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How to do pass a Request Body while doing a 307 Redirect with a( POST Method and body ) from AWS Lambda , in python

I need to redirect to an another end point from my AWS Lambda function.
I have implemented below code in AWS Lambda function and trying to Redirect to an End Point implement in external system as a POST end point. I am not sure how to pass the Request Body.
Python code is trying to redirect, but I am not sure how to pass a "new" Request Body as it is a POST Endpoint, I don't want the original body to get transmitted.
Please see the Java error at the destination where it got redirected.
def lambda_handler(event, context):
# Create Dictionary
value = {
"language": "python33",
"greetings" : "Greetings... Hope you have been redirected"
}
# Dictionary to JSON Object using dumps() method
# Return JSON Object
return {
"headers": {"Location": "http://localhost:8080/urlcallback",'Content-Type':'application/json' ,},
'statusCode': 307,
'body': json.dumps(value)
}
The Redirected End Point is getting invoked, but with the below error in the JAVA Spring boot logs:
{
"timestamp": 1671820676750,
"status": 500,
"error": "Internal Server Error",
"exception": "org.springframework.http.converter.HttpMessageNotReadableException",
"message": "Required request body is missing: public java.util.Map<java.lang.String, java.lang.String> my.sample.service.controller.PingController.urlcallback(java.lang.String)",
"path": "/urlcallback"
}
I will greatly appreciate any suggestions or pointers. I could not find any when I checked on StackOverFlow
Note:
I tried first with basic redirect of 301 and 302, that works for a GET call, but now I get an error while doing a Redirect with POST end point and a request body as I have some sensitive data to transmit

I am not sure how to pass a "new" Request Body as it is a POST Endpoint, I don't want the original body to get transmitted.
Based on HTTP 307 docs this is not possible: "307 guarantees that the method and the body will not be changed when the redirected request is made"
You can try HTTP 303 and change the request type to GET to remove the body from the request.

HTTP Triggering Cloud Function with Cloud Scheduler

I have a problem with a job in the Cloud Scheduler for my cloud function. I created the job with next parameters:
Target: HTTP
URL: my trigger url for cloud function
HTTP method: POST
Body:
{
"expertsender": {
"apiKey": "ExprtSender API key",
"apiAddress": "ExpertSender APIv2 address",
"date": "YYYY-MM-DD",
"entities": [
{
"entity": "Messages"
},
{
"entity": "Activities",
"types":[
"Subscriptions"
]
}
]
},
"bq": {
"project_id": "YOUR GCP PROJECT",
"dataset_id": "YOUR DATASET NAME",
"location": "US"
}
}
The real values has been changed in this body.
When I run this job I got an error. The reason is caused by processing body from POST request.
However, when I take this body and use it as Triggering event in Testing I don't get any errors. So I think, that problem in body representation for my job but I havn't any idea how fix it. I'll be very happy for any idea.

Disclaimer:
I have tried to solve the same issue using NodeJS and I'm able to get a solution
I understand that this is an old question. But I felt like its worth to answer this question as I have spent almost 2 hours figuring out the answer for this issue.
Scenario - 1: Trigger the Cloud Function via Cloud Scheduler
Function fails to read the message in request body.
Scenario - 2: Trigger the Cloud Function via Test tab in Cloud Function interface
Function call always executes fine with no errors.
What did I find?
When the GCF routine is executed via Cloud Scheduler, it sends the header content-type as application/octet-stream. This makes express js unable to parse the data in request body when Cloud scheduler POSTs the data.
But when the exact same request body is used to test the function via the Cloud Function interface, everything works fine because the Testing feature on the interface sends the header content-type as application/json and express js is able to read the request body and parses the data as a JSON object.
Solution
I had to manually parse the request body as JSON (explicitly using if condition based on the content-type header) to get hold of data in the request body.
/**
* Responds to any HTTP request.
*
* #param {!express:Request} req HTTP request context.
* #param {!express:Response} res HTTP response context.
*/
exports.helloWorld = (req, res) => {
let message = req.query.message || req.body.message || 'Hello World!';
console.log('Headers from request: ' + JSON.stringify(req.headers));
let parsedBody;
if(req.header('content-type') === 'application/json') {
console.log('request header content-type is application/json and auto parsing the req body as json');
parsedBody = req.body;
} else {
console.log('request header content-type is NOT application/json and MANUALLY parsing the req body as json');
parsedBody = JSON.parse(req.body);
}
console.log('Message from parsed json body is:' + parsedBody.message);
res.status(200).send(message);
};
It is truly a feature issue which Google has to address and hopefully Google fixes it soon.
Cloud Scheduler - Content Type header issue

Another way to solve the problem is this:
request.get_json(force=True)
It forces the parser to treat the payload as json, ingoring the Mimetype.
Reference to the flask documentation is here
I think this is a bit more concise then the other solutions proposed.

