public UserManagerDBContext DbContext { get { return _localCtx.Value; } }

public TEntity FindSingle(Expression<Func<TEntity,bool>> exp = null)
{
  return DbContext.Set<TEntity>().AsNoTracking().FirstOrDefault(exp);
}

public IQueryable<TEntity> Find(Expression<Func<TEntity,bool>> exp = null)
{
  return Filter(exp);
}

public IQueryable<TEntity> Find(Expression<Func<TEntity,bool>> expression,Expression<Func<TEntity,dynamic>> sortPredicate,SortOrder sortOrder,int pageNumber,int pageSize)
{
  if (pageNumber <= 0)
    throw new ArgumentOutOfRangeException("pageNumber",pageNumber,"pageNumber must great than or equal to 1.");
  if (pageSize <= 0)
    throw new ArgumentOutOfRangeException("pageSize",pageSize,"pageSize must great than or equal to 1.");

  var query = DbContext.Set<TEntity>().Where(expression);
  var skip = (pageNumber - 1) * pageSize;
  var take = pageSize;
  if (sortPredicate == null)
    throw new InvalidOperationException("Based on the paging query must specify sorting fields and sort order.");

  switch (sortOrder)
  {
    case SortOrder.Ascending:
      var pagedAscending = query.SortBy(sortPredicate).Skip(skip).Take(take);

      return pagedAscending;
    case SortOrder.Descending:
      var pagedDescending = query.SortByDescending(sortPredicate).Skip(skip).Take(take);
      return pagedDescending;
  }

  throw new InvalidOperationException("Based on the paging query must specify sorting fields and sort order.");
}

public int GetCount(Expression<Func<TEntity,bool>> exp = null)
{
  return Filter(exp).Count();
}

public void Add(TEntity entity)
{
  DbContext.Set<TEntity>().Add(entity);
}

public void Update(TEntity entity)
{
  DbContext.Entry(entity).State = EntityState.Modified;
}

public void Delete(TEntity entity)
{
  DbContext.Entry(entity).State = EntityState.Deleted;
  DbContext.Set<TEntity>().Remove(entity);
}

public void Delete(ICollection<TEntity> entityCollection)
{
  if(entityCollection.Count ==0)
    return;

  DbContext.Set<TEntity>().Attach(entityCollection.First());
  DbContext.Set<TEntity>().RemoveRange(entityCollection);
}

private IQueryable<TEntity> Filter(Expression<Func<TEntity,bool>> exp)
{
  var dbSet = DbContext.Set<TEntity>().AsQueryable();
  if (exp != null)
    dbSet = dbSet.Where(exp);
  return dbSet;
}

public void Commit()
{
  DbContext.SaveChanges();
}

}

public class UserRepository :BaseRepository,IUserRepository
{

}