it is possible to implement FindBy method in Entity framework while we have this GenericRepository class :
public class Repository<T> : IRepository<T> where T : class, IAggregateRoot
{
private readonly DbSet<T> _entitySet;
public IQueryable<T> FindBy(Expression<Func<T, bool>> predicate)
{
//IQueryable<T> query=_entitySet.
}
}
how can I Implement FindBy in this case !??
My Repository has the following method to return a single entity by a given expression.
public T FindSingle(Expression<Func<T, bool>> predicate) {
return _entitySet.FirstOrDefault(predicate);
}
Now the caller can use any expression to get a single entity, like
var entity = _repository.FindSingle(entity=> entity.Id == 23);
or
var entity = _repository.FindSingle(entity=> entity.Name == "Hello World");
If your interface IAggregateRoot defines a property Id you can also add an an explicit method to your generic interface to get a single entity by its Id.
public interface IAggregateRoot {
int Id {get;}
}
public class GenericRepository {
public T FindSingleById(int id) {
return _entitySet.FirstOrDefault(entity=>entity.Id == id);
}
}
This should work
public class Repository<T> : IRepository<T> where T : class, IAggregateRoot
{
private readonly DbSet<T> _entitySet;
public IQueryable<T> FindBy(Expression<Func<T, bool>> predicate)
{
return _entitySet.Where(predicate).
}
}
Related
First question here, I hope I'm doing it right.
I'm using Entity Framework Core 5.0 (Code First) with an onion architecture (data/repo/service/mvc) and so I have a service for each table (almost).
It's work well but now I need to manage (get, insert, update, delete) about 150 tables which all have the same structure (Id, name, order).
I have added each of them as Entity class and their DbSet too in my DbContext, but I don't want to make 150 services, I would like to have a generic one .
How can I bind it to my generic repository ?
public class Repository<T> : IRepository<T> where T : BaseEntity
{
private readonly ApplicationContext context;
private DbSet<T> entities;
private readonly RepositorySequence repoSequence;
private string typeName { get; set; }
public Repository(ApplicationContext context)
{
this.context = context;
entities = context.Set<T>();
this.repoSequence = new RepositorySequence(context);
this.typeName = typeof(T).Name;
}
public T Get(long plng_Id)
{
return entities.SingleOrDefault(s => s.Id == plng_Id);
}
[...]
}
In an ideal world, would like to have something like this :
public async Task Insert(dynamic pdyn_Entity)
{
Type DynamicType = Type.GetType(pdyn_Entity);
Repository<DynamicType> vobj_Repo = new Repository<DynamicType>(mobj_AppContext);
long Id = await vobj_Repo.InsertAsync(pdyn_Entity);
}
But I can try to get type from DbSet string Name too, I just managed to retrieve some data :
public IEnumerable<object> GetAll(string pstr_DbSetName)
{
return ((IEnumerable<BaseEntity>)typeof(ApplicationContext).GetProperty(pstr_DbSetName).GetValue(mobj_AppContext, null));
}
I've tried the following method (2.0 compatible apparently) to get the good DbSet, not working neither (no Query) : https://stackoverflow.com/a/48042166/10359024
What am I missing?
Thanks a lot for your help
Not sure why you need to get type?
You can use something like this.
Repository.cs
public class Repository<T> : IRepository<T> where T : BaseEntity
{
private readonly ApplicationContext context;
private DbSet<T> entities;
public Repository(ApplicationContext context)
{
this.context = context;
entities = context.Set<T>();
}
public List<T> Get()
=> entities.ToList();
public T Get(long plng_Id)
=> entities.Find(plng_Id);
public long Save(T obj)
{
if (obj.ID > 0)
entities.Update(obj);
else
entities.Add(obj);
return obj.ID;
}
public void Delete(T obj)
=> entities.Remove(obj);
}
Then you can use either one of these 2 options you want
Multiple repositories following your tables
UserRepository.cs
public class UserRepository : Repository<User> : IUserRepository
{
private readonly ApplicationContext context;
public UserRepository(ApplicationContext context)
{
this.context = context;
}
}
BaseService.cs
public class BaseService : IBaseService
{
private readonly ApplicationContext context;
private IUserRepository user;
private IRoleRepository role;
public IUserRepository User { get => user ??= new UserRepository(context); }
public IRoleRepository Role { get => user ??= new RoleRepository(context); }
public BaseService(ApplicationContext context)
{
this.context = context;
}
}
If you are lazy to create multiple repositories, can use this way also. Your service just simple call Repository with entity name.
