Question

 [Table("Employee", Schema = "Master")]
public class Employee : Common
{
    #region Properties

    [Required]
    [Key]
    public int EmployeeID { get; set; }


    public virtual Department Department { get; set; }
    public int? DepartmentId { get; set; }


    #endregion
}


[Table("Department", Schema = "Lookup")]
public class Department : Common
{
    [Required]
    [Key]
    public int DepartmentId { get; set; }
    [Required]
    [StringLength(50)]
    public string Value { get; set; }
    public string Description { get; set; }
    public virtual ICollection<Employee> Employees { get; set; }
}

获取数据 var employee = CemexDb.Employee.Where（w =＆gt; w.EmployeeID == employeeId）.FirstOrDefault（）;

当我获取数据时，部门总是为空

请建议解决方法

这是我的代码上下文类

中的上下文类

   public class CemexDb : DbContext
{

    public virtual IDbSet<T> DbSet<T>() where T : class
    {
        return Set<T>();
    }
    public CemexDb() : base(ConfigurationManager.ConnectionStrings["CemexDb"].ConnectionString)
    {
        this.Configuration.LazyLoadingEnabled = true;
        this.Configuration.ProxyCreationEnabled = true;
    } 

    public CemexDb(string connectionString): base(connectionString)
    {
        this.Configuration.LazyLoadingEnabled = true;
        this.Configuration.ProxyCreationEnabled = true;
    }


    public virtual void Commit()
    {
        base.SaveChanges();
    }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        base.OnModelCreating(modelBuilder);
        Database.SetInitializer<CemexDb>(null);
    }

}

这是访问代码

 public class EmployeeService : RepositoryBase, IEmployeeService
{
    public EmployeeService(IDatabaseFactory DbFactory): base(DbFactory)
    { }

}

存储库基类

    public abstract class RepositoryBase 
{
    private CemexDb db;

    /// <summary>
    /// Holds a reference to the DatabaseFactory class used to manage connections to the database.
    /// </summary>
    protected IDatabaseFactory DatabaseFactory { get; private set; }
    /// <summary>
    /// Contains a reference to the <see cref="System.Data.Entity.DbContext"/> instance used by the repository.
    /// </summary>
    protected CemexDb CemexDb { get { return db ?? (db = DatabaseFactory.Get()); } }

    /// <summary>
    /// Initialises a new instance of the RepositoryBase class.
    /// </summary>
    /// <param name="DbFactory">A valid DatabaseFactory <see cref="Opendesk.Data.DatabaseFactory"/> object.</param>
    public RepositoryBase(IDatabaseFactory DbFactory)
    {
        DatabaseFactory = DbFactory;
    }

}

Answer 1

您必须启用代理生成，并将集合属性定义为虚拟，以便延迟加载工作。上下文也应该保持活力。

  public class CemexDb : DbContext
  {
     public CemexDb()
     {
        this.Configuration.ProxyCreationEnabled = true;
     } 

     public DbSet<Unicorn> Employees { get; set; }

  }

延迟加载在Code First中不起作用

1 个答案: