MongoDb 过滤阵列

Question

数据结构：

[{
  "_id": {
    "$oid": "5f1e91da1d840d673d159e69"
  },
  "product": [
    {
      "_id": "1",
      "name": "FirstWarehouseName1",
      "image": "FirstWarehousePhoto1",
      "manufacturer": "FirstWarehouseProducer1",
      "warehouse": "Warehouse1",
      "price": "32",
      "amount": 344
    },
    {
      "_id": "2",
      "name": "FirstWarehouseName2",
      "image": "FirstWarehousePhoto2",
      "manufacturer": "FirstWarehouseProducer2",
      "warehouse": "Warehouse1",
      "price": "12",
      "amount": 631
    },
    {
      "_id": "3",
      "name": "FirstWarehouseName3",
      "image": "FirstWarehousePhoto3",
      "manufacturer": "FirstWarehouseProducer3",
      "warehouse": "Warehouse1",
      "price": "66",
      "amount": 752
    }
  ],
  "_class": "pl.com.ttsw.intership.product_model.Products"
},{
  "_id": {
    "$oid": "5f1e91da1d840d673d159e6a"
  },
  "product": [
    {
      "_id": "1",
      "name": "SecondWarehouseName1",
      "image": "SecondWarehousePhoto1",
      "manufacturer": "SecondWarehouseProducerName1",
      "warehouse": "Warehouse2",
      "price": "32",
      "amount": 344
    },
    {
      "_id": "2",
      "name": "SecondWarehouseName2",
      "image": "SecondWarehousePhoto2",
      "manufacturer": "SecondWarehouseProducerName2",
      "warehouse": "Warehouse2",
      "price": "12",
      "amount": 631
    },
    {
      "_id": "3",
      "name": "SecondWarehouseName3",
      "image": "SecondWarehousePhoto3",
      "manufacturer": "SecondWarehouseProducerName3",
      "warehouse": "Warehouse2",
      "price": "66",
      "amount": 752
    }
  ],
  "_class": "pl.com.ttsw.intership.product_model.Products"
},{
  "_id": {
    "$oid": "5f1e91db1d840d673d159e6b"
  },
  "product": [
    {
      "_id": "1",
      "name": "ThirdWarehouseName1",
      "image": "ThirdWarehousePhoto1",
      "manufacturer": "ThirdWarehouse1",
      "warehouse": "Warehouse3",
      "price": "44",
      "amount": 123
    },
    {
      "_id": "2",
      "name": "ThirdWarehouseName2",
      "image": "ThirdWarehousePhoto2",
      "manufacturer": "ThirdWarehouse2",
      "warehouse": "Warehouse3",
      "price": "11",
      "amount": 442
    },
    {
      "_id": "3",
      "name": "ThirdWarehouseName3",
      "image": "ThirdWarehousePhoto3",
      "manufacturer": "ThirdWarehouse3",
      "warehouse": "Warehouse3",
      "price": "2",
      "amount": 2213
    }
  ],
  "_class": "pl.com.ttsw.intership.product_model.Products"
}]

IMG

我也这样尝试:

IMG2

ERROR

////////////////////////////////////////// ////////////////// 我需要按名称过滤数组中的数组（仓库中的产品）；如果我没有项目响应是 Array with all products。输出结果 if (search By "Name3")

[{
  "_id": {
    "$oid": "5f1e91da1d840d673d159e69"
  },
  "product": [
    {
      "_id": "3",
      "name": "FirstWarehouseName3",
      "image": "FirstWarehousePhoto3",
      "manufacturer": "FirstWarehouseProducer3",
      "warehouse": "Warehouse1",
      "price": "66",
      "amount": 752
    }
  ]
},{
  "_id": {
    "$oid": "5f1e91da1d840d673d159e6a"
  },
  "product": [
    {
      "_id": "3",
      "name": "SecondWarehouseName3",
      "image": "SecondWarehousePhoto3",
      "manufacturer": "SecondWarehouseProducerName3",
      "warehouse": "Warehouse2",
      "price": "66",
      "amount": 752
    }
  ]
},{
  "_id": {
    "$oid": "5f1e91db1d840d673d159e6b"
  },
  "product": [
    {
      "_id": "3",
      "name": "ThirdWarehouseName3",
      "image": "ThirdWarehousePhoto3",
      "manufacturer": "ThirdWarehouse3",
      "warehouse": "Warehouse3",
      "price": "2",
      "amount": 2213
    }
  ]
}]

各种方法都试过了，还是不行。 //////////////////////////////

Answer 1

你可以做到

[{
    $unwind: {
        path: "$product",
        preserveNullAndEmptyArrays: false
    }
}, {
    $match: {
        "product.name": {
            $regex: "Name3"
        }
    }
}, {
    $group: {
        _id: "$_id",
        product: {
            $push: "$product"
        }
    }
}]

工作Mongo playground

Answer 2

如果只是过滤一个数组中的一个元素，即使只有一个元素匹配，也会返回整个数组，如果不匹配则什么都不返回。因此，您需要使用 $unwind 运算符将数组分成不同的文档，然后才尝试使用 $match.

过滤结果

以下查询可能会解决您的问题:

db.collection.aggregate([
  {"$unwind": "$product"},
  {"$match": {"product.name": "FirstWarehouseName1"}} // replace here with the name you want
])

工作mongoplayground

如果可以的话，只是一个提示：您应该将每个产品存储在不同的文档中，尽管 MongoDB 是无模式的并且允许我们拥有几乎任何格式的文档，请记住每个文档应包含相当于常规关系数据库中一行信息的信息。否则，您将开始遇到这些问题，此外还会遇到性能问题。

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