BaseService.cs
public class BaseService : IBaseService
{
private readonly ApplicationContext context;
private IRepository<User> user;
private IRepository<Role> role;
public IRepository<User> User { get => user ??= new Repository<User>(context); }
public IRepository<Role> Role { get => role ??= new Repository<Role>(context); }
public BaseService(ApplicationContext context)
{
this.context = context;
}
}
Finally, you can call service like this. You can use multiple services instead of BaseService if you want.
HomeController.cs
public class HomeController : Controller
{
private readonly IBaseService service;
public HomeController(IBaseService service)
{
this.service = service;
}
public IActionResult Index()
{
var user = service.User.Get();
return View(user);
}
public IActionResult Add(User user)
{
var id = service.User.Save(user);
return View();
}
}
I suggest to use first option (multiple repositories) because you may need to customise functions in own repository in future. And create service class following your controller name. For example, you have HomeController, UserController, etc. Create HomeService, UserService and link them with BaseService so that you can create customised functions in their own service class.
I assume you have a base entity like this:
public class BaseEntity
{
[Key]
public int Id { get; set; }
public string Name { get; set; }
public string Order { get; set; }
}
Then you can do CRUD operations in your generic repository like this:
public int Create(T item)
{
if (item == null) return 0;
entities.Add(item);////SaveChanges
return item.Id;
}
public void Update(T updatedItem)
{
context.SetModified(updatedItem);//SaveChanges
}
public IQueryable<T> All()
{
return entities();
}
And in each of the methods you have access to your 3 common fields in BaseEntity
Thank you all for your responses.
I need to have the type because I am using a blazor component which automatically binds to these tables. This component has the name of the desired entity class (in string) as a parameter. Thanks to #Asherguru's response I was able to find a way to do this:
1 - I made a 'SedgmentEntity' Class :
public abstract class SegmentEntity : ISegmentEntity
{
public abstract long Id { get; set; }
public abstract string Name { get; set; }
public abstract short? Order { get; set; }
}
2 - A SegmentRepository which is typed via Reflection:
public class SegmentRepository : ISegmentRepository
{
private readonly ApplicationContext context;
private readonly RepositorySequence repoSequence;
public SegmentRepository(ApplicationContext context)
{
this.context = context;
this.repoSequence = new RepositorySequence(context);
}
public async Task<long> Insert(string pstr_EntityType, SegmentEntity pobj_Entity)
{
Type? vobj_EntityType = Assembly.GetAssembly(typeof(SegmentEntity)).GetType("namespace.Data." + pstr_EntityType);
if (vobj_EntityType != null)
{
// create an instance of that type
object vobj_Instance = Activator.CreateInstance(vobj_EntityType);
long? nextId = await repoSequence.GetNextId(GetTableName(vobj_EntityType));
if (nextId == null)
{
throw new TaskCanceledException("Sequence introuvable pour " + vobj_EntityType.FullName);
}
PropertyInfo vobj_PropId = vobj_EntityType.GetProperty("Id");
vobj_PropId.SetValue(vobj_Instance, nextId.Value, null);
PropertyInfo vobj_PropName = vobj_EntityType.GetProperty("Name");
vobj_PropName.SetValue(vobj_Instance, pobj_Entity.Name, null);
PropertyInfo vobj_PropOrder = vobj_EntityType.GetProperty("Order");
vobj_PropOrder.SetValue(vobj_Instance, pobj_Entity.Order, null);
return ((SegmentEntity)context.Add(vobj_Instance).Entity).Id;
}
}
public IEnumerable<object> GetAll(string pstr_EntityType)
{
Type? vobj_EntityType = Assembly.GetAssembly(typeof(SegmentEntity)).GetType("namespace.Data." + pstr_EntityType);
if (vobj_EntityType != null)
{
PropertyInfo vobj_DbSetProperty = typeof(ApplicationContext).GetProperties().FirstOrDefault(prop =>
prop.PropertyType.FullName.Contains(vobj_EntityType.FullName));
return (IEnumerable<object>)vobj_DbSetProperty.GetValue(context, null);
}
return null;
}
}
I still have to handle the Get and the Delete functions but it should be fine.
Then I will be able to create a single service which will be called by my component.
Thanks again !
I am implementing Repository Pattern in one of my project based on ASP.NET MVC4 and N-Tier Architecture. I am little confused as how to implement Custom Membership with Repository Pattern. Here are how I have implemented my classes so far.
