在mongoose中聚合函数$ lookup

Question

以下2个系列：门票＆amp;股

tickets
Pharma: HEA00004
TxtDtVts: 21112017
ID_REGROUP: 20003000           Int64
Cip7: 787853                    
Designation: Doliprane           

stocks

ICat_id:20003000                     Int64
art_st0: 4  

和2个架构

var ticketSchema = mongoose.Schema({
      NumVts: Number,
      Pharma: String,  
      TxtDtVts: Number,
      ID_LGN: Number, 
      ID_REGROUPEMENT: Number, 
}); 
 var Ticket = mongoose.model('Ticket', ticketSchema,'tickets');


var stockSchema = mongoose.Schema({
ICat_ID: Number,
art_st0: Number,
});
 var Stock = mongoose.model('Stock', stockSchema,'stocks');

我正在尝试进行“$ lookup”以获得这样的产品库存：

app.get('/join/:pharma/:jour',function(req,res){ 

              var jour = Number(req.params.jour);

            Ticket.aggregate([

          {"$match":{"Pharma": req.params.pharma}},
          {"$match":{"TxtDtVts": jour}},
          { $group : {_id : {Pharma : "$Pharma"}}},

          { $lookup:
        {
          from: "stocks",
          localField: "ID_REGROUP",
          foreignField: "ICat_ID",
          as: "stock"
        }}, ]

            ,function(err, ticket) {
            if (err)
                res.send(err);
                    res.header("Access-Control-Allow-Origin", "*");
                    res.header("Access-Control-Allow-Methods", "GET, POST, DELETE, PUT, OPTIONS");
                    res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");
                    res.json(ticket);
        });        
});

在响应下方，库存字段仍为空

[
    {
        "_id": 
    {
 "Pharma": "HEA00004"
        },

      "stock": []

}
]

为什么查找不适用于此字段？数据类型是否存在问题（int64）？

感谢您提前