无法通过Angular使用Create Order API端点

Question

我想创建订单，但是由于订单猫鼬模式中的产品引用，所以无法创建订单，因此在订单服务中要通过什么功能才能创建订单。这是我写的代码

订购api控制器

exports.orders_create_order = (req, res, next) => {
    Product.findById(req.body.productId)
        .then(product => {
            if (!product) {
                return res.status(404).json({
                    message: "Product not found"
                });
            }
            const order = new Order({
                _id: mongoose.Types.ObjectId(),
                quantity: req.body.quantity,
                product: req.body.productId,
                orderDate: req.body.orderDate
            });
            return order.save();
        })
        .then(result => {
            console.log(result);
            res.status(201).json({
                message: "Order stored",
                createdOrder: {
                    _id: result._id,
                    product: result.product,
                    quantity: result.quantity,
                    orderDate: result.orderDate
                }
            });
        })
        .catch(err => {
            console.log(err);
            res.status(500).json({
                error: err
            });
        });
};

order.service.ts

import { Injectable }  from '@angular/core';
import { Http, Headers } from '@angular/http';
import { HttpModule } from '@angular/http';
import { ActivatedRoute } from '@angular/router';
import 'rxjs/add/operator/map';
import { tokenNotExpired } from 'angular2-jwt';

@Injectable()
export class OrderService{
    product:any;
    constructor(
        private http: Http,
        private route: ActivatedRoute) {
    }

    getOrders() {
        let headers = new Headers();
        headers.append('Content-Type', 'application/json');
        return this.http.get('orders', {headers:headers})
            .map(res =>res.json());
    }
    createOrder(product:object) {
        let headers = new Headers();
        headers.append('Content-Type','application/json');
        headers.append('Accept','application/json');
        return this.http.post('orders',product,{headers:headers})
            .map(res => res.json());
    }
} 

创建订单功能

createorder() {
    this.orderservice.createOrder(this.product).subscribe(data=>{
        this.product=data.product;
    });
}

我无法获得订单控制器创建订单所需的服务中传递的功能。订单架构中以产品为参考，并下达了数量和日期。