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Verifying SendGrid's Signed Event Webhook in Django

I am trying to get signed from sengrid Webhook:
https://docs.sendgrid.com/for-developers/tracking-events/getting-started-event-webhook-security-features
from sendgrid.helpers.eventwebhook import EventWebhook, EventWebhookHeader
def is_valid_signature(request):
#event_webhook_signature=request.META['HTTP_X_TWILIO_EMAIL_EVENT_WEBHOOK_SIGNATURE']
#event_webhook_timestamp=request.META['HTTP_X_TWILIO_EMAIL_EVENT_WEBHOOK_TIMESTAMP']
event_webhook = EventWebhook()
key=settings.SENDGRID_HEADER
ec_public_key = event_webhook.convert_public_key_to_ecdsa(key)
text=json.dumps(str(request.body))
return event_webhook.verify_signature(
text,
request.headers[EventWebhookHeader.SIGNATURE],
request.headers[EventWebhookHeader.TIMESTAMP],
ec_public_key
)
When I send test example from sengrid, always return False. I compared keys and all is correct, so, I think that the problem is the sintax of the payload:
"b[{\"email\":\"example#test.com\",\"timestamp\":1648560198,\"smtp-id\":\"\\\\u003c14c5d75ce93.dfd.64b469#ismtpd-555\\\\u003e\",\"event\":\"processed\",\"category\":[\"cat facts\"],\"sg_event_id\":\"G6NRn4zC5sGxoV2Hoz7gpw==\",\"sg_message_id\":\"14c5d75ce93.dfd.64b469.filter0001.16648.5515E0B88.0\"},{other tests},\\r\\n]\\r\\n"

I think the issue is that you are calling:
text = json.dumps(str(request.body))
json.dumps serializes an object to a JSON formatted string, but str(request.body) is already a string.
Try just
text = str(request.body)

I found the solution, my function is now like this:
def is_valid_signature(request):
#event_webhook_signature=request.META['HTTP_X_TWILIO_EMAIL_EVENT_WEBHOOK_SIGNATURE']
#event_webhook_timestamp=request.META['HTTP_X_TWILIO_EMAIL_EVENT_WEBHOOK_TIMESTAMP']
event_webhook = EventWebhook()
key=settings.SENDGRID_HEADER
ec_public_key = event_webhook.convert_public_key_to_ecdsa(key)
return event_webhook.verify_signature(
request.body.decode('latin-1'),
request.headers[EventWebhookHeader.SIGNATURE],
request.headers[EventWebhookHeader.TIMESTAMP],
ec_public_key
)
I had to decode in Latin-1, because we have my codification in UTF-8.
Thanks

( not failing on missing headers , utf8 decoding , types converted to strings)
def flask_verifySendgridSignedWebhook(myrequest , expectedKey ):
try:
if(myrequest.is_json):
sg_verify=EventWebhook()
msgbody=""
#print("JSON FOUND")
if(myrequest.data):
msgbody=myrequest.get_data().decode('utf-8')
##print(msgbody)
if(sg_verify.verify_signature( msgbody , str( myrequest.headers.get(EventWebhookHeader.SIGNATURE)),
str( myrequest.headers.get(EventWebhookHeader.TIMESTAMP)),
sg_verify.convert_public_key_to_ecdsa(expectedKey) )):
return True
else:
#print("NO JSON SENT")
return False
except:
return False

Translation of a PHP Script to Python3 (Django)

