system.invalidoperationException：无法跟踪实体类型的实例，因为{＆＃x27; id＆＃x27;}的另一个具有相同密钥值的实例已经存在

Question

我在Azure上部署了一个API，其中我有一个crcart实体。我想确保，如果已经有一个与用户关联的购物车和具有“保存”状态的客户，那么您将无法使用该状态添加更多。

这里的问题是，我在crcart服务上对我的帖子方法进行了验证，并且可以正常工作，但是在我的put方法上却没有。

这是错误：

System.InvalidOperationException: The instance of entity type 'CrCart' cannot be tracked because another instance with the same key value for {'Id'} is already being tracked. When attaching existing entities, ensure that only one entity instance with a given key value is attached. Consider using...

这是我的insert和update方法的代码：

public async Task Insert(CrCart cart)
        {
            var user = await _unitOfWork.CrUserRepository.GetById(cart.IdUser);
            var customer = await _unitOfWork.CrCustomerRepository.GetById(cart.IdCustomer);

            var carts = _unitOfWork.CrCartRepository.GetAll();
            carts = carts.Where(x => x.IdCustomer == cart.IdCustomer && x.Status == "Saved" && x.IdUser == cart.IdUser);

            if (user == null)
            {
                throw new BusinessException("El usuario introducido no existe");
            }

            if (customer == null)
            {
                throw new BusinessException("El cliente introducido no existe");
            }

            if (carts.Count() >= 1 && cart.Status == "Saved") {

                throw new BusinessException("Ya existe un carrito con estado -Saved- asignado al cliente " +
                    customer.Name);
            }   

            await _unitOfWork.CrCartRepository.Insert(cart);
            await _unitOfWork.SaveChangesAsync();
        }

        public async Task<bool> Update(CrCart cart)
        {
            var user = await _unitOfWork.CrUserRepository.GetById(cart.IdUser);
            var customer = await _unitOfWork.CrCustomerRepository.GetById(cart.IdCustomer);

            var carts = _unitOfWork.CrCartRepository.GetAll();
            carts = carts.Where(x => x.IdCustomer == cart.IdCustomer && x.Status == "Saved" && x.IdUser == cart.IdUser);

            if (user == null)
            {
                throw new BusinessException("El usuario introducido no existe");
            }

            if (customer == null)
            {
                throw new BusinessException("El cliente introducido no existe");
            }

            if (carts.Count() >= 1 && cart.Status == "Saved")
            {

                throw new BusinessException("Ya existe un carrito con estado -Saved- asignado al cliente " +
                    customer.Name);
            }

            _unitOfWork.CrCartRepository.Update(cart);
            await _unitOfWork.SaveChangesAsync();

            return true;

        }

我已经掌握了服务范围，因此这不是问题。请提供帮助，因为我不知道这是什么原因引起的，我有一个截止日期。谢谢。

edit

我的baseerpository我有通用方法

 public class BaseRepository<T> : IBaseRepository<T> where T: BaseEntity
    {
        private readonly db_crijoyaContext _context;
        protected readonly DbSet<T> _entities;

        public BaseRepository(db_crijoyaContext context)
        {
            _context = context;
            _entities = context.Set<T>();
        }

        public IEnumerable<T> GetAll()
        {
           return _entities.AsEnumerable();
        }

        public async Task<T> GetById(int id)
        {
            return await _entities.FindAsync(id);
        }

        public async Task Insert(T entity)
        {
            await _entities.AddAsync(entity);
            
            //await _context.SaveChangesAsync();
        }

        public void Update(T entity)
        {
            
            _entities.Update(entity);
            
            //await _context.SaveChangesAsync();
        }

        public async Task Delete(int id)
        {
            T entity = await GetById(id);
            _entities.Remove(entity);

            //await _context.SaveChangesAsync();

