链式查找聚合 mongoDB 多个集合

Question

大家好，我想问一下。

所以我有 3 个收藏：

1. 品牌：（brandId、brandName 等...）
2. 合作伙伴：（partnerId、partnerName 等...）
3. 合作伙伴关系：（partnersipId、brandId、partnerId 等...）

如您所见，我想通过 partnerId 加入合作伙伴收藏，我已经加入了。但我需要brandName 成为合作收藏中的brandName 字段。我已经尝试过这个查询：

db.getCollection('partner').aggregate([
    {
        $match: { partnerId: 107 }
    },
    {"$lookup":
        {
            "from" : "partnership",
            "localField" : "partnerId",
            "foreignField" : "partnerId",
            "as" : "partnership"
        }
    },
    {"$lookup" :
        {
            "from" : "brand",
            "localField" : "partnership.brandId",
            "foreignField" : "partnership.brandId",
            "as" : "partnership.brand"
        }
    }])

但没有运气:(

预期结果：

{
    partnerId: 107,
    partnerName: 'TEST',
    partnership: [
        {
            partnerId: 107,
            partnershipId: 'd8b674ab-3c3d-4772-b5e8-81b4c0279424',
            brandId: 66
            brandName: 'BrandNameId66'
        },
        {
            partnerId: 107,
            partnershipId: '13246d75-59ed-47c2-82c5-54f73ad25cf0',
            brandId: 77
            brandName: 'BrandNameId77'
        }
    ]
}

当前结果：

{
    partnerId: 107,
    partnerName: 'TEST',
    partnership: {
        brand: [
            {
                brandId: 1,
                brandName: 'BrandNameId1'
            },
            ...
        ]
    }
}

请帮助我。谢谢！

Answer 1

在下次查找之前，您需要先解除合作伙伴关系：

db.getCollection('partner').aggregate([
    {
        $match: { partnerId: 107 }
    },
    {"$lookup":
        {
            "from" : "partnership",
            "localField" : "partnerId",
            "foreignField" : "partnerId",
            "as" : "partnership"
        }
    },
    {$unwind:{path: "$partnership", preserveNullAndEmptyArrays: true}}
    {"$lookup" :
        {
            "from" : "brand",
            "localField" : "partnership.brandId",
            "foreignField" : "partnership.brandId",
            "as" : "partnership.brand"
        }
    }
    {$group:{
      _id:"$_id",
      partnerId:{$min:"$partnerId"},
      partnerName:{$min:"$partnerName"},
      partnership:{$push:"$partnership"}
    }}
])