I am attempting to convert from scratch the following PHP script into Python for my Django Project:
Note that it is my understanding that this script should handle values sent from a form, sign the data with the Secret_Key, encrypt the data in SHA256 and encode it in Base64
<?php
define ('HMAC_SHA256', 'sha256');
define ('SECRET_KEY', '<REPLACE WITH SECRET KEY>');
function sign ($params) {
return signData(buildDataToSign($params), SECRET_KEY);
}
function signData($data, $secretKey) {
return base64_encode(hash_hmac('sha256', $data, $secretKey, true));
}
function buildDataToSign($params) {
$signedFieldNames = explode(",",$params["signed_field_names"]);
foreach ($signedFieldNames as $field) {
$dataToSign[] = $field . "=" . $params[$field];
}
return commaSeparate($dataToSign);
}
function commaSeparate ($dataToSign) {
return implode(",",$dataToSign);
}
?>
Here is what I have done so far :
def sawb_confirmation(request):
if request.method == "POST":
form = SecureAcceptance(request.POST)
if form.is_valid():
access_key = 'afc10315b6aaxxxxxcfc912xx812b94c'
profile_id = 'E25C4XXX-4622-47E9-9941-1003B7910B3B'
transaction_uuid = str(uuid.uuid4())
signed_field_names = 'access_key,profile_id,transaction_uuid,signed_field_names,unsigned_field_names,signed_date_time,locale,transaction_type,reference_number,amount,currency'
signed_date_time = datetime.datetime.now()
signed_date_time = str(signed_date_time.strftime("20%y-%m-%dT%H:%M:%SZ"))
locale = 'en'
transaction_type = str(form.cleaned_data["transaction_type"])
reference_number = str(form.cleaned_data["reference_number"])
amount = str(form.cleaned_data["amount"])
currency = str(form.cleaned_data["currency"])
# Transform the String into a List
signed_field_names = [x.strip() for x in signed_field_names.split(',')]
# Get Values for each of the fields in the form
values = [access_key, profile_id, transaction_uuid,signed_field_names,'',signed_date_time,locale,transaction_type,reference_number,amount,currency]
# Insert the signedfieldnames in their place in the list (MUST BE KEPT)
values[3] = 'access_key,profile_id,transaction_uuid,signed_field_names,unsigned_field_names,signed_date_time,locale,transaction_type,reference_number,amount,currency'
# Merge the two lists as one
DataToSign = list(map('='.join, zip(signed_field_names, values)))
# Hash Sha-256
API_SECRET = 'bb588d4f96ac491ebd43cceb18xx149b79291f874f1a41fcbf5bc078bb6c8793af2df5ad4b174f80bd5f24a4e4eec6fdabdxxxxxc6c1410db40252deea613e0b976748539294438694ba08xx4ba831d3d850349cacfa445f9706aa57be7f8e61aab0be2288054dbe88ec6200ccd7c72888bcc0aa373f42059ec248d3c86b0f45'
message = '{} {}'.format(DataToSign, API_SECRET)
signature = hmac.new(bytes(API_SECRET , 'latin-1'), msg = bytes(message , 'latin-1'), digestmod = hashlib.sha256).hexdigest().upper()
base64string = base64.b64encode( bytes(signature, "utf-8") )
When printing the variables as they come, I obtain the following :
VALUES : ['afc10315b6aa3b2a8cfc91253812b94c', 'E25C4FE4-4622-47E9-9941-1003B7910B3B', '0b59b0ae-bd25-4421-a231-bb83dcfc91fa', 'access_key,profile_id,transaction_uuid,signed_field_names,unsigned_field_names,signed_date_time,locale,transaction_type,reference_number,amount,currency', '', '2021-03-06T22:07:30Z', 'en', 'authorization', '1615068450109', '100', 'USD']
DATATOSIGN : ['access_key=afc10315b6aa3b2a8cfc91253812b94c', 'profile_id=E25C4FE4-4622-47E9-9941-1003B7910B3B', 'transaction_uuid=0b59b0ae-bd25-4421-a231-bb83dcfc91fa', 'signed_field_names=access_key,profile_id,transaction_uuid,signed_field_names,unsigned_field_names,signed_date_time,locale,transaction_type,reference_number,amount,currency', 'unsigned_field_names=', 'signed_date_time=2021-03-06T22:07:30Z', 'locale=en', 'transaction_type=authorization', 'reference_number=1615068450109', 'amount=100', 'currency=USD']
SIGNATURE : 953C786EB9884CEC13C24118B00125BDCFE23AFF8AB02E7BEF29A83156C55C16
BASE64STRING : b'OTUzQzc4NkVCOTg4NENFQzEzQzI0MTE4QjAwMTI1QkRDRkUyM0FGRjhBQjAyRTdCRUYyOUE4MzE1NkM1NUMxNg=='
I think I am getting pretty close from the final result I would like to achieve since I would then simply have to post the Base64String to a specific URL.
However, I am unsure of a couple of things which may seem a bit off :
Is my "translation" of the PHP code into Python correct? Am I meant to merge my lists with a result in "DATATOSIGN"? I am not proficient in PHP so I might have misunderstood how to present the data.
The signature in Base64 should be 44 chars AT ALL TIME like "WrXOhTzhBjYMZROwiCug2My3jiZHOqATimcz5EBA07M=" when using the PHP Sample Code but mine way exceeds this limitation.
If you need any additional information, please do not hesitate to ask.
Hope you can give me pointers !

