Angular resource not returning error response - angularjs

Question

I'm having this trouble of handling error responses in AngularJS while using $resource. My setup works perfectly with status 200 responses, but when the API throws out a 400 error I just get an empty object.
This is my controller:
$scope.createProduct = function() {
Api.product.save($scope.product).$promise.then(
function(res) {
console.log(res);
},
function(error) {
console.log(error);
}
)
}
This is my Api service:
function ApiService($resource, API_URL) {
return {
product: $resource(
API_URL + '/product/:product_id', { 'product_id': '#product_id' },
{
show: { method: 'GET' },
update: { method: 'PUT', headers: {'Content-Type': 'application/json'} },
}
),
}
}
This is what console.log(error) prints out after a 400 error:
Object {data: null, status: -1, config: Object, statusText: ""}
And finally this is the error response API spits out which I don't get:
{
"errors": {
"message": [
"The town field is required.",
"The postcode field is required.",
]
}
}
Any help would be appreciated, thanks!
EDIT: As an example try sending a POST request to https://api.twitter.com/1.1/statuses/destroy/1.json. If I do this on Postman, I get this error message:
{
"errors": [
{
"code": 215,
"message": "Bad Authentication data."
}
]
}
How do I get this response and the string "Bad Authentication data." in Angular? For some reason I can not do this with my current setup.

Answer 1

The issue may relate to interactions between your API server and CORS.
I am running a Flask based API backend that was presenting this same issue. Troubleshooting led me to discovering that my API was performing a TCP RST when receiving the POST request in around 9 out of 10 connections.
Wireshark capture
The Flask server was logging that the response was being sent back correctly.
2018-08-19 13:26:59,104 INFO: 127.0.0.1 - - [19/Aug/2018 13:26:59] "POST /users/test HTTP/1.1" 419]
Cause
The the cause of the issue was rejecting the POST request in the API backend without reading the POST data first. I refactored my API to always read POST data and this solved the problem.
It's not clear to me how CORS effects this situation, however this problem was only seen when making calls through Angular instead of directly to the API.
The following StackOverflow question pointed me in the right direction to solve this.
No response with POST request and Content-Type "application/json" in flask