使用 Unity 的 MVC 控制器构造函数注入中的工作单元和存储库模式不对数据库进行任何更改

Question

1.) I am a building new MVC application with 3 tier project architecture having:

1. Common Project with entities
2. Business/Service holding interfaces and logic classes and
3. Data holding repositories, interfaces, DbContext and UnitOfWork classes. I am using Unity Config to register dependencies, DbContext and UnitOfWork .

2.) I created a repository for each table and one generic repository that does basic CRUD operations.

Example Entity residing in Common Project:

public class MenuSecd
{
    [Key, Column(Order = 0)]
    public string prg_module { get; set; }
    [Key, Column(Order = 1)]
    public int prg_numb { get; set; }
    [Key, Column(Order = 2)]
    public string menu_level { get; set; }
}

My generic Entity Logic Interface residing in Business Project:

public interface IEntityLogic<T> : ILogic where T : class
{
    void Create(T entity);
    void Delete(T entity);
    IEnumerable<T> GetAll();
    void Update(T entity);
}

Entity Logic Class:

public abstract class EntityLogic<T> : IEntityLogic<T> where T : class
{
    IUnitOfWork _unitOfWork;
    IGenericRepository<T> _repository;

    public EntityLogic(IUnitOfWork unitOfWork, IGenericRepository<T> repository)
    {
        _unitOfWork = unitOfWork;
        _repository = repository;
    }

    public virtual void Create(T entity)
    {
        if(entity == null)
        {
            throw new ArgumentNullException(nameof(entity));
        }

        _repository.Add(entity);
        _unitOfWork.Commit();
    }
}

Example Business Logic class for the entity defined in Common Project:

public class MenuSecdLogic : EntityLogic<MenuSecd>, IMenuSecdLogic
{
    IUnitOfWork _unitOfWork;
    IMenuSecdRepository _repository;
    public MenuSecdLogic(IUnitOfWork unitOfWork, IMenuSecdRepository repository) : base(unitOfWork, repository)
    {
        _unitOfWork = unitOfWork;
        _repository = repository;
    }

    public List<MenuSecd> GetItems(string usrgrp_id)
    {
        return _repository.GetItems(usrgrp_id);
    }
}

My Generic Repository in Data Project looks like:

public abstract class GenericRepository<T> : IGenericRepository<T> where T : class
{
    protected DbContext _entities;
    protected readonly IDbSet<T> _dbset;
    public GenericRepository(DbContext context)
    {
        _entities = context;
        _dbset = context.Set<T>();
    }
    public virtual T Add(T entity)
    {
        return _dbset.Add(entity);
    }

    public virtual T Delete(T entity)
    {
        return _dbset.Remove(entity);
    }

    public virtual void Edit(T entity)
    {
        _entities.Entry(entity).State = EntityState.Modified;
    }
}

Repository Interface for the same Entity is defined as:

public interface IMenuSecdRepository : IGenericRepository<MenuSecd>
{
    List<MenuSecd> GetItems(string usrgrp_id);
}

Repository class for above mentioned interface is:

public class MenuSecdRepository : GenericRepository<MenuSecd>, IMenuSecdRepository
{
    public MenuSecdRepository(DbContext context) : base(context)
    {

    }

    public List<MenuSecd> GetItems(string usrgrp_id)
    {
        return _dbset.Where(m => m.usrgrp_id == usrgrp_id).ToList();
    }
}

My DbContext looks like:

public class DashboardContext : DbContext
{
    public DashboardContext() : base("Name=DBEntities")
    {

    }

    public DbSet<MenuSecd> menusecd { get; set; }

    public override int SaveChanges()
    {
        var modifiedEntries = ChangeTracker.Entries().Where(x => x.State == EntityState.Added || x.State == EntityState.Modified);
        //future custom implementation like auditing
        return base.SaveChanges();
    }
}

My UnitOfWork looks like:

public sealed class UnitOfWork : IUnitOfWork
{
    private DbContext _dbContext;
    public UnitOfWork(DbContext context)
    {
        _dbContext = context;
    }

    public int Commit()
    {
        return _dbContext.SaveChanges();
    }

    //disposes current object
    public void Dispose()
    {
        Dispose(true);
        GC.SuppressFinalize(this);
    }
    //disposes all external resources
    private void Dispose(bool disposing)
    {
        if (disposing)
        {
            if (_dbContext != null)
            {
                _dbContext.Dispose();
                _dbContext = null;
            }
        }
    }
}

My controller:

public class DashController : Controller
{
    private readonly IMenuSecdLogic _menuSecdLogic;
    public DashController(IMenuSecdLogic menuSecdLogic)
    {
         _menuSecdLogic = menuSecdLogic;          
    }
    public void Save()
    {
         var menuSecd = new menuSecd();
         //populate all fields for entity MenuSecd
         _menuSecdLogic.Create(menuSecd);
    }
}

My Unity Config in App_Start looks like :

public static void RegisterTypes(IUnityContainer container)
{
    container.RegisterType<DbContext, DashboardContext>();
    container.RegisterType<IUnitOfWork, UnitOfWork>();
    container.RegisterType(typeof(IGenericRepository<>), typeof(GenericRepository<>));
    container.RegisterType<IMenuSecdLogic, MenuSecdLogic>();
    container.RegisterType<IMenuSecdRepository, MenuSecdRepository>();
}

So when run above project everything builds fine. But when controller calls:

_menuSecdLogic.Create(menuSecd);

It reaches Entity Logic and adds a new entity to _repository at :

_repository.Add(entity);
_unitOfWork.Commit();

But when it hits next line to actually save it to database which is :

return _dbContext.SaveChanges();

in UnitOfWork.cs file. It comes to dashboardContext where it finally have to save it to database. But it does execute :

var modifiedEntries = ChangeTracker.Entries().Where(x => x.State == EntityState.Added || x.State == EntityState.Modified);
    return base.SaveChanges();

But nothing changes in database. There will be no record in database. To test I have added modifiedEntries to see if it is in context or not. By the time control reaches this point I see no modified entries at all. But in EntityLogic.cs it does add a new entity to local entities in repository. I am not sure what is happening with UnitOfWork here. I ran SQL Profiler to see if it is hitting database or not. Interestingly it is not hitting database at all. But if my make following changes to EntityLogic like this:

public virtual void Create(T entity)
{
    if(entity == null)
    {
        throw new ArgumentNullException(nameof(entity));
    }

    _repository.Add(entity);
    _repository.Save();
    //_unitOfWork.Commit();
}

It hits Database and records gets saved fine. But I am not getting why it is neither tracking changes nor hitting database if I use _unitOfWork.Commit() which I want to do. Please help.

Answer 1

It looks like your issue is the scope of your DbContext . Your UnitOfWork and GenericRepository<T> classes are getting different instances.

Not super familiar with Unity, but it looks like you want to use something like this for your DbContext registration:

container.RegisterType<DbContext, DashboadContext>(new PerRequestLifetimeManager());

This will create a single DashboardContext for each request, and your UnitOfWork and GenericRepository<T> classes will be working within the same context.