通用存储库、工作单元、Unity的体系结构问题

Question

我正在使用MVC5、EntityFramework、Unity、UnitOfWork和Generic Repository开发我的一个项目架构，我也没有使用AutoMapper或任何类似于AutoMapper的东西。

每当我第一次执行更新时，它都能完美地工作，但第二次以后，它会给我以下错误。

附加类型为"EntityModel.tblCompanyMaster"的实体失败，因为同一类型的另一个实体已具有相同的主键值。如果图中的任何实体具有冲突的键值，则使用"Attach"方法或将实体的状态设置为"Unchanged"或"Modified"时可能会发生这种情况。这可能是因为一些实体是新的，并且尚未接收到数据库生成的键值。在这种情况下，请使用"Add"方法或"Added"实体状态来跟踪图形，然后根据情况将非新实体的状态设置为"Unchanged"或"Modified"。

此处的更新方法出现错误[_dbSet.Attach(entity)]

public virtual void UpdateEntity(TEntity entity, string[] NoUpdateProperty = null)
{
_dbSet.Attach(entity);
_dbContext.Entry<TEntity>(entity).State = EntityState.Modified;
.
.
}

这是我的代码：

1) Unity

public static class UnityConfig
{
public static void RegisterComponents()
{
var container = new UnityContainer();
//container.RegisterType<DbContext, dbTestCMSEntities>();
container.RegisterSingleton<IUnitOfWork, UnitOfWork>();
container.RegisterSingleton(typeof(IDbHelper<>), typeof(DbHelper<>));            
container.RegisterSingleton<ICompanyMasterBL, tblCompanyMasterBL>();            
DependencyResolver.SetResolver(new UnityDependencyResolver(container));
}
}

2) 工作单位

public interface IUnitOfWork
{
dbTestCMSEntities dbContext { get; }
void Save();
}
public class UnitOfWork : IUnitOfWork, IDisposable
{
public dbTestCMSEntities dbContext { get; }
private bool _disposed = false;
public UnitOfWork(dbTestCMSEntities context)
{
dbContext = context;
}
public void Save()
{
try
{
dbContext.SaveChanges();
}
catch (Exception ex)
{
throw ex;
}
}
protected virtual void Dispose(bool disposing)
{
if (!this._disposed)
{
if (disposing)
{
dbContext.Dispose();
}
}
this._disposed = true;
}
public void Dispose()
{
Dispose(true);
GC.SuppressFinalize(this);
}
}