To approach this problem, it might be good to get an idea of what your final PHP result would be for given parameters.
Here are the parameters I'm using for this with your given PHP code:
$params = [
'access_key' => 'afc10315b6aaxxxxxcfc912xx812b94c',
'profile_id' => 'E25C4XXX-4622-47E9-9941-1003B7910B3B',
'transaction_uuid' => '12345',
'signed_field_names' => 'access_key,profile_id,transaction_uuid,signed_field_names,unsigned_field_names,signed_date_time,locale,transaction_type,reference_number,amount,currency',
'unsigned_field_names' => '',
'signed_date_time' => '2021-03-06 16:14:00',
'locale' => 'en',
'transaction_type' => 'credit',
'reference_number' => '12345',
'amount' => '50',
'currency' => 'usd'
];
When I run the original PHP code with these parameters, and these lines for outputting the code:
<?php
echo "build data to sign:\n";
print_r(buildDataToSign($params));
echo "\n";
echo "sign data:\n";
echo signData(buildDataToSign($params), 'secret');
?>
I get the following output:
build data to sign:
access_key=afc10315b6aaxxxxxcfc912xx812b94c,profile_id=E25C4XXX-4622-47E9-9941-1003B7910B3B,transaction_uuid=12345,signed_field_names=access_key,profile_id,transaction_uuid,signed_field_names,unsigned_field_names,signed_date_time,locale,transaction_type,reference_number,amount,currency,unsigned_field_names=,signed_date_time=2021-03-06 16:14:00,locale=en,transaction_type=credit,reference_number=12345,amount=50,currency=usd
sign data:
6V0iIqu3smGmadPK4KvRuHm1nNkuIVLBPbLg7VkA7M8=
So with your new Python version of this PHP code, you'll probably want to have a similar sign data value of 6V0iIqu3smGmadPK4KvRuHm1nNkuIVLBPbLg7VkA7M8= at the end with these parameters!
Because your Python example does not seem to get the same result as-is, after adding a return base64string to the end of your Python def, I get the following output:
sign_data:
b'NThFMjU4QTQyRjU2MkVDRDgzM0RCOEIwM0VDODczQTExNjc3MUNDMEM2OURGMDFGMjdFQkU3MEMzMDAyNjA3RQ=='
In order to match the PHP version of your code, I wanted to try to find out what was going on between the PHP and Python approaches in regard to the hmac and base64 parts.
When I broke down your PHP code example into steps relating to the hmac value and then later the base64 value, here is what I found (using a data message of 'hello' and a key of 'secret' to keep it simple):
Example PHP Code:
<?php
$hash_value = hash_hmac('sha256', 'hello', 'secret', true);
$base64_value = base64_encode($hash_value);
echo "hash value:\n";
echo $hash_value;
echo "\n";
echo "base64 value:\n";
echo $base64_value;
echo "\n";
?>
Example PHP Code Output:
;▒▒▒▒▒C▒|
base64 value:
iKqz7ejTrflNJquQ07r9SiCDBww7zOnAFO4EpEOEfAs=
That looks like some crazy binary-type data! Then, I wanted to try to make sure that the base64 value could be reproduced in Python. To do that, I used a simple approach in Python using the same values as earlier.
Example Python Code:
import base64
import hashlib
import hmac
# Based on your Python code example
hash_value = hmac.new(bytes('secret' , 'latin-1'), msg = bytes('hello', 'latin-1'), digestmod = hashlib.sha256).hexdigest().upper()
base64_value = base64.b64encode(bytes(hash_value, 'utf-8'))
print("hash value:")
print(hash_value)
print("base64 value:")
print(base64_value)
Example Python Code Output:
hash value:
88AAB3EDE8D3ADF94D26AB90D3BAFD4A2083070C3BCCE9C014EE04A443847C0B
base64 value:
b'ODhBQUIzRURFOEQzQURGOTREMjZBQjkwRDNCQUZENEEyMDgzMDcwQzNCQ0NFOUMwMTRFRTA0QTQ0Mzg0N0MwQg=='
So, like you found out earlier, something is causing this base64 value result on the Python side to be longer than the PHP version.