//Generic Repository
public interface IRepository<T> where T : class
{
void Add(T entity);
void Delete(T entity);
void Update(T entity);
IQueryable<T> GetAll();
T FindBy(Expression<Func<T, bool>> expression);
IQueryable<T> FilterBy(Expression<Func<T, bool>> expression);
}
//Repository Base Class
public abstract class Repository<T> : IRepository<T> where T : class
{
private STNDataContext _stnDataContext;
private readonly IDbSet<T> _dbSet;
protected Repository(IDatabaseFactory databaseFactory)
{
DatabaseFactory = databaseFactory;
_dbSet = StnDataContext.Set<T>();
}
protected IDatabaseFactory DatabaseFactory { get; private set; }
public STNDataContext StnDataContext
{
get { return _stnDataContext ?? (_stnDataContext = new STNDataContext()); }
}
public void Add(T entity)
{
_dbSet.Add(entity);
_stnDataContext.Commit();
}
public void Delete(T entity)
{
_dbSet.Remove(entity);
}
public void Update(T entity)
{
_dbSet.Attach(entity);
_stnDataContext.Entry(entity).State = EntityState.Modified;
_stnDataContext.Commit();
}
public IQueryable<T> GetAll()
{
return _dbSet.ToList().AsQueryable();
}
public T FindBy(Expression<Func<T, bool>> expression)
{
return FilterBy(expression).SingleOrDefault();
}
public IQueryable<T> FilterBy(Expression<Func<T, bool>> expression)
{
return GetAll().Where(expression).AsQueryable();
}
//User Repository Interface
public interface IUserRepository : IRepository<User>
{
}
//User Repository
public class UserRepository : Repository<User>, IUserRepository
{
public UserRepository(IDatabaseFactory databaseFactory)
: base(databaseFactory)
{
}
}
//Heres my Business Logic Layer
//Generic Service Interface
public interface IService<T>
{
void Add(T entity);
void Delete(T entity);
void Update(T entity);
IEnumerable<T> GetAll();
T FindBy(Expression<Func<T, bool>> expression);
IEnumerable<T> FilterBy(Expression<Func<T, bool>> expression);
}
//Service Base
public class Service<T> : IService<T> where T : class
{
public void Add(T entity)
{
throw new NotImplementedException();
}
public void Delete(T entity)
{
throw new NotImplementedException();
}
public void Update(T entity)
{
throw new NotImplementedException();
}
public IEnumerable<T> GetAll()
{
throw new NotImplementedException();
}
public T FindBy(Expression<Func<T, bool>> expression)
{
throw new NotImplementedException();
}
public IEnumerable<T> FilterBy(Expression<Func<T, bool>> expression)
{
throw new NotImplementedException();
}
}
//User Service Interface
public interface IUserService : IService<User>
{
}
//User Service Implementation
public class UserService : Service<User>, IUserService
{
private readonly IUserRepository _userRepository;
private readonly IRoleRepository _roleRepository;
public UserService(IUserRepository userRepository, IRoleRepository roleRepository)
{
_userRepository = userRepository;
_roleRepository = roleRepository;
}
public IList<User> GetAllUsers()
{
return _userRepository.GetAll().ToList();
}
public User GetUser(int id)
{
return _userRepository.FindBy(x => x.UserId == id);
}
public User GetUser(string userName)
{
return _userRepository.FindBy(x => x.Username.Equals(userName));
}
public void CreatUser(User user)
{
_userRepository.Add(user);
}
public IList<User> GetUsersForRole(string roleName)
{
return _userRepository.FilterBy(x => x.Role.RoleName.Equals(roleName)).ToList<User>();
}
public IList<User> GetUsersForRole(int roleId)
{
return _userRepository.FilterBy(x => x.Role.RoleId == roleId).ToList<User>();
}
public IList<User> GetUsersForRole(Role role)
{
return GetUsersForRole(role.RoleId);
}
}
I am not very sure on Am I going the right way? If yes how do i implement my UserService class.
If no, what changes do i need to implement.
Any help on this is highly appreciable. Thanks in advance*strong text*
Your IService<T> looks an awfully lot like your IRepository<T> interface. That looks like a completely useless abstraction to me. Consumers can use the IRepository<T> abstraction directly. If your intension is to add features (such as cross-cutting concerns) to the IService<T> implementations; use decorators instead.
Besides, why have an empty (non-generic) IUserRepository? There is no use over using the IRepository<User> directly. If your intention is to add extra methods to this IUserRepository later on, please don't. This interface, and the implementations of this interface, will start growing too big, get hard to maintain, and become hard to extend parts of your code base, because you will be violating the Single Responsibility Principle. Instead, give custom -user specific- operations their own classes (one class per operation), hidden by a generic interface, just as you already do with the IRepository<T>.
