我正在尝试将洋葱模式与通用存储库 + 工作单元 + Entity Framework 5 + Ninject 与 Asp.net MVC4 一起使用，但我遇到了 EF“DetectChanges”功能的问题，我不明白为什么我需要将其设置为“假”。请你帮助我好吗？
我的解决方案是在 FindingBugContext.cs 文件的构造函数中添加以下行：
Configuration.AutoDetectChangesEnabled = false;
在以下代码的注释行中，我将更清楚地解释我的问题。这是一个非常简单（而且可能很愚蠢）的代码，它重现了我不理解的问题，并且我没有包含所有接口的代码，因为我认为弄清楚它非常简单。
这是我的服务类“RobotService.cs”：
public class RobotService : IRobotService
{
private readonly IRepository<Body> _repoBody;
private readonly IRepository<BodyPart> _repoBodyPart;
private readonly IRepository<Robot> _repoRobot;
private readonly IUnitOfWork _unitOfWork;
public RobotService(
IRepository<Body> repoBody,
IRepository<BodyPart> repoBodyPart,
IRepository<Robot> repoRobot,
IUnitOfWork unitOfWork)
{
_repoBody = repoBody;
_repoBodyPart = repoBodyPart;
_repoRobot = repoRobot;
_unitOfWork = unitOfWork;
}
public Robot Get(int id)
{
Robot robot = new Robot();
robot = _repoRobot.Get(id);
if (robot != null)
{
Body body = _repoBody.Get(robot.BodyId);
/* FROM NOW ON:
* robot.BodyId = 0 --> instead of 1: WHY???
* robot.Name = "Robby1"
*/
if (body != null)
{
BodyPart head = new BodyPart();
head = _repoBodyPart.Get(body.HeadId);
body.Head = head;
/* FROM NOW ON:
* body.BodyId = 0 --> instead of 1: WHY???
* body.HeadId = 0 --> instead of 1: WHY???
* body.LeftArmId = 0 --> instead of 2: WHY???
* body.RightArmId = 0 --> instead of 3: WHY???
* body.BodyName = "Body1" --> doesn't change
*/
BodyPart leftArm = new BodyPart();
leftArm = _repoBodyPart.Get(body.LeftArmId);
body.LeftArm = leftArm;
BodyPart rightArm = new BodyPart();
rightArm = _repoBodyPart.Get(body.RightArmId);
body.RightArm = rightArm;
robot.Body = body;
}
}
return robot;
}
这是我通过 NuGet 包“Ninject.MVC3”安装后在 NinjectWebCommon.cs 文件中的自定义代码：
private static void RegisterServices(IKernel kernel)
{
kernel.Bind(typeof(IRepository<>)).To(typeof(RepositoryBase<>)).InRequestScope();
kernel.Bind<IDbContextFactory>().To<DbContextFactory>().InRequestScope();
kernel.Bind<IUnitOfWork>().To<UnitOfWork>().InRequestScope();
kernel.Bind<IRobotService>().To<RobotService>();
}
这是我的 DbContext 类“FindingBugContext.cs”：
public class FindingBugContext : DbContext
{
public FindingBugContext()
: base("FindingBugContext")
{
//Configuration.AutoDetectChangesEnabled = false; //This is the solution
}
public virtual void Commit()
{
base.SaveChanges();
}
private IDbSet<Robot> _robots;
private IDbSet<Body> _bodies;
private IDbSet<BodyPart> _bodyParts;
public virtual IDbSet<T> DbSet<T>() where T : class
{
return Set<T>();
}
public IDbSet<Robot> Robots
{
get { return _robots ?? (_robots = DbSet<Robot>()); }
}
public IDbSet<Body> Bodies
{
get { return _bodies ?? (_bodies = DbSet<Body>()); }
}
public IDbSet<BodyPart> BodyParts
{
get { return _bodyParts ?? (_bodyParts = DbSet<BodyPart>()); }
}
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
Database.SetInitializer(new DropCreateFindingBugWithSeedData());
modelBuilder.Configurations.Add(new RobotConfiguration());
modelBuilder.Configurations.Add(new BodyConfiguration());
modelBuilder.Configurations.Add(new BodyPartConfiguration());
}
public class DropCreateFindingBugWithSeedData : DropCreateDatabaseAlways<FindingBugContext>
{
protected override void Seed(FindingBugContext context)
{
BodyPart head = new BodyPart() { Type = PartType.Head, PartName = "Head" };
BodyPart leftArm = new BodyPart() { Type = PartType.LeftArm, PartName = "LeftArm" };