After looking into things more (especially seeing the strange data result in the PHP test code above), I found out that the hash_hmac() function in PHP has the option to return a result in binary form (with the true value at the end of the hash_hmac() in your PHP code example). On the Python side, it looks like you decided to use hmac.hexdigest() which I think I've used before in the past when I wanted a string-like value. For this case, however, I think you might want to get the value back as a binary value. To do this, it looks like you'll want to use hmac.digest() instead.
Modified Example Python Code:
import base64
import hashlib
import hmac
# Based on your Python code example
hash_value = hmac.new(bytes('secret' , 'latin-1'), msg = bytes('hello', 'latin-1'), digestmod = hashlib.sha256).digest()
base64_value = base64.b64encode(bytes(hash_value))
print("hash value:")
print(hash_value)
print("base64 value:")
print(base64_value)
Modified Example Python Code Output:
hash value:
b'\x88\xaa\xb3\xed\xe8\xd3\xad\xf9M&\xab\x90\xd3\xba\xfdJ \x83\x07\x0c;\xcc\xe9\xc0\x14\xee\x04\xa4C\x84|\x0b'
base64 value:
b'iKqz7ejTrflNJquQ07r9SiCDBww7zOnAFO4EpEOEfAs='
Now, the final base64 results appear to match between the example PHP and Python code.
In order for me to better understand what was different between the PHP and Python code, I ended up writing a simple translation of your PHP code into Python (and partly based on your Python code as well).
Here is what the related Python code looks like on my side (with example params):
import base64
import hmac
params = {
'access_key': 'afc10315b6aaxxxxxcfc912xx812b94c',
'profile_id': 'E25C4XXX-4622-47E9-9941-1003B7910B3B',
'transaction_uuid': "12345",
'signed_field_names': 'access_key,profile_id,transaction_uuid,signed_field_names,unsigned_field_names,signed_date_time,locale,transaction_type,reference_number,amount,currency',
'unsigned_field_names': '',
'signed_date_time': "2021-03-06 16:14:00",
'locale': 'en',
'transaction_type': "credit",
'reference_number': "12345",
'amount': "50",
'currency': "usd"
}
SECRET_KEY = 'secret'
def sign(params):
return sign_data(build_data_to_sign(params), SECRET_KEY)
def sign_data(data, secret_key):
return base64.b64encode(bytes(hmac.new(bytes(secret_key, 'latin-1'), msg=bytes(data, 'latin-1'), digestmod='sha256').digest()))
def build_data_to_sign(params):
data_to_sign = []
signed_field_names = params['signed_field_names'].split(',')
for field in signed_field_names:
data_to_sign.append(field + "=" + params[field])
return comma_separate(data_to_sign)
def comma_separate(data_to_sign):
return ','.join(data_to_sign)
When I use my code translation to check your Python code, I checked the values for the variables signed_field_names and DataToSign in your code, and I got the following results:
signed_field_names:
['access_key', 'profile_id', 'transaction_uuid', 'signed_field_names', 'unsigned_field_names', 'signed_date_time', 'locale', 'transaction_type', 'reference_number', 'amount', 'currency']
DataToSign:
['access_key=afc10315b6aaxxxxxcfc912xx812b94c', 'profile_id=E25C4XXX-4622-47E9-9941-1003B7910B3B', 'transaction_uuid=12345', 'signed_field_names=access_key,profile_id,transaction_uuid,signed_field_names,unsigned_field_names,signed_date_time,locale,transaction_type,reference_number,amount,currency', 'unsigned_field_names=', 'signed_date_time=2021-03-06 16:14:00', 'locale=en', 'transaction_type=credit', 'reference_number=12345', 'amount=50', 'currency=usd']
When I check the values with my code translation attempt, I get these values:
signed_field_names:
['access_key', 'profile_id', 'transaction_uuid', 'signed_field_names', 'unsigned_field_names', 'signed_date_time', 'locale', 'transaction_type', 'reference_number', 'amount', 'currency']
DataToSign:
