通用存储库、工作单元、Unity 的架构问题

Question

我正在使用 MVC5、EntityFramework、Unity、UnitOfWork 和 Generic Repository 开发我的项目架构之一，而且我还没有使用 AutoMapper 或任何其他类似于 AutoMapper 的东西。

每当我第一次执行更新时，它都能完美运行，但第二次之后，它会出现以下错误。

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经具有相同的主键值。如果图中的任何实体具有冲突的键值，则在使用“附加”方法或将实体的状态设置为“未更改”或“已修改”时，可能会发生这种情况。这可能是因为某些实体是新实体，尚未收到数据库生成的键值。在这种情况下，使用“添加”方法或“已添加”实体状态来跟踪图形，然后根据需要将非新实体的状态设置为“未更改”或“已修改”。

此处更新方法发生错误 [_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) 团结

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) 工作单元

    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，但没有帮助我，我相信我在 Unity 和 Unit Of Work 上做错了，但很难识别。提前感谢您帮助我。

Answer 1

每当我第一次执行更新时，它都能完美运行，但第二次之后，它会给我以下错误。

您可能正在尝试为多个请求重用 DbContext 实例。您的 DI 容器似乎将事物注册为单例。 DbContext 应按请求确定范围。

Answer 2

下面的代码帮助我找到我的解决方案，只需在 Attach() while update 之前调用此方法：

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);
}