EF Repository Foundations

EFRepository<T>

    public class EFRepository<T> : IRepository<T> where T : class
    {
        public EFRepository(DbContext dbContext)
        {
            if (dbContext == null) 
                throw new ArgumentNullException("dbContext");
            DbContext = dbContext;
            DbSet = DbContext.Set<T>();
        }

        protected DbContext DbContext { get; set; }

        protected DbSet<T> DbSet { get; set; }

        public virtual IQueryable<T> GetAll()
        {
            return DbSet;
        }

        public virtual T GetById(int id)
        {
            return DbSet.FirstOrDefault(PredicateBuilder.GetByIdPredicate<T>(id));
        }

        public virtual void Add(T entity)
        {
            DbEntityEntry dbEntityEntry = DbContext.Entry(entity);
            if (dbEntityEntry.State != EntityState.Detached)
            {
                dbEntityEntry.State = EntityState.Added;
            }
            else
            {
                DbSet.Add(entity);
            }
        }

        public virtual void Update(T entity)
        {
            DbEntityEntry dbEntityEntry = DbContext.Entry(entity);
            if (dbEntityEntry.State == EntityState.Detached)
            {
                DbSet.Attach(entity);
            }  
            dbEntityEntry.State = EntityState.Modified;
        }

        public virtual void Delete(T entity)
        {
            DbEntityEntry dbEntityEntry = DbContext.Entry(entity);
            if (dbEntityEntry.State != EntityState.Deleted)
            {
                dbEntityEntry.State = EntityState.Deleted;
            }
            else
            {
                DbSet.Attach(entity);
                DbSet.Remove(entity);
            }
        }

        public virtual void Delete(int id)
        {
            var entity = GetById(id);
            if (entity == null) return; // not found; assume already deleted.
            Delete(entity);
        }
    }

IRepository<T>

    public interface IRepository<T> where T : class
    {
        IQueryable<T> GetAll();
        T GetById(int id);
        void Add(T entity);
        void Update(T entity);
        void Delete(T entity);
        void Delete(int id);
    }