Entity Framework 在保存时抛出 Null 输入错误，C#

Question

我正在研究 Entity Framework 6 和存储库设置以执行 crud 操作。我正在尝试在 table 之一中插入记录，但即使不是 duo，也会出现空条目错误。

{"Cannot insert the value NULL into column 'UI_ID', table 'Blackpool_BPM.dbo.COURSE_INSTANCE'; column does not allow nulls. INSERT fails.\r\nThe statement has been terminated."}

数据库连接正确，我可以毫无问题地读取数据

在通用存储库中，在 Save() 之前正确获取数据

Table结构

Class 型号

 [Table("COURSE_INSTANCE")]
public class BIZCourseInstanceEntity
{
    [Key]
    public int UI_ID { get; set; }

    public string UnitInstanceCode { get; set; }

    public string FESLongDescription { get; set; }

    public string FESShortDescription { get; set; }

    public string FullDescription { get; set; }

    public string OwningOrganisationCode { get; set; }

    public int? OwningOrganisationID { get; set; }

    public string TopicCode { get; set; }

    public string UnitCategory { get; set; }

    public string UnitCode { get; set; }

    public string FESQualificationType { get; set; }

    public int? SCHOOLS { get; set; }

    public int? MARKETING_GROUPS { get; set; }
}

存储库

 public class BIZCourseInstanceRepository : GenericRepository<BIZCourseInstanceEntity>
{
    public BIZCourseInstanceRepository() { }

    public BIZCourseInstanceRepository(DbContext dbContext)
        :base(dbContext)
    { }
}

工作单元class

  public class BIZ_UOF : IDisposable
{
    private BIZDbContext _BIZDbContextObject = new BIZDbContext();

    protected BIZCourseInstanceRepository _BIZCourseInstanceRepository;

 public BIZCourseInstanceRepository BIZCourseInstanceRepository
    {
        get
        {
            if (this._BIZCourseInstanceRepository == null)
            {
                this._BIZCourseInstanceRepository = new BIZCourseInstanceRepository(_BIZDbContextObject);
            }

            return _BIZCourseInstanceRepository;
        }
    }
    /////

   public void Save()
    {
        _BIZDbContextObject.Database.Log = s => System.Diagnostics.Debug.WriteLine(s);

        _BIZDbContextObject.SaveChanges();
    }

    private bool disposed = false;

    protected virtual void Dispose(bool disposing)
    {
        if (!this.disposed)
        {
            if (disposing)
            {
                _BIZDbContextObject.Dispose();
            }
        }
        this.disposed = true;
    }

    public void Dispose()
    {
        Dispose(true);
        GC.SuppressFinalize(this);
    }

DbContext

public class BIZDbContext : BaseContext<BIZDbContext>
{
    public BIZDbContext() : base("_DbContext")
    { }

    public DbSet<BIZCourseInstanceEntity> BIZ_CourseInstance { get; set; }     
}

通用存储库 CRUD

 public void InsertEntity(TEntity obj)
    {
        _DbSet.Add(obj);
    }

函数 class 在 Save() 中生成错误

  public void InsertCourseInstance()
    {
        BIZCourseInstanceEntity BIZCourseInstanceEntityObject = null;

        BIZCourseInstanceEntityObject = new BIZCourseInstanceEntity
        {
            UI_ID = 999999,
            UnitInstanceCode = "KZ999999",
            FESLongDescription = "LONG",
            FESShortDescription = "SHORT",
            FullDescription = "FULL",
            OwningOrganisationCode = "E",
            OwningOrganisationID = 155,
            TopicCode = "04.1",
            UnitCategory = "04",
            UnitCode = "HE-G", 
            FESQualificationType = null,
            SCHOOLS = 5,
            MARKETING_GROUPS = 44

        };

        using (var _uow = new BIZ_UOF())
        {
            _uow.BIZCourseInstanceRepository.InsertEntity(BIZCourseInstanceEntityObject);

            _uow.Save();
        }
    }

Answer 1

您需要告诉Entity Framework您的 ID 是身份字段。如果它没有设置为数据库中的那个，那么你需要这样做。否则，您将需要查询下一个可用 ID，然后希望您不会与另一个试图同时保存内容的请求发生冲突。

[Table("COURSE_INSTANCE")]
public class BIZCourseInstanceEntity
{
    [Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int UI_ID { get; set; }
    ...
}

如果您绝对必须在没有任何类型的数据库生成主键选项的情况下工作，您可以改为使用枚举的 DatabaseGeneratedOption.None 值。应该避免这种情况，以防止您的 PK 发生冲突，但该选项确实存在。

Answer 2

我找到了答案，问题出在我的数据库中，我需要提供主键，在我的例子中是 UI_ID 但在我的模型中我没有定义 DatabaseGeneredOption.None，因此抛出错误，感谢 Krillgar 指导我

这是更新后的模型

[Table("COURSE_INSTANCE")]
public class BIZCourseInstanceEntity
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.None)]
    public int UI_ID { get; set; }

    [StringLength(255)]
    public string UnitInstanceCode { get; set; }

    [StringLength(255)]
    public string FESLongDescription { get; set; }

    [StringLength(255)]
    public string FESShortDescription { get; set; }

    [StringLength(255)]
    public string FullDescription { get; set; }

    [StringLength(255)]
    public string OwningOrganisationCode { get; set; }

    public int? OwningOrganisationID { get; set; }

    [StringLength(255)]
    public string TopicCode { get; set; }

    [StringLength(255)]
    public string UnitCategory { get; set; }

    [StringLength(255)]
    public string UnitCode { get; set; }

    [StringLength(50)]
    public string FESQualificationType { get; set; }

    public int? SCHOOLS { get; set; }

    public int? MARKETING_GROUPS { get; set; }
}

Entity Framework 在保存时抛出 Null 输入错误，C#

Entity Framework throwing Null entry error at Saving, C#

c#

entity-framework-6

repository-pattern

unit-of-work