Илья

public async Task<Teacher> GetTeacher(Guid teacherId)
        {
            var teacher = await _uniDbContext
                                        .Teachers
                                        .Include(x => x.Cources)
                                        .FirstOrDefaultAsync(t => t.Id == teacherId);
            return teacher;
        }

public async Task<bool> IsDublicated(string label)
{
     var existedProduct = await _context.Set<Product>()
                .FirstOrDefaultAsync(property => property.Label.ToLower() == label.ToLower());
     return existedProduct != null;
}

if (await _unitOfWork.ProductRepository.IsDublicated(product.Label))
{
     throw new DataDublication("Label already exists.");
}

Task<Device[]> FilteredDevices(params Expression<Func<Device, bool>> filters)
{
    IQueryable<Device> query = this.Entities;
    foreach(var filter in filters)
    {
        query = query.Where(filter);
    }
    return query.AsNoTracking().ToArrayAsync();
}

var gradesWithStudents = await _context.Grades.Include(o => o.Students).ToArrayAsync();

Add-Migration -Project MyAwesomeProject -StartupProject MyAwesomeProject -Name MyAwesomeMigration