Firebase cloud messaging HTTP v1 send error - 400 Client Error: Bad Request for url: https://fcm.googleapis.com/v1/projects/<PROJECT_ID>/messages:send

I try to use Firebase cloud messaging HTTP v1

Here's the Python code which run under Windows

import json
import requests
from google.oauth2.service_account import Credentials
import google.auth.transport.requests

def _get_access_token():
    credentials = Credentials.from_service_account_file(
        'C:/yocto/wenote-notification/send_notification/wenote-206215-firebase-adminsdk-9fpls-a3fdd2934c.json',
        scopes=['https://www.googleapis.com/auth/firebase.messaging']
    )

    request = google.auth.transport.requests.Request()

    credentials.refresh(request)

    access_token = credentials.token

    return access_token

def generate_header():
    return {'Authorization' : 'Bearer ' + _get_access_token(), 'Content-type' : 'application/json'}


# Header    
headers = generate_header()
print(headers)


# Data
string = '{"message":{"token": "cSW75-6OF-w:APA91bE-E6vWucBe8rRijpDLlZGHhyfwoaLJr3R1TZEvieBM-__ZXwXlBS34kUticUN_eSbwvQGTymbmtd7sHT5U9O_v9HePyVn7jnUD9IBdoZZYSQ1CrgxXS1sz9wjAd5pKHIddoKj8", "data": {"sync": false, "sync_device_count": 2}, "fcm_options": {"analytics_label": "wenote_analytics_label"}}}'
request_data = json.loads(string)
print(request_data)


r = requests.post('https://fcm.googleapis.com/v1/projects/wenote-206215/messages:send', headers=headers, json=request_data)

if r.status_code != 200:
    r.raise_for_status()

The message I send to Firebase server is

{
   "message":{
      "token":"cSW75-6OF-w:APA91bE-E6vWucBe8rRijpDLlZGHhyfwoaLJr3R1TZEvieBM-__ZXwXlBS34kUticUN_eSbwvQGTymbmtd7sHT5U9O_v9HePyVn7jnUD9IBdoZZYSQ1CrgxXS1sz9wjAd5pKHIddoKj8",
      "data":{
         "sync":false,
         "sync_device_count":2
      },
      "fcm_options":{
         "analytics_label":"wenote_analytics_label"
      }
   }
}

However, I'm getting the following error

c:\yocto\wenote-notification\send_notification>python a.py
{'Authorization': 'Bearer ya29.c.Ko8BvQdCd-8US-DzQ-AcuTOURlGTQEvJt4mtofaeM08LRIhXBfC4RFN3QzkAcCdnaqI6uJLQlk1YJg67KQOhF8CtNux9t743nq2NN9uoW2mbQiB2y_2fjRUhiIIM7Wz2nt9rDOM4zFIFwKlHtLPXRLa4IGo0Ho-dq8zzVxQH1qPNGqy_ja8WowQCY5ReAQkmAmE', 'Content-type': 'application/json'}
{'message': {'token': 'cSW75-6OF-w:APA91bE-E6vWucBe8rRijpDLlZGHhyfwoaLJr3R1TZEvieBM-__ZXwXlBS34kUticUN_eSbwvQGTymbmtd7sHT5U9O_v9HePyVn7jnUD9IBdoZZYSQ1CrgxXS1sz9wjAd5pKHIddoKj8', 'data': {'sync': False, 'sync_device_count': 2}, 'fcm_options': {'analytics_label': 'wenote_analytics_label'}}}
Traceback (most recent call last):
  File "a.py", line 38, in <module>
    r.raise_for_status()
  File "C:\Python36\lib\site-packages\requests\models.py", line 940, in raise_for_status
    raise HTTPError(http_error_msg, response=self)
requests.exceptions.HTTPError: 400 Client Error: Bad Request for url: https://fcm.googleapis.com/v1/projects/wenote-206215/messages:send

---

Any idea why it is so, and how I can resolve this?

I have check my Firebase cloud messaging console. It is enabled.

This is the way to debug the above problem.

Use

if r.status_code != 200:
    print(r.text)
    r.raise_for_status()

instead of

if r.status_code != 200:
    r.raise_for_status()

We will get the following error

{
  "error": {
    "code": 400,
    "message": "Invalid value at 'message.data[0].value' (TYPE_STRING), false\nInvalid value at 'message.data[1].value' (TYPE_STRING), 2",
    "status": "INVALID_ARGUMENT",
    "details": [
      {
        "@type": "type.googleapis.com/google.rpc.BadRequest",
        "fieldViolations": [
          {
            "field": "message.data[0].value",
            "description": "Invalid value at 'message.data[0].value' (TYPE_STRING), false"
          },
          {
            "field": "message.data[1].value",
            "description": "Invalid value at 'message.data[1].value' (TYPE_STRING), 2"
          }
        ]
      }
    ]
  }
}

---

Look like HTTP v1 is pretty strict on the value type (It need to be String)

Hence, instead of using

string = '{"message":{"token": "cSW75-6OF-w:APA91bE-E6vWucBe8rRijpDLlZGHhyfwoaLJr3R1TZEvieBM-__ZXwXlBS34kUticUN_eSbwvQGTymbmtd7sHT5U9O_v9HePyVn7jnUD9IBdoZZYSQ1CrgxXS1sz9wjAd5pKHIddoKj8", "data": {"sync": false, "sync_device_count": 2}, "fcm_options": {"analytics_label": "wenote_analytics_label"}}}'

We need to use

string = '{"message":{"token": "cSW75-6OF-w:APA91bE-E6vWucBe8rRijpDLlZGHhyfwoaLJr3R1TZEvieBM-__ZXwXlBS34kUticUN_eSbwvQGTymbmtd7sHT5U9O_v9HePyVn7jnUD9IBdoZZYSQ1CrgxXS1sz9wjAd5pKHIddoKj8", "data": {"sync": "false", "sync_device_count": "2"}, "fcm_options": {"analytics_label": "wenote_analytics_label"}}}'