access_key=afc10315b6aaxxxxxcfc912xx812b94c,profile_id=E25C4XXX-4622-47E9-9941-1003B7910B3B,transaction_uuid=12345,signed_field_names=access_key,profile_id,transaction_uuid,signed_field_names,unsigned_field_names,signed_date_time,locale,transaction_type,reference_number,amount,currency,unsigned_field_names=,signed_date_time=2021-03-06 16:14:00,locale=en,transaction_type=credit,reference_number=12345,amount=50,currency=usd
So it looks like your DataToSign = list(map('='.join, zip(signed_field_names, values))) line is specifying a list whereas my code attempt is specifying a string based on your original PHP example.
Because of this, I think you'll want to turn the result back into a string like this (though the variable name could also be written differently if you so choose):
DataToSignString = ','.join(DataToSign)
To save time in this long post, I also found that your message variable was different than my translation of your PHP code. To work around this, I made the message variable in your Python code set to the previously mentioned DataToSignString:
# Commenting out previous message line for now
# message = '{} {}'.format(DataToSignString, API_SECRET)
message = DataToSignString
Also, the following changes seem to be needed for your Python example:
signature = hmac.new(bytes(API_SECRET , 'latin-1'), msg = bytes(message , 'latin-1'), digestmod = hashlib.sha256).digest()
base64string = base64.b64encode(bytes(signature))
This way, you have a binary version of the hmac object. Also, it looks like the utf-8 part might not be needed for now in the base64encode part.
Finally, I added a return to return the calculated base64string while also converting it to a string before base64string is returned:
return str(base64string, 'utf-8')
When put together, here is what the modified code from your Python example looks like:
import base64
import datetime
import hashlib
import hmac
import pprint
import uuid
def sign():
access_key = 'afc10315b6aaxxxxxcfc912xx812b94c'
profile_id = 'E25C4XXX-4622-47E9-9941-1003B7910B3B'
transaction_uuid = "12345"
signed_field_names = 'access_key,profile_id,transaction_uuid,signed_field_names,unsigned_field_names,signed_date_time,locale,transaction_type,reference_number,amount,currency'
signed_date_time = "2021-03-06 16:14:00"
locale = 'en'
transaction_type = "credit"
reference_number = "12345"
amount = "50"
currency = "usd"
# Transform the String into a List
signed_field_names = [x.strip() for x in signed_field_names.split(',')]
# Get Values for each of the fields in the form
values = [access_key, profile_id, transaction_uuid,signed_field_names,'',signed_date_time,locale,transaction_type,reference_number,amount,currency]
# Insert the signedfieldnames in their place in the list (MUST BE KEPT)
values[3] = 'access_key,profile_id,transaction_uuid,signed_field_names,unsigned_field_names,signed_date_time,locale,transaction_type,reference_number,amount,currency'
# Merge the two lists as one
DataToSign = list(map('='.join, zip(signed_field_names, values)))
DataToSignString = ','.join(DataToSign)
# Hash Sha-256
API_SECRET = 'secret'
message = DataToSignString
signature = hmac.new(bytes(API_SECRET , 'latin-1'), msg = bytes(message , 'latin-1'), digestmod = hashlib.sha256).digest()
base64string = base64.b64encode(bytes(signature))
return str(base64string, 'utf-8')
result = sign()
print("sign_data:")
print(result)
The output for this code (with the given parameters) is:
sign_data:
6V0iIqu3smGmadPK4KvRuHm1nNkuIVLBPbLg7VkA7M8=
The value part of this output should be the same as the PHP output from earlier in this post. The earlier value was 6V0iIqu3smGmadPK4KvRuHm1nNkuIVLBPbLg7VkA7M8= and the latest output showed a result of 6V0iIqu3smGmadPK4KvRuHm1nNkuIVLBPbLg7VkA7M8=.

