如何使用nodejs和mongodb获取另一个对象内部的对象？

Question

I need to obtain the information contained in the array named detalleInsumos through the _id of that object.

I have tried many ways, but I still have not found the solution to my problem, since it always shows me all the objects of that document, which does not work for me.

This is the document from which I need to get that information:

{
    "_id":{"$oid":"5f9041196462be3c5ca1e53d"},
    "codigoFinca":"000",
    "nombreFinca":"PROVINCIANA",
    "fechaRegistro":"2020-10-21",
    "semanaRegistro":"43",
    "usuarioRegistro":"cotorreo",
    "trabajadoresFinca":[
        {
            "porcentajeRecargo":0,
            "_id":{"$oid":"5f9041196462be3c5ca1e53e"},
            "udpTrabajador":[
                {
                    "unidadesAPagar":null,
                    "valorUnidad":"",
                    "areaLaborada":"2",
                    "semanaNormal":null,
                    "semanaAtrazos":null,
                    "_id":{"$oid":"5f9041196462be3c5ca1e53f"},
                    "detalleInsumos":[
                        {"_id":{"$oid":"5f9041196462be3c5ca1e540"},
                         "codigoInsumo":"20000001",
                         "descripcionInsumo":"NYLON X 5 KILOS",
                         "cantidadAplicada":"153",
                         "idRDI":"426715",
                         "idDetalleSaldo":"24070"
                        }
                    ],
                    "codigoLabor":"101",
                    "nombreLabor":"AMARRE",
                    "loteLaboro":"1"
                }
            ],
            "codigoTrabajador":"0000",
            "nombresTrabajador":"HUMBERTO  MENA MOSQUERA",
            "horasJornada":"10",
            "horasLaboradas":"10"
        }
    ],
    "createdAt":{"$date":"2020-10-21T14:09:29.876Z"},
    "updatedAt":{"$date":"2020-10-21T15:09:51.657Z"},
    "__v":0
}

And this is what I have tried from nodejs:

const consultauno = await Modelo.findOne({
                'trabajadoresFinca.udpTrabajador.detalleInsumos._id': new ObjectId(idInsumo)
            },
            {
                "trabajadoresFinca.udpTrabajador.detalleInsumos": 1
            });
            console.log(consultauno);

Answer 1

You can try,

• $match your condition
• $reduce to iterate loop of trabajadoresFinca array, second $reduce to iterate loop of udpTrabajador array, $filter to get matching object from detalleInsumos array,
• $arrayElemAt will get first object from array when condition match
• $mergeObjects will merge initialValue or reduce and matching object

const consultauno = await Modelo.aggregate([
  {
    $match: {
      "trabajadoresFinca.udpTrabajador.detalleInsumos._id": ObjectId(idInsumo)
    }
  },
  {
    $project: {
      detalleInsumos: {
        $reduce: {
          input: "$trabajadoresFinca",
          initialValue: {},
          in: {
            $mergeObjects: [
              "$$value",
              {
                $reduce: {
                  input: "$$this.udpTrabajador",
                  initialValue: {},
                  in: {
                    $mergeObjects: [
                      "$$value",
                      {
                        $arrayElemAt: [
                          {
                            $filter: {
                              input: "$$this.detalleInsumos",
                              cond: {
                                $eq: ["$$this._id", ObjectId(idInsumo)]
                              }
                            }
                          },
                          0
                        ]
                      }
                    ]
                  }
                }
              }
            ]
          }
        }
      }
    }
  }
])

Playground

---

Second approach, you can use $unwind ,

• $match your conditions
• $unwind deconstruct trabajadoresFinca array
• $unwind deconstruct udpTrabajador array
• $unwind deconstruct detalleInsumos array
• $match your conditions
• $project to show required fields

const consultauno = await Modelo.aggregate([
  {
    $match: {
      "trabajadoresFinca.udpTrabajador.detalleInsumos._id": ObjectId(idInsumo)
    }
  },
  { $unwind: "$trabajadoresFinca" },
  { $unwind: "$trabajadoresFinca.udpTrabajador" },
  { $unwind: "$trabajadoresFinca.udpTrabajador.detalleInsumos" },
  {
    $match: {
      "trabajadoresFinca.udpTrabajador.detalleInsumos._id": ObjectId(idInsumo)
    }
  },
  {
    $project: {
      trabajadoresFinca: "$trabajadoresFinca._id",
      udpTrabajador: "$trabajadoresFinca.udpTrabajador._id",
      detalleInsumos: "$trabajadoresFinca.udpTrabajador.detalleInsumos"
    }
  }
])

Playground