我一直在从各种来源学习存储库和工作单元模式，包括这里：
如果您浏览到上面的创建工作单元类的链接，则会出现以下内容：
private GenericRepository<Department> departmentRepository;
private GenericRepository<Course> courseRepository;
这很好，但我想尝试扩展 Generic 的 Unit of Work 类并设置 GenericRepositories 的集合，以便我可以根据我通过的模型动态更新。
我最终想在我的Controller中执行以下操作：
public class LedgerUserController : Controller
{
private GenericUnitOfWork unitOfWork = new GenericUnitOfWork();
LedgerUser ledgeruser = new LedgerUser();
public ActionResult Index()
{
//var ledgerusers = db.LedgerUsers.Include(l => l.Image).Include(l => l.UserType);
var view = unitOfWork.Repository(ledgeruser).Get(l => l.LastName == "smith");
return View(view.ToList());
}
}
所以到目前为止，这是我的类和接口：
IRepository.cs
/// <summary>
/// Generic Repository for CRUD Operations and methods
/// to locate entities within your store. This is not specific to which Data Access
/// tools your are using (Direct SQL, EF, NHibernate, etc).
/// </summary>
public interface IRepository<T> where T : class
{
//--Search Operations
IQueryable<T> GetAll();
IEnumerable<T> GetAllList();
IEnumerable<T> Get(Expression<Func<T,bool>> filter);
T GetIt(Expression<Func<T, bool>> filter);
T GetById(object id);
//--CRUD Operations
void Create(T entity);
void Update(T entity);
void Delete(T entity);
}
GenericRepository.cs
/// /// 用于查找实体的存储库类 /// CRUD 操作 /// /// public class GenericRepository : IRepository where TEntity : class {
internal AccountsContext context;
internal DbSet<TEntity> dbSet;
internal IQueryable<TEntity> query;
/// <summary>
/// Default Constructor.
/// </summary>
/// <param name="context"></param>
public GenericRepository(AccountsContext context)
{
this.context = context;
this.dbSet = context.Set<TEntity>();
}
#region Methods
#region Search Functionality
/// <summary>
/// Obtain the whole Entity to query if needed.
/// </summary>
/// <returns>IQueryable object.</returns>
public virtual IQueryable<TEntity> GetAll()
{
IQueryable<TEntity> query = dbSet;
return query;
}
/// <summary>
/// Obtain the whole Entity to Enumerate throught if needed.
/// </summary>
/// <returns>IEnumerble object.</returns>
public virtual IEnumerable<TEntity> GetAllList()
{
IQueryable<TEntity> query = dbSet;
return query.ToList();
}
/// <summary>
/// Locate an Entity by its indexed id.
/// </summary>
/// <param name="id"></param>
/// <returns></returns>
public virtual TEntity GetById(object id)
{
return dbSet.Find(id);
}
/// <summary>
/// Gets a collection based on LINQ lambda expressions
/// </summary>
/// <param name="filter">Lambda Expression</param>
/// <returns>Query</returns>
public virtual IEnumerable<TEntity> Get(Expression<Func<TEntity, bool>> filter)
{
query = dbSet;
if (filter != null)
{
query = query.Where(filter);
}
return this.query.ToList();
}
/// <summary>
/// Gets one record based on a one-to-one relationship.
/// </summary>
/// <param name="filter">Lambda Expression.</param>
/// <returns>One record.</returns>
public virtual TEntity GetIt(Expression<Func<TEntity, bool>> filter)
{
IQueryable<TEntity> query = dbSet;
return query.SingleOrDefault(filter);
}
#endregion
#region CRUD Functionality
/// <summary>
/// Used to create a new entity into the database.
/// </summary>
/// <param name="entity">Entity to create.</param>
public virtual void Create(TEntity entity)
{
dbSet.Add(entity);
}
/// <summary>
/// Used to update an entity that already exists in the
/// database.
/// </summary>
/// <param name="entity">Entity to update.</param>
public virtual void Update(TEntity entity)
{
dbSet.Attach(entity);
context.Entry(entity).State = EntityState.Modified;
}
/// <summary>
/// Used to delete an entity from the database.
/// </summary>
/// <param name="entity">Entity to delete.</param>
public virtual void Delete(TEntity entity)
{
if (context.Entry(entity).State == EntityState.Detached)
{
dbSet.Attach(entity);
}
dbSet.Remove(entity);
}
#endregion
#endregion
}
#endregion
GenericUnitOfWork.cs：
/// <summary>
/// Unit of work class that handles multiple Repositories
/// and shares the context.
/// </summary>
public class GenericUnitOfWork : IUnitOfWork
{
private AccountsContext context = new AccountsContext();
Dictionary<string, GenericRepository<IRepository<IRepositoryEntity>>> repostories = null;
/// <summary>
/// Generic Repository method which checks the repository is available if not,
/// it sets it up.
/// </summary>
/// <param name="entity">Entity</param>
/// <returns>Repository to use.</returns>
public GenericRepository<IRepository<IRepositoryEntity>> Repository (IRepositoryEntity entity)
{
string index = entity.GetType().ToString();
if (!repostories.ContainsKey(index))
{
//Reflections to create the repoositiory if it is not needed.
Type type1 = typeof(GenericRepository<>);
Type[] typeArgs = {typeof(IRepositoryEntity)};
Type constructed = type1.MakeGenericType(typeArgs);
object o = Activator.CreateInstance(constructed);
if(o is GenericRepository<IRepository<IRepositoryEntity>>)
{
var rep = (GenericRepository<IRepository<IRepositoryEntity>>)o;
rep.context = this.context;
repostories.Add(index, rep);
}
}
return this.repostories[index];
}
/// <summary>
/// Save method.
/// </summary>
public void Save()
{
context.SaveChanges();
}
private bool disposed = false;
/// <summary>
/// Dispose the conxtext when finished.
/// </summary>
/// <param name="disposing"></param>
protected virtual void Dispose(bool disposing)
{
if (!this.disposed)
{
if (disposing)
{
context.Dispose();
}
}
this.disposed = true;
}
public void Dispose()
{
Dispose(true);
GC.SuppressFinalize(this);
}
}
}
现在我知道存储库字典的实现和存储库方法不正确（通用类型错误），因为在我的 lambda 表达式中它无法解析 ledgeruser LastName。
var view = unitOfWork.Repository(ledgeruser).Get(l => l.LastName == "smith");
我是否过度设计了这个问题，或者是否有一种很好的干净方法来使用我的通用存储库集合创建通用工作单元，这些存储库是基于模型对象给出的（例如上面的 LedgerUser）设置和创建的。