请教linq多表左连接问题

[ufo20020427]

我有三个表：productPackageInfo ， storageDetail ， storage
productPackageInfo 是左表，想先left join storageDetail ，接着 storage
写成sql就是
from productPackageInfo
left join storageDetail on productPackageInfo.字段 = storageDetail .字段
left join storage on storageDetail.字段 = storage.字段

由于 storageDetail 与 storage 先 inner join 的话，产生的集合会相当大，因为不想写成
from productPackageInfo
left join
(storageDetail inner join storage) 这样的形式。

以上业务用sql server是没有问题的，但是用linq总提示：未将对象引用设置到对象的实例

代码如下：

            var listStorageStock = (from productPackageInfo in listProductPackageInfo
                                    join storageDetail in db.T_Warehouse_StorageDetail.AsNoTracking()
                                    on productPackageInfo.F_PackageBarcode equals storageDetail.F_PackageBarcode
                                    into joinPackageStorageDetail
                                    from storageDetail in joinPackageStorageDetail.DefaultIfEmpty()
                                    join storage in db.T_Warehouse_Storage.AsNoTracking()
                                    on storageDetail.F_StorageID equals storage.F_ID
                                    into joinStorageInfoDetail
                                    from storage in joinStorageInfoDetail.DefaultIfEmpty()
                                    where storage.F_WarehouseID == warehouseID
                                    && storageType.Contains(storage.F_Type)
                                    select new
                                    {
                                        F_ProductArchiveID = productPackageInfo.F_ProductArchiveID,
                                        F_ProductBarcode = productPackageInfo.F_ProductBarcode,
                                        F_PackageBarcode = productPackageInfo.F_PackageBarcode,
                                        F_BatchNumber = productPackageInfo.F_BatchNumber,
                                        F_PackageDetailQuantity = productPackageInfo.F_PackageDetailQuantity,
                                        F_PackageDetailOutQuantity = productPackageInfo.F_PackageDetailOutQuantity,
                                        F_StoragDetailQuantity = storageDetail == null ? 0 : storageDetail.F_Quantity,
                                        F_StorageID = storage == null ? string.Empty : storage.F_ID,
                                        F_StorageCode = storage == null ? string.Empty : storage.F_Code,
                                        F_StorageIndex = storage == null ? 3 : ( storage.F_Type == StorageType.备货.ToString() ? 1 : 2)
                                    }).ToList();

不知用linq的话，如何写。谢谢！

[EnForGrass]

你为什么要重复join呢？ from productPackageInfo in listProductPackageInfo join storageDetail in db.T_Warehouse_StorageDetail.AsNoTracking() on productPackageInfo.F_PackageBarcode equals storageDetail.F_PackageBarcode into joinPackageStorageDetail from storageDetail in joinPackageStorageDetail.DefaultIfEmpty() join storage in db.T_Warehouse_Storage.AsNoTracking() on storageDetail.F_StorageID equals storage.F_ID into joinStorageInfoDetail from storage in joinStorageInfoDetail.DefaultIfEmpty() where storage.F_WarehouseID == warehouseID

[EnForGrass]

而且select new里面你可以先写一个字段看看，依次添加字段看看是哪个对象为空？

[ufo20020427]

@Chinajiyong 不是重复，第二个storageDetail 是位于from后面，而不是join后面。只是这变量名