Thank you #Dinesh for pointing towards the request headers as a solution! For all those who still wander and are lost, the code in python 3.7.4:
import json
raw_request_data = request.data
# Luckily it's at least UTF-8 encoded...
string_request_data = raw_request_data.decode("utf-8")
request_json: dict = json.loads(string_request_data)
Totally agree, this is sub-par from a usability perspective. Having the testing utility pass a JSON and the cloud scheduler posting an "application/octet-stream" is incredibly irresponsibly designed.
You should, however, create a request handler, if you want to invoke the function in a different way:
def request_handler(request):
# This works if the request comes in from
# requests.post("cloud-function-etc", json={"key":"value"})
# or if the Cloud Function test was used
request_json = request.get_json()
if request_json:
return request_json
# That's the hard way, i.e. Google Cloud Scheduler sending its JSON payload as octet-stream
if not request_json and request.headers.get("Content-Type") == "application/octet-stream":
raw_request_data = request.data
string_request_data = raw_request_data.decode("utf-8")
request_json: dict = json.loads(string_request_data)
if request_json:
return request_json
# Error code is obviously up to you
else:
return "500"

One of the workarounds that you can use is to provide a header "Content-Type" set to "application/json". You can see a setup here.

Facebook Messenger with Flask

I'm trying to get the FB messenger API working using Python's Flask, adapting the following instructions: https://developers.facebook.com/docs/messenger-platform/quickstart
So far, things have been going pretty well. I have verified my callback and am able to receive the messages I send using Messenger on my page, as in the logs in my heroku server indicate the appropriate packets of data are being received by my server. Right now I'm struggling a bit to send responses to the client messenging my app. In particular, I am not sure how to perform the following segment from the tutorial in Flask:
var token = "<page_access_token>";
function sendTextMessage(sender, text) {
messageData = {
text:text
}
request({
url: 'https://graph.facebook.com/v2.6/me/messages',
qs: {access_token:token},
method: 'POST',
json: {
recipient: {id:sender},
message: messageData,
}
}, function(error, response, body) {
if (error) {
console.log('Error sending message: ', error);
} else if (response.body.error) {
console.log('Error: ', response.body.error);
}
});
}
So far, I have this bit in my server-side Flask module:
#app.route('/', methods=["GET", "POST"])
def chatbot_response():
data = json.loads(req_data)
sender_id = data["entry"][0]["messaging"][0]["sender"]["id"]
url = "https://graph.facebook.com/v2.6/me/messages"
qs_value = {"access_token": TOKEN_OMITTED}
json_response = {"recipient": {"id": sender_id}, "message": "this is a test response message"}
response = ("my response text", 200, {"url": url, "qs": qs_value, "method": "POST", "json": json_response})
return response
However, running this, I find that while I can process what someone send my Page, it does not send a response back (i.e. nothing shows up in the messenger chat box). I'm new to Flask so any help would be greatly appreciated in doing the equivalent of the Javascript bit above in Flask.
Thanks!

This is the code that works for me:
data = json.loads(request.data)['entry'][0]['messaging']
for m in data:
resp_id = m['sender']['id']
resp_mess = {
'recipient': {
'id': resp_id,
},
'message': {
'text': m['message']['text'],
}
}
fb_response = requests.post(FB_MESSAGES_ENDPOINT,
params={"access_token": FB_TOKEN},
data=json.dumps(resp_mess),
headers = {'content-type': 'application/json'})
key differences:
message needs a text key for the actual response message, and you need to add the application/json content-type header.
Without the content-type header you get the The parameter recipient is required error response, and without the text key under message you get the param message must be non-empty error response.

This is the Flask example using fbmq library that works for me:
echo example :
from flask import Flask, request
from fbmq import Page
page = fbmq.Page(PAGE_ACCESS_TOKEN)
#app.route('/webhook', methods=['POST'])
def webhook():
page.handle_webhook(request.get_data(as_text=True))
return "ok"
#page.handle_message
def message_handler(event):
page.send(event.sender_id, event.message_text)

In that scenario in your tutorial, the node.js application is sending an HTTP POST request back to Facebook's servers, which then forwards the content on to the client.
So far, sounds like your Flask app is only receiving (AKA serving) HTTP requests. The reason is that that's what the Flask library is all about, and it's the only thing that Flask does.
To send an HTTP request back to Facebook, you can use any Python HTTP client library you like. There is one called urllib in the standard library, but it's a bit clunky to use... try the Requests library.
Since your request handler is delegating to an outgoing HTTP call, you need to look at the response to this sub-request also, to make sure everything went as planned.
Your handler may end up looking something like
import json
import os
from flask import app, request
# confusingly similar name, keep these straight in your head
import requests
FB_MESSAGES_ENDPOINT = "https://graph.facebook.com/v2.6/me/messages"
# good practice: don't keep secrets in files, one day you'll accidentally
# commit it and push it to github and then you'll be sad. in bash:
# $ export FB_ACCESS_TOKEN=my-secret-fb-token
FB_TOKEN = os.environ['FB_ACCESS_TOKEN']
#app.route('/', method="POST")
def chatbot_response():
data = request.json() # flasks's request object
sender_id = data["entry"][0]["messaging"][0]["sender"]["id"]
send_back_to_fb = {
"recipient": {
"id": sender_id,
},
"message": "this is a test response message"
}
# the big change: use another library to send an HTTP request back to FB
fb_response = requests.post(FB_MESSAGES_ENDPOINT,
params={"access_token": FB_TOKEN},
data=json.dumps(send_back_to_fb))
# handle the response to the subrequest you made
if not fb_response.ok:
# log some useful info for yourself, for debugging
print 'jeepers. %s: %s' % (fb_response.status_code, fb_response.text)
# always return 200 to Facebook's original POST request so they know you
# handled their request
return "OK", 200