#summea You are god sent ! Thanks a ton ! I cannot believe how much of an effort you made, I am baffled !
If anyone is attempted to Implement Secure Acceptance / CyberSource and see this message, note that you would not be able to pass value="{{ signed_field_names }} in your front end as it is since the data looks like ['access_key','profile_id'].
You would need to either tweak it before sending it (which somehow gives out a Signature Mismatched on CYBS end) or simply hardcode the input field in payment_confirmation like so : value="access_key,profile_id,transaction_uuid,signed_field_names,unsigned_field_names,signed_date_time,locale,transaction_type,reference_number,amount,currency"/>

How to decode examples in Tensorflow 2 (porting from 1.12)

I have the following method which is supposed to decode samples from serialized TFRecordDataset:
def decode_example(self, serialized_example):
"""Return a dict of Tensors from a serialized tensorflow.Example."""
data_fields, data_items_to_decoders = self.example_reading_spec()
# Necessary to rejoin examples in the correct order with the Cloud ML Engine
# batch prediction API.
data_fields['batch_prediction_key'] = tf.io.FixedLenFeature([1], tf.int64, 0)
if data_items_to_decoders is None:
data_items_to_decoders = {
field: tf.contrib.slim.tfexample_decoder.Tensor(field)
for field in data_fields
}
decoder = tf.contrib.slim.tfexample_decoder.TFExampleDecoder(data_fields, data_items_to_decoders)
decode_items = list(sorted(data_items_to_decoders))
decoded = decoder.decode(serialized_example, items=decode_items)
return dict(zip(decode_items, decoded))
However, this does not work under Tensorflow 2.
tf.contrib does not exist anymore and I do not find anything I can use to decode these examples.
I cannot even find the TFExampleDecoder after installing tensorflow-data-validation.
Any idea what's wrong there and/or how I can decode my examples?

I was able to make it work using tf.io.parse_single_example.
We have to declare our data fields as usual (example_reading_spec) which we then can use to decode an example:
def example_reading_spec():
data_fields = {
'inputs': tf.io.VarLenFeature(tf.float32),
'targets': tf.io.VarLenFeature(tf.int64),
}
return data_fields
def decode_example(serialized_example):
"""Return a dict of Tensors from a serialized tensorflow.Example."""
return tf.io.parse_single_example(
serialized_example,
features=example_reading_spec()
)
Now we can use Dataset.map to load our dataset shards like this:
record_dataset = tf.data.TFRecordDataset(filenames, buffer_size=1024)
record_dataset = record_dataset.map(decode_example)

Why am I getting a Runtime.MarshalError when using this code in Zapier?

