I have been learning the Repository and Unit of Work patterns from various sources, including here:
If you browse to thr link above to Creating a Unit of Work Class there is the following:
private GenericRepository<Department> departmentRepository;
private GenericRepository<Course> courseRepository;
The which is fine, but I wanted to have a go at extending the Unit of Work class that Generic and setup a collection of GenericRepositories so i can update then dynamnically based on the model I pass through.
I ultimately want to do the following in my Controller:
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());
}
}
So here is my classes and interfaces so far:
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
/// /// Repository Class for looking afer Entities /// CRUD Operations /// /// 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);
}
}
}
Now I know the implementation of repositories Dictionary and the method Repository are incorrect (Generic Types are wrong) because in my lambda expression it cannot resolve the ledgeruser LastName.
var view = unitOfWork.Repository(ledgeruser).Get(l => l.LastName == "smith");
Am I over engineering the issue, or is there a good clean way to create Generic Unit of Work with my collection of Generic Repositories, which are set and created based on the model object give (LedgerUser for e.g. above).
