserRoleModel UserRole { get; set; }        
}

public class GroupPrivilegeModel : BaseModel
{
    [Key]
    public int GroupPrivilegeId { get; set; }

    [Display(Name = "Group")]
    [DataType(DataType.Text)]
    [Required(ErrorMessage = "Please select the 'Group'")]
    public int GroupId { get; set; }

    [Display(Name = "Role")]
    [DataType(DataType.Text)]
    [Required(ErrorMessage = "Please select the 'Role'")]
    public int RoleId { get; set; }

    //EF Navigation properties starts
    public virtual ICollection<GroupModel> Groups { get; set; }
    public virtual ICollection<RoleModel> Roles { get; set; }
}

    public GroupConfiguration()
    {
        this.ToTable("Groups", DsmsContext.DEFAULT_DB_SCHEMA);

        this.HasKey(g => g.GroupId);

        this.HasRequired(g => g.DrivingSchools).WithMany().HasForeignKey(g => g.DrivingSchoolId);

        this.Property(g => g.ExternalId).HasColumnName("ExternalGroupId").HasMaxLength(50).IsRequired();
        this.Property(g => g.Name).HasMaxLength(100).IsRequired();
        this.Property(g => g.Code).HasMaxLength(15).IsRequired();
        this.Property(g => g.Description).HasMaxLength(500).IsOptional();
        this.Property(g => g.DrivingSchoolId).IsRequired();
        this.Property(g => g.IsActive).IsRequired();
        this.Property(g => g.CreatedBy).IsRequired();
        this.Property(g => g.CreatedOn).IsRequired();
        this.Property(g => g.ModifiedBy).IsOptional();
        this.Property(g => g.ModifiedOn).IsOptional();

        this.Ignore(g => g.UserId);
        this.Ignore(g => g.UserGroup);
        this.Ignore(g => g.GroupPrivilege);
    }

    public RoleConfiguration()
    {
        this.ToTable("Roles", DsmsContext.DEFAULT_DB_SCHEMA);

        this.HasKey(r => r.RoleId);

        this.Property(r => r.ExternalId).HasColumnName("ExternalRoleId").HasMaxLength(50).IsRequired();
        this.Property(r => r.Name).HasMaxLength(100).IsRequired();
        this.Property(r => r.Code).HasMaxLength(15).IsRequired();
        this.Property(r => r.Description).HasMaxLength(500).IsOptional();
        this.Property(r => r.IsActive).IsRequired();
        this.Property(r => r.CreatedBy).IsRequired();
        this.Property(r => r.CreatedOn).IsRequired();
        this.Property(r => r.ModifiedBy).IsOptional();
        this.Property(r => r.ModifiedOn).IsOptional();

        this.Ignore(r => r.DrivingSchoolId);
        this.Ignore(r => r.UserId);
        this.Ignore(r => r.GroupPrivilege);
        this.Ignore(r => r.UserRole);
    }

    public GroupPrivilegeConfiguration()
    {
        this.ToTable("GroupPrivileges", DsmsContext.DEFAULT_DB_SCHEMA);

        this.HasKey(gp => gp.GroupPrivilegeId);

        this.HasRequired(gp => gp.Groups).WithMany().HasForeignKey(gp => gp.GroupId);
        this.HasRequired(gp => gp.Roles).WithMany().HasForeignKey(gp => gp.RoleId);

        this.Property(gp => gp.IsActive).IsRequired();
        this.Property(gp => gp.CreatedBy).IsRequired();
        this.Property(gp => gp.CreatedOn).IsRequired();
        this.Property(gp => gp.ModifiedBy).IsOptional();
        this.Property(gp => gp.ModifiedOn).IsOptional();

        this.Ignore(gp => gp.DrivingSchoolId);
        this.Ignore(gp => gp.UserId);
        this.Ignore(gp => gp.ExternalId);
    }

Answer 1

在您的更新方法中，如果您擺脫了existingRecord變量，而只需執行以下操作，那就更好了：

_contex.Entry(model).State = System.Data.Entity.EntityState.Modified;
_context.SaveChages();

與Insert方法相同：

 _context.GroupePrivilages.Add(model);
 _context.SaveChages();

也：

• 確保在GroupPrivilageModel內引用的對象不為null，並且還具有所有必填字段。
• 您必須告訴EF將您的一個映射到模型中的多個關系。 這里有一個很好的解釋： MVC5 EF實體顯然正在保存，但是在檢索時為null