When doing responses in Flask, you have to be careful. Simply doing a return statement won't return anything to the requester.
In your case, you might want to look at jsonify(). It will take a Python dictionary and return it to your browser as a JSON object.
from flask import jsonify
return jsonify({"url": url, "qs": qs_value, "method": "POST", "json": json_response})
If you want more control over the responses, like setting codes, take a look at make_response()

AngularJS $http.post and Python CGI FieldStorage

I have a problem with $https.post parameters on AngularJS. I read that AngularJS is creating a JSON for the params.
So I applied the solution found here:
AngularJS - Any way for $http.post to send request parameters instead of JSON?
http://victorblog.com/2012/12/20/make-angularjs-http-service-behave-like-jquery-ajax/
But I still have problem with Python CGI.
[Edit]
Output of the console.log for objData:
Object {hostname: "test", id_venue: 20}
inspecting Request Payload:
action: "insert",
objData: { first: "test", second:"test2" }
[/Edit]
Website call
angular.module('myApp.services', [])
.service('MyService', ['$http', '$q', function ($http, $q) {
this.insert = function (objData){
console.log(objData);
var deferred = $q.defer();
$http.post('api/api.py', { action: 'insert', objData: objData }).success(function (data, status, headers, config) {
deferred.resolve(data);
}).error(function (response) {
deferred.reject("error");
});
return deferred.promise;
};
}])
Server side code is made with Python and CGI. It is unfortunately a constraint that I cannot use web frameworks.
api/api.py
import cgi
params = cgi.FieldStorage()
print 'Content-type: application/json'
print
print params
print params['objData'].value
Inspective the request headers and response, and I have obviously a KeyError:
FieldStorage(None, None, [MiniFieldStorage('action', 'insert'), MiniFieldStorage('objData[first]', 'test'), MiniFieldStorage('objData[second]', 'test2')])
KeyError: 'objData'
Any solution on how to correctly read params on Python CGI FieldStorage.
Or any way to send them correctly with AngularJS?
With $http.get I don't have any problem.
Maybe one solution could be to handle POST request directly in Python without using cgi.FieldStorage.

As far as I can see, on the js side, objData seems to contain {"first": "test", "second": "test2"}.
As a 1st recommendation, I would recommend to make your life easier by using objData keys as POST keys by doing sth like this on the js client side (I'm assuming objData keys don't start with a underscore so that on the server side, you can make a difference between action and obj keys) :
params = {_action:'insert'};
_.extend(params, objData); // using underscore or lodash
[...]
$http.post('api/api.py', params)
The potential problem is that your insert function is quite generic, objData could be anything (so sth else than a js dictionnary), my second recommendation would be to first serialize your objData as a json string (you can find js libs for this), then send {action: 'insert', 'jsondata': json_string}.
On the python side, you will have to deserialize the json_string which is quite easy with json module.
Thus, you can both use a classical POST (<-> not full json encoded form data) and some json stuff.
HTH

$.ajax function : send json data : parse at serverside function

I am using $.ajax function to send json data to serverside function.
var jsonObjects = [{id:1, name:"amit"}, {id:2, name:"ankit"},{id:3,name:"atin"},{id:1, name:"puneet"}];
$.ajax({
url: "{{=URL('myControllerName')}}",
type: "POST",
context: document.body,
data: {students: JSON.stringify(jsonObjects) },
dataType: "json",
success: function(){
alert('ok');
}
});
In the serverside function, how do I access the data?
Somebody has give the code for grails as :---
//this code is written in grails
import grails.converters.JSON;
List<JSON> students = JSON.parse(params.students) //students in request params is parsed to json objects and stored in the List
println "Student id: " + students[0].studentId //first element of the students list is accessed as a map holding a key studentId
I want to do this in a python web framework viz. web2py.
Tried to access it as params.students and request.students, but no luck.
What is the correct syntax to access the data sent? (I checked the jQuery API, but couldn't find the same).
Thanks,
Vineet

You are confused.
"How to access the data on the serverside" has nothing to do with jquery, and everything to do with your server-side web framework.
You need to extract the data from the request object; the web2py documentation for that is here: http://web2py.com/book/default/chapter/04#request