return array undefined models controllers expressjs mongoose

Question

I have this problem and I can't find the solution I want you to help me find the solution

the problem

I want to checkout all the books I added to the shopping cart

return array undefined

selle.model.js

/// file selle.model.js

const mongoose = require("mongoose");

// create url connect db

const url = "mongodb://localhost:27017/STOREBOOKS";


// create order in insert data
const order = mongoose.model("orders");

exports.getAllOrders = async (idUser) => {
  return await mongoose
    .connect(url, {
      useNewUrlParser: true,
      useUnifiedTopology: true,
    })
    .then(() => {
      return order.arguments([
        {
          $lookup: {
            from: "books",
            localField: "idBook",
            foreignField: "_id",
            as: "books",
          },
        },
        {
          $match: {
            idUser: idUser,
          },
        },
      ]);
    })
    .catch((err) => {
      console.log(err);
    });
};

selle.controller.js

exports.getPageSelle = (request, response, next) => {
  
  modelSelle.getAllOrders(request.session.userId).then((Orders) => {
   
    console.log(Orders);  // undefined
  });
};