python pass querystring parameters to API gateway

Question

I am trying to integrate API gateway with Lambda proxy,

The API server receives the request with these parameters i.e postcode and house

https://api.domain.com/getAddressproxy?postcode=XX2YZ&house=123

However tests from the API gateway to the Lambda proxy does not return values

https://xxxxxxxxxx.execute-api.eu-west-1.amazonaws.com/Test/getaddressproxy?postcode=XX2YZ&house=123

I think the issue is that the lambda function is not passing the query string parameters to the API server.

Any idea how i can pass the query string parameters to the request object?

Code:

from __future__ import print_function

import json
import urllib2
import ssl

print('Loading function')

target_server = "https://api.domain.com"

def lambda_handler(event, context):
    print("Got event\n" + json.dumps(event, indent=2))

    ctx = ssl.create_default_context()
    ctx.check_hostname = False
    ctx.verify_mode = ssl.CERT_NONE

    print("Event here: ")
    print(event['path'])
    print(event["queryStringParameters"])

    req = urllib2.Request(target_server + event['path'])

    if event['body']:
        req.add_data(event['body'])

    # Copy only some headers
    copy_headers = ('Accept', 'Content-Type')

    for h in copy_headers:
        if h in event['headers']:
            req.add_header(h, event['headers'][h])

    out = {}

    try:
        resp = urllib2.urlopen(req, context=ctx)
        out['statusCode'] = resp.getcode()
        out['body'] = resp.read()

    except urllib2.HTTPError as e:

        out['statusCode'] = e.getcode()
        out['body'] = e.read()

    return out

Answer 1

event["queryStringParameters"] is a dictionary if the API Gateway passes one or None if not passed. Convert this to a query string and append to the Request URL.

...
import urllib
...

qs = urllib.urlencode(event["queryStringParameters"] or {})
req = urllib2.Request(
        ''.join(
          (target_server, event['path'], '?', qs)
        )
      )