3) 通用存储库

public interface IDbHelper<TEntity> where TEntity : class
{
bool Exists(object pkId);
TEntity GetFirst(Expression<Func<TEntity, bool>> condition, Expression<Func<TEntity, dynamic>> order = null);
IEnumerable<TEntity> GetMany(Expression<Func<TEntity, bool>> condition, Expression<Func<TEntity, string>> order = null);
IEnumerable<TEntity> GetPagedList(Expression<Func<TEntity, bool>> condition, Expression<Func<TEntity, Int64>> _order, int currentPageIndex, out int Total);
void InsertEntity(TEntity entity);
void InsertEntity(List<TEntity> entity);
void UpdateEntity(TEntity entity, string[] NoUpdateProperty = null);
void UpdateEntity(List<TEntity> entity, string[] NoUpdateProperty = null);
void Delete(object id);
void Delete(TEntity entity);
void DeleteEntity(Expression<Func<TEntity, bool>> condition);
}
public class DbHelper<TEntity> : IDbHelper<TEntity> where TEntity : class
{
protected readonly dbTestCMSEntities _dbContext;
protected DbSet<TEntity> _dbSet;
public DbHelper(IUnitOfWork unitOfWork)
{
_dbContext = unitOfWork.dbContext;
_dbSet = _dbContext.Set<TEntity>();
}
public bool Exists(object pkId)
{
return _dbSet.Find(pkId) != null;
}
public TEntity GetFirst(Expression<Func<TEntity, bool>> condition, Expression<Func<TEntity, dynamic>> order = null)
{
IQueryable<TEntity> lstResult = _dbSet.AsNoTracking().AsQueryable();
if (order != null)
lstResult = lstResult.AsNoTracking().OrderBy(order).AsQueryable();
if (condition != null)
lstResult = lstResult.AsNoTracking().Where(condition).AsQueryable();
TEntity entity = lstResult.AsNoTracking().FirstOrDefault();
return entity;
}
public virtual IEnumerable<TEntity> GetMany(Expression<Func<TEntity, bool>> condition, Expression<Func<TEntity, string>> order = null)
{
IQueryable<TEntity> lstResult = _dbSet.AsNoTracking().AsQueryable();
if (condition != null)
lstResult = lstResult.AsNoTracking().Where(condition).AsQueryable();
if (order != null)
lstResult = lstResult.AsNoTracking().OrderBy(order).AsQueryable();
return lstResult;
}
public virtual IEnumerable<TEntity> GetPagedList(Expression<Func<TEntity, bool>> condition, Expression<Func<TEntity, Int64>> _order, int currentPageIndex, out int Total)
{
IQueryable<TEntity> lstResult = _dbSet.AsNoTracking().AsQueryable();
if (condition != null)
lstResult = lstResult.AsNoTracking().Where(condition).AsQueryable();
Total = lstResult.Count();
lstResult = lstResult.AsNoTracking().OrderByDescending(_order).AsQueryable().Skip((currentPageIndex - 1) * StringUtility.ItemsPerPage).Take(StringUtility.ItemsPerPage);
return lstResult;
}
/// <summary>
/// Insert single record
/// </summary>
/// <param name="entity"></param>
public virtual void InsertEntity(TEntity entity)
{
_dbSet.Add(entity);
}
/// <summary>
/// Insert multiple records
/// </summary>
/// <param name="entity"></param>
public virtual void InsertEntity(List<TEntity> entity)
{
_dbSet.AddRange(entity);
}
/// <summary>
/// Update single entity
/// </summary>
/// <param name="entity"></param>
/// <param name="NoUpdateProperty"></param>
public virtual void UpdateEntity(TEntity entity, string[] NoUpdateProperty = null)
{
_dbSet.Attach(entity);
_dbContext.Entry<TEntity>(entity).State = EntityState.Modified;
if (NoUpdateProperty != null)
{
foreach (string item in NoUpdateProperty)
{
_dbContext.Entry<TEntity>(entity).Property(item).IsModified = false;
}
}
}
/// <summary>
/// Update multiple entity
/// </summary>
/// <param name="entity"></param>
/// <param name="NoUpdateProperty"></param>
public virtual void UpdateEntity(List<TEntity> entity, string[] NoUpdateProperty = null)
{
foreach (TEntity item in entity)
{
_dbSet.Attach(item);
_dbContext.Entry<TEntity>(item).State = EntityState.Modified;
if (NoUpdateProperty != null)
{
foreach (string item1 in NoUpdateProperty)
{
_dbContext.Entry<TEntity>(item).Property(item1).IsModified = false;
}
}
}
}
/// <summary>
/// Generic Delete method for the entities. Delete one record only.
/// </summary>
/// <param name="id"></param>
public virtual void Delete(object id)
{
TEntity entityToDelete = _dbSet.Find(id);
Delete(entityToDelete);
}
/// <summary>
/// Generic Delete method for the entities. Delete one record only.
/// </summary>
/// <param name="entityToDelete"></param>
public virtual void Delete(TEntity entity)
{
if (_dbContext.Entry(entity).State == EntityState.Detached)
{
_dbSet.Attach(entity);
}
_dbSet.Remove(entity);
}
/// <summary>
/// Delete one or many records based on given condition
/// </summary>
/// <param name="condition"></param>
public void DeleteEntity(Expression<Func<TEntity, bool>> condition)
{
_dbSet.RemoveRange(_dbSet.Where(condition));
}
}

我尝试了很多方法，但都无济于事，我相信我在Unity&工作单位，但很难确定。提前谢谢你帮我。

Answer 1

每当我第一次执行更新时，它都能完美地工作，但第二次以后，它会给我以下错误。

可能您正试图为多个请求重用DbContext实例。您的DI容器似乎正在将事物注册为singleton。DbContext的作用域应为每个请求。

Answer 2

下面的代码帮助我找到解决方案，只需在Attach()之前调用此方法即可，同时更新：

public Boolean Exists(T entity) {
var objContext = ((IObjectContextAdapter)this._dbContext).ObjectContext;
var objSet = objContext.CreateObjectSet<T>();
var entityKey = objContext.CreateEntityKey(objSet.EntitySet.Name, entity);
Object foundEntity;
var exists = objContext.TryGetObjectByKey(entityKey, out foundEntity);
if (exists) {
objContext.Detach(foundEntity);
}
return (exists);
}