The following two articles describe an attractive way of creating a more maintainable system by defining smaller focused classes that each encapsulate a single query or use case, which can be placed on top of your repository pattern:
Meanwhile… on the command side of my architecture
Meanwhile… on the query side of my architecture
Last note. Your UserService class, looks a lot like the MembershipProvider class from the .NET framework. Why not use that class? There is a very interesting library that allows you to create a membership provider for MVC in a more structured, dependency-friendly way. You should definitely take a look.
I need to have a CRUd operations on my class (CompetenceSpecific).
Competence has three derived classes - CompetenceFunction, CompetenceArea and CompetenceSpecifc
The error I recieved:
There are no EntitySets defined for the specified entity type 'CompetencyManagement.Domain.Entities.CompetenceFunction'. If 'CompetencyManagement.Domain.Entities.CompetenceFunction' is a derived type, use the base type instead. Parameter name: TEntity
How should I correct this? Please suggest a solution that would solve my problem. Thanks
Please check the code below, I removed some parts of the code for simplicity.
--MODEL
public class Competence
{
public int CompetenceID { get; set; }
public int CourseID { get; set; }
...
}
public class CompetenceFunction : Competence
{
}
--REPOSITORY and interfaces
public interface IRepository<T> where T : class
{
T GetById(object id);
IEnumerable<T> GetAll();
IEnumerable<T> Query(Expression<Func<T, bool>> filter);
void Add(T entity);
void Remove(T entity);
}
public abstract class Repository<T> : IRepository<T>
where T : class
{
protected IObjectSet<T> _objectSet;
public Repository(ObjectContext context)
{
_objectSet = context.CreateObjectSet<T>();
}
...
}
public class CompetenceFunctionRepository : Repository<CompetenceFunction>
{
public CompetenceFunctionRepository(ObjectContext context)
: base(context)
{
}
public override CompetenceFunction GetById(object id)
{
return _objectSet.SingleOrDefault(s => s.CompetenceID == (int)id);
}
}
--UNIT oF WORK
public interface IUnitOfWork
{
IRepository<CompetenceFunction> CompetenceFunctions { get; }
IRepository<CompetenceArea> CompetenceAreas { get; }
IRepository<CompetenceSpecific> CompetenceSpecifics { get; }
void Commit();
}
public class UnitOfWork : IUnitOfWork, IDisposable
{
private CompetenceFunctionRepository _competencefunction;
private CompetenceAreaRepository _competencearea;
private CompetenceSpecificRepository _competencespecifc;
public UnitOfWork(ObjectContext context)
{
if (context == null)
{
throw new ArgumentNullException("Context was not supplied");
}
_context = context;
}
#region IUnitOfWork Members
public IRepository<CompetenceFunction> CompetenceFunctions
{
get
{
if (_competencefunction == null)
{
_competencefunction = new CompetenceFunctionRepository(_context);
}
return _competencefunction;
}
}
public IRepository<CompetenceArea> CompetenceAreas
{
get
{
if (_competencearea == null)
{
_competencearea = new CompetenceAreaRepository(_context);
}
return _competencearea;
}
}
public IRepository<CompetenceSpecific> CompetenceSpecifics
{
get
{
if (_competencespecifc == null)
{
_competencespecifc = new CompetenceSpecificRepository(_context);
}
return _competencespecifc;
}
}
--Im getting an error in this part of Repository
public Repository(ObjectContext context)
{
_objectSet = context.CreateObjectSet<T>();
}
There are no EntitySets defined for the specified entity type 'CompetencyManagement.Domain.Entities.CompetenceFunction'. If 'CompetencyManagement.Domain.Entities.CompetenceFunction' is a derived type, use the base type instead. Parameter name: TEntity
Here's how I implement in the controller
private IUnitOfWork _unitOfWork;
var a = _unitOfWork.CompetenceFunctions.GetAll();
return View(a);
You have to get derived type by the OfType function, e.g.
context.CreateObjectSet<Competence>().OfType<CompetenceFunction>()
In your case that would mean that there is only a CompetenceRepository that serves all derivatives of Competence.
Edit
(After your comment)
First, UoW is meant for temporarily storing changes that should be dealt with in one batch (like changes to be committed to the database). GetAll and similar functions are repository stuff.
