embedded

              Promise.all(products.map((productName, i) => {
                    const quantity = Number(quantities[i]);
                    return new Promise((resolve, reject) => {
                      const _product = Products.findOne({ label: productName });
                      return _product.exec();
                    })
                    .then((product) => {
                      customer.inventory.push({
                        someData
                      });
                      customer.markModified("inventory");
                      return customer.save()
                    })
                    .then((customer) => {
                      user.sales.push({
                        someData
                      });
                      return user.save();
                    })
                  }))
                .then(() => {
                  res.json({
                    message: "Sales successful",
                    status: true
                  });
                })
                .catch((e) => {
                  res.json({
                    message: "Sales failed to be added",
                    status: false
                  });
                });