Question

我有一个以IQueryable

形式获取数据的查询

        var assys = assetrelationshipRepository.GetAll()
            .Where(x => x.AssetId == siteAssetId)
            .Where(x => x.RelationshipTypeId == (long)AssetRelationshipTypeEnum.Parent)
            .Where(x => x.RelatedAsset.AssetTypeId == (long)AssetTypeEnum.Assembly)
            .Select(x => x.RelatedAsset.CustomAssetAttributes2);

对于返回的每个'assy'，我想得到它的AssetId并用它来获取'subassys'列表，见下文。对于每个'assy'记录，assyId变量应替换其AssetId。

        var subassys = assetrelationshipRepository.GetAll()
            .Where(x => x.AssetId == assyId)
            .Where(x => x.RelationshipTypeId == (long)AssetRelationshipTypeEnum.Parent)
            .Where(x => x.RelatedAsset.AssetTypeId == (long)AssetTypeEnum.SubAssy)
            .Select(x => x.RelatedAsset.CustomAssetAttributes2);

我认为我需要使用ForEach，有没有人知道我想做什么是可能的？

由于

Answer 1

应用ForEach将是一种非常糟糕的方法来检索您想要的结果。您可以为该查询应用join和group。

var assysQuery = assetrelationshipRepository.GetAll()
            .Where(x => x.AssetId == siteAssetId)
            .Where(x => x.RelationshipTypeId == (long)AssetRelationshipTypeEnum.Parent)
            .Where(x => x.RelatedAsset.AssetTypeId == (long)AssetTypeEnum.Assembly);

然后应用join和group;

var subAssysQuery = 
            from assy in assysQuery
            join subAssy in assetrelationshipRepository.GetAll() on assy.Id equals subAssy.AssetId
            where 
            subAssy.RelationshipTypeId == (long)AssetRelationshipTypeEnum.Parent &&
            subAssy.RelatedAsset.AssetTypeId == (long)AssetTypeEnum.Assembly
            group assy by assy.Id into g
            select new
            {
              AssyId = g.Key,
              SubAssets = g.Select(x => x.RelatedAsset.CustomAssetAttributes2),
            };

对于每CustomAssetAttributes2条记录，此值应为subassys {。}}。

注意：另外，我建议您使用select子句的已知类型匿名类型。

Linq查询使用另一个查询的结果

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