The following code is giving me:
Runtime.MarshalError: Unable to marshal response: {'Yes'} is not JSON serializable
from calendar import monthrange
def time_remaining_less_than_fourteen(year, month, day):
a_year = int(input['year'])
b_month = int(input['month'])
c_day = int(input['day'])
days_in_month = monthrange(int(a_year), int(b_month))[1]
time_remaining = ""
if (days_in_month - c_day) < 14:
time_remaining = "No"
return time_remaining
else:
time_remaining = "Yes"
return time_remaining
output = {time_remaining_less_than_fourteen((input['year']), (input['month']), (input['day']))}
#print(output)
When I remove {...} it then throws: 'unicode' object has no attribute 'copy'

I encountered this issue when working with lambda transformation blueprint kinesis-firehose-process-record-python for Kinesis Firehose which led me here. Thus I will post a solution to anyone who also finds this questions when having issues with the lambda.
The blueprint is:
from __future__ import print_function
import base64
print('Loading function')
def lambda_handler(event, context):
output = []
for record in event['records']:
print(record['recordId'])
payload = base64.b64decode(record['data'])
# Do custom processing on the payload here
output_record = {
'recordId': record['recordId'],
'result': 'Ok',
'data': base64.b64encode(payload)
}
output.append(output_record)
print('Successfully processed {} records.'.format(len(event['records'])))
return {'records': output}
The thing to note is that the Firehose lambda blueprints for python provided by AWS are for Python 2.7, and they don't work with Python 3. The reason is that in Python 3, strings and byte arrays are different.
The key change to make it work with lambda powered by Python 3.x runtime was:
changing
'data': base64.b64encode(payload)
into
'data': base64.b64encode(payload).decode("utf-8")
Otherwise, the lambda had an error due to inability to serialize JSON with byte array returned from base64.b64encode.

David here, from the Zapier Platform team.
Per the docs:
output: A dictionary or list of dictionaries that will be the "return value" of this code. You can explicitly return early if you like. This must be JSON serializable!
In your case, output is a set:
>>> output = {'Yes'}
>>> type(output)
<class 'set'>
>>> json.dumps(output)
Object of type set is not JSON serializable
To be serializable, you need a dict (which has keys and values). Change your last line to include a key and it'll work like you expect:
# \ here /
output = {'result': time_remaining_less_than_fourteen((input['year']), (input['month']), (input['day']))}

How to iterate over a bytes object in Python?

I am doing a POST request in Django and I am receiving a bytes object. I need to count the number of times a particular user appears on this object but I am receiving the following error TypeError: 'int' object is not subscriptable. This is what I have so far:
def filter_url(user):
''' do the POST request, this code works '''
filters = {"filter": {
"filters": [{
"field": "Issue_Status",
"operator": "neq",
"value": "Queued"
}],
"logic": "and"}}
url = "http://10.61.202.98:8081/Dev/api/rows/cat/tickets?"
response = requests.post(url, json=filters)
return response
def request_count():
'''This code requests a POST method and then it stores the result of all the data
for user001 as a bytes object in the response variable. Afterwards, a call to the
perform_count function is made to count the number of times that user user001 appeared.'''
user = "user001"
response = filter_url(user).text.encode('utf-8')
weeks_of_data = []
weeks_of_data.append(perform_count(response))
def perform_count(response):
''' This code does not work, int object is not subscriptable '''
return Counter([k['user_id'] for k in response)
#structure of the bytes object
b'[{"id":1018002,"user_id":"user001","registered_first_time":"Yes", ...}]'
# This is the result that indicates that response is a bytes object.
print(type(response))
<class 'bytes'>
How can I count the number of times that user001 appears by using the the peform_count() function? Which modification does this function require to work?

You do receive bytes, yes, but you then have the requests library decode it (via the response.text attribute, which automatically decodes the data), which you then re-encode yourself:
response = filter_url(user).text.encode('utf-8')
Apart from just using the response.content attribute instead to avoid the decode -> encode round-trip, you should really just decode the data as JSON:
data = filter_url(user).json()
Now data is a list of dictionaries, and your perform_count() function can operate on that directly.