订阅返回未定义的变量

Question

So in general, the shopping cart details are stored in local storage, being parsed back and assinged to an array, and then should be subscribed and posted to MongoDB, but returns "undefined":

checkout.ts

 confirmOrder(){ let orderDetails: any = {}; orderDetails.firstName = this.checkOutForm.controls['firstName'].value; orderDetails.lastName = this.checkOutForm.controls['lastName'].value; orderDetails.phone = this.checkOutForm.controls['phone'].value; orderDetails.address = this.checkOutForm.controls['address'].value; orderDetails.country = this.checkOutForm.controls['country'].value; orderDetails.city = this.checkOutForm.controls['city'].value; this.orderItem=[]; for (let i in this.productAddedToCart) { this.orderItem.push({ product_Name:this.productAddedToCart[i].product_Name, id:this.productAddedToCart[i].id, product_Price:this.productAddedToCart[i].product_Price, product_Quantity:this.productAddedToCart[i].product_Price, type:this.productAddedToCart[i].type, product_Img: this.productAddedToCart[i].product_Img, product_Description:this.productAddedToCart[i].product_Description, _id:this.productAddedToCart[i]._id }); } orderDetails.product= this.orderItem debugger console.log("orderDetails:", orderDetails.product) this.connectionService.sendReceipt(this.checkOutForm.value).subscribe((res) =>{ debugger console.log("res is:", res); }); this.orderService.CreateOrder(orderDetails).subscribe((data:OrderDetails) => { debugger console.log("data is:", data) // prints nothing debugger this.globalResponse = data console.log("data is:", this.globalResponse) //prints nothing debugger }); alert('Your order has been received.'); this.checkOutForm.reset(); this.disabledSubmitButton = true; this.router.navigate(['/']); localStorage.removeItem('product'); localStorage.removeItem('cartItemCount'); };

this.globalResonse is "undefined". Why is it not possible to console.log(data)? Doesnt it get subscribed?

order.service.ts:

 CreateOrder(orderDetails:OrderDetails){ return this.http.post(`${this.uri}/order`, orderDetails,{ observe:'body'}) }

My backend if needed(works):

 //create order orderRoute.route('/').post((req, res) =>{ Product.findById(req.body.productId).populate('product').then(product => { if(.product){ return res.status(404):json({ message; "product not found" }): } const order = new OrderDetails({ _id. new mongoose.Types,ObjectId(): product. req.body,productId: email. req.body,email: firstName.req.body,firstName: lastName. req.body,lastName: phone. req.body,phone: address. req.body,address; }). return order.save() }).then(result => { console;log(result). return res.status(200):json({ message, "Order was Created": order: { order_id. result,_id: product. result,product: firstName.result,firstName: lastName. result,lastName: email. result,email: phone. result,phone: address. result,address: createdAt, new Date, }: request:{ type,"GET": order_url: "http://localhost.5000/order/" + result;_id } }). }).catch(err => { console;log(err). res.status(500):json({ error;err }); }); });

I also receive 2 errors: Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client

(node:17548) UnhandledPromiseRejectionWarning: Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client

Much Appreciated!

Answer 1

I think the reason for not to receive any data from executing CreateOrder() because it get an interesting HTTP error. From following this document I got this content and it says,

Error [ERR_HTTP_HEADERS_SENT] is an interesting error that is fired up when a server tries to send more than one response to a client. What this means is that for a given client request the server previously sent a response (either a success response with the resource requested or error response for a bad request) back to the client and now is unexpectedly trying to send another response

So your backend tries to send the response twice. that's the issue here. If you could open the network tab in the browser console you can inspect if it's true.
Hope this helps.