But do you need repositories? I like this post. When beginning to know EF, I would focus on the ins and outs of EF without getting distracted too much by surrounding architecture. E.g. start with services that at the inside communicate directly with the context and expose methods like GetCompetenceFunctions, GetCompetenceAreas (using OfType), and SaveCompetenceFunction, ....
You can address these service methods directly from action methods in the MVC controllers.
I am new to MVC, repository concept and dependency injection.
My repository and DAL looks like
public interface IRepository<TEntity> where TEntity : class
{
List<TEntity> FetchAll();
IQueryable<TEntity> Query { get; }
void Add(TEntity entity);
void Delete(TEntity entity);
void Save();
}
public class Repository<T> : IRepository<T> where T : class
{
private readonly DataContext _db;
public Repository(DataContext db)
{
_db = db;
}
#region IRepository<T> Members
public IQueryable<T> Query
{
get { return _db.GetTable<T>(); }
}
public List<T> FetchAll()
{
return Query.ToList();
}
public void Add(T entity)
{
_db.GetTable<T>().InsertOnSubmit(entity);
}
public void Delete(T entity)
{
_db.GetTable<T>().DeleteOnSubmit(entity);
}
public void Save()
{
_db.SubmitChanges();
}
#endregion
}
In Global.asax file I have
private void RegisterDependencyResolver()
{
var kernel = new StandardKernel();
kernel.
Bind(typeof(IRepository<>)).
To(typeof(Repository<>))
.WithConstructorArgument("db", new DataContext(ConfigurationManager.ConnectionStrings["ConnectionString"].ToString()));
DependencyResolver.SetResolver(new NinjectDependencyResolver(kernel));
}
but when I am trying to access repository I get "Object reference not set to an instance of an object". Do I understand correctly how Repository and Injection should work?
public class AdminController : Controller
{
private readonly IRepository<User> _userRepository;
public ActionResult Index()
{
var a = _userRepository.FetchAll(); //I get exception here
return View();
}
}
You get nullref because you don't set _userRepository. Set it in the AdminControllers constructor and Niject will inject it happily:
public class AdminController : Controller
{
private readonly IRepository<User> _userRepository;
public AdminController(IRepository<User> userRepository)
{
_userRepository = userRepository;
}
//...
}
You can read here more about the injection patterns with Ninject and how injection works.
In the web config file
<appSettings>
<add key="RepoSetting" value="Solution.DAL.OrderRepository"/>
</appSettings>
In the ninject web common class
private static void RegisterServices(Ikernel Kernel)
{
//kernl.Bind<Irepo>().To<CustRepo>();
string name = WebConfigurationManager.AppSettings["RepoSetting"];
Type repoToInject = Assembly.GetExecutingAssembly().GetType(name);
kernel.Bind<ICustomerRepository>().To(repoToInject
}
I have the following generic repository:
public class GenericRepository<TEntity> where TEntity : class {
private EFDbContext context;
private DbSet<TEntity> dbSet;
public GenericRepository(EFDbContext context) {}
public IEnumerable<TEntity> GetAll() {}
public IEnumerable<TEntity> Get(Expression<Func<TEntity, bool>> filter = null, Func<IQueryable<TEntity>, IOrderedQueryable<TEntity>> orderBy = null, string includeProperties = "") {}
public TEntity GetByID(int id) {}
public void Insert(TEntity entity) {}
public void Delete(int id) {}
public void Delete(TEntity entity) {}
public void Update(TEntity entity) {}
}
Now I understand how I can use this for my entities, but I don't understand what to do if an entity needs more than just these methods? Say I have an entity called 'Tournament' and I want to get all the groups in that tournament, where would the 'GetTournamentGroups' method go?
Should I, instead of using a generic repository, write a basic repository interface which all the entities' own interfaces inherit from and then just add the additional methods needed for each entity?
You could also simply use
var TournamentGroups = new List<Group>();
using( var GenericRepo = new GenericRepository<Group>())
{
TournamentGroups = GenericRepo.Get(group => group.TournamentId == tournamentId);
}
somewhere with your normal repository. It seems a little overkill to make a class which does this.
Method GetTournamentGroups() seems to belong to the layer above Repository layer:
class TournamentModel
{
private int tournamentId; // initialized in constructor
private GenericRepository<Group> repository; // initialized in constructor
IEnumerable<Group> GetTournamentGroups()
{
return repository.Get( group => group.TournamentId == tournamentId);
}
}
I'd recommend using IQueryable insteam of IEnumerable in your GenericRepository, though. It would be more flexible if you need to apply filters or sort expressions before you make an actual database query.