BodyPart rightArm = new BodyPart() { Type = PartType.RightArm, PartName = "RightArm" };
Body body = new Body() { BodyName = "Body1", Head = head, HeadId = 1, LeftArm = leftArm, LeftArmId = 2, RightArm = rightArm, RightArmId = 3 };
Robot robot = new Robot() { Name = "Robby1", BodyId = 1, Body = body };
context.Robots.Add(robot);
}
}
public class RobotConfiguration : EntityTypeConfiguration<Robot>
{
public RobotConfiguration()
{
ToTable("Robots");
HasKey(r => r.RobotId)
.Property(r => r.RobotId)
.HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity);
HasRequired(r => r.Body)
.WithMany()
.HasForeignKey(r => r.BodyId);
}
}
public class BodyConfiguration : EntityTypeConfiguration<Body>
{
public BodyConfiguration()
{
ToTable("Bodies");
HasKey(b => b.BodyId)
.Property(b => b.BodyId)
.HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity);
HasRequired(b => b.Head)
.WithMany()
.HasForeignKey(b => b.HeadId)
.WillCascadeOnDelete(false);
HasRequired(b => b.LeftArm)
.WithMany()
.HasForeignKey(b => b.LeftArmId)
.WillCascadeOnDelete(false);
HasRequired(b => b.RightArm)
.WithMany()
.HasForeignKey(b => b.RightArmId)
.WillCascadeOnDelete(false);
}
}
public class BodyPartConfiguration : EntityTypeConfiguration<BodyPart>
{
public BodyPartConfiguration()
{
ToTable("BodyParts");
HasKey(b => b.BodyPartId)
.Property(b => b.BodyPartId)
.HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity);
}
}
}
这些是我的实体：
public class Robot
{
public Robot() { Body = new Body(); }
public int RobotId { get; set; }
public string Name { get; set; }
public int BodyId { get; set; }
public Body Body { get; set; }
}
公共类身体{公共身体（）{头=新的身体部分（）；LeftArm = new BodyPart(); RightArm = new BodyPart(); }
public int BodyId { get; set; }
public string BodyName { get; set; }
public int HeadId { get; set; }
public BodyPart Head { get; set; }
public int LeftArmId { get; set; }
public BodyPart LeftArm { get; set; }
public int RightArmId { get; set; }
public BodyPart RightArm { get; set; }
}
公共类 BodyPart { 公共 int BodyPartId { 获取；放; } 公共 PartType 类型 { 获取；放; } 公共字符串 PartName { 获取；放; } }
public enum PartType
{
Head,
LeftArm,
RightArm
}
这是工作单元代码：
public class UnitOfWork : IUnitOfWork
{
private readonly IDbContextFactory _dbContextFactory;
private FindingBugContext _context;
public UnitOfWork(IDbContextFactory dbContextFactory)
{
_dbContextFactory = dbContextFactory;
}
protected FindingBugContext FindingBugContext
{
get { return _context ?? (_context = _dbContextFactory.Get()); }
}
public void Commit()
{
FindingBugContext.Commit();
}
}
这是通用存储库代码：
public class RepositoryBase<T> : IRepository<T> where T : class
{
private FindingBugContext _context;
private readonly IDbSet<T> _dbSet;
public RepositoryBase(IDbContextFactory dbContextFactory)
{
DbContextFactory = dbContextFactory;
_dbSet = FindingBugContext.Set<T>();
}
public IDbContextFactory DbContextFactory
{
get;
private set;
}
public FindingBugContext FindingBugContext
{
get { return _context ?? (_context = DbContextFactory.Get()); }
}
//Read
public T Get(int id)
{
return _dbSet.Find(id);
}
}
这是我的 ContextFactory 代码：
public class DbContextFactory : Disposable, IDbContextFactory
{
private FindingBugContext _context;
public FindingBugContext Get()
{
if (_context == null)
{
_context = new FindingBugContext();
return _context;
}
else
{
return _context;
}
}
public void Dispose()
{
if (_context != null)
{
_context.Dispose();
}
}
}