        }

    }

和我的unitofwork我拥有所有存储库

public class UnitOfWork : IUnitOfWork 
    {
        private readonly db_crijoyaContext _context;
        private readonly ICrProductRepository _productRepsitory;
        private readonly IBaseRepository<CrCompany> _companyRepository;
        private readonly IBaseRepository<CrCategory> _categoryRepository;
        private readonly IBaseRepository<CrCart> _cartRepository;
        private readonly IBaseRepository<CrCustomer> _customerRepository;
        private readonly IBaseRepository<CrUser> _userRepository;
        private readonly IBaseRepository<CrOrder> _orderRepository;
        private readonly IBaseRepository<CrCity> _cityRepository;
        private readonly ICrUserInfoRepository _userInfoRepository;
        private readonly ICrCountryRepository _countryRepository;

        public UnitOfWork(db_crijoyaContext context)
        {
            _context = context;
        }

        public ICrProductRepository CrProductRepository => _productRepsitory ?? new CrProductRepository(_context);
        public IBaseRepository<CrCategory> CrCategoryRepository => _categoryRepository ?? new BaseRepository<CrCategory>(_context);
        public IBaseRepository<CrCompany> CrCompanyRepository => _companyRepository ?? new BaseRepository<CrCompany>(_context);
        public IBaseRepository<CrUser> CrUserRepository => _userRepository ?? new BaseRepository<CrUser>(_context);
        public IBaseRepository<CrCart> CrCartRepository => _cartRepository ?? new BaseRepository<CrCart>(_context);
        public IBaseRepository<CrCustomer> CrCustomerRepository => _customerRepository ?? new BaseRepository<CrCustomer>(_context);
        public IBaseRepository<CrOrder> CrOrderRepository => _orderRepository ?? new BaseRepository<CrOrder>(_context);
        public IBaseRepository<CrCity> CrCityRepository => _cityRepository ?? new BaseRepository<CrCity>(_context);
        public ICrUserInfoRepository CrUserInfoRepository => _userInfoRepository ?? new CrUserInfoRepository(_context);
        public ICrCountryRepository CrCountryRepository => _countryRepository ?? new CrCountryRepository(_context);

        public void Dispose()
        {
            if(_context != null)
            {
                _context.Dispose();
            }
        }

        public void SaveChanges()
        {
            _context.SaveChanges();
        }

        public async Task SaveChangesAsync()
        {
            await _context.SaveChangesAsync();
        }

edgrang> edit> edit 2

这是我不知道是否正确完成的工作代码

public async Task<bool> Update(CrCart cart)
        {
            var user = await _unitOfWork.CrUserRepository.GetById(cart.IdUser);
            var customer = await _unitOfWork.CrCustomerRepository.GetById(cart.IdCustomer);

            var carts = _unitOfWork.CrCartRepository.GetAllWithNoTracking();
            carts = carts.Where(x => x.IdCustomer == cart.IdCustomer && x.Status == "Saved" && x.IdUser == cart.IdUser);

            if (user == null)
            {
                throw new BusinessException("El usuario introducido no existe");
            }

            if (customer == null)
            {
                throw new BusinessException("El cliente introducido no existe");
            }

            if (carts.Count() >= 1 && cart.Status == "Saved")
            {

                throw new BusinessException("Ya existe un carrito con estado -Saved- asignado al cliente " +
                    customer.Name);
            }

             _unitOfWork.CrCartRepository.Update(cart);
            await _unitOfWork.SaveChangesAsync();

            return true;

        }

public IEnumerable<T> GetAllWithNoTracking()
        {
            return _entities.AsNoTracking().AsEnumerable();
        }

Answer 1

有时，如果您使用async使用没有的实体等待等待的实体，以及您的第一个async任务完成之前，您开始调用另一个任务，将投掷此异常。

因此，此外，您应该使用实体使用asnotracking（）方法，您将不会更改，然后无法保存（只需读取）。

更新1：
在您的代码末尾，请检查以下行：

_unitOfWork.CrCartRepository.Update(cart);
await _unitOfWork.SaveChangesAsync(); 

也许您需要在_unitofwork.crcartrepository.update（cart）;

更新2：

public IEnumerable<T> GetAllWithNoTracking()
{
   return _entities.AsNoTracking().AsEnumerable();
}

public async Task<T?> GetByIdWithNoTracking(int id)
{
    return await _entities.AsNoTracking().FirstOrDefault(x => x.id == id);
}

之前添加等待 。或者，如果您有最新的EF Core，则可以用asnotrackingWithIdentityResolution（）替换它。

更新3
也可以尝试以下操作：

_context.Entry(entity).State = EntityState.Modified;
_context.SaveChanges();