Help with create_expense request using OAUTH2

Hello,

I'm building a personal project of a Vue.JS front-end form to automate some of the settings I typically enter into splitwise.

I'm trying to do OAUTH2 authentication using https://github.com/Bearer/Pizzly . I can use Postman going through the Pizzly proxy (running locally) to do a GET /get_current_user just fine. But when I try to POST to create_expense (through the Pizzly proxy), I receive this error: "You must enter an amount":

Request Log (Postman)

POST http://localhost:8080/proxy/splitwise/create_expense
200
593 ms
POST /proxy/splitwise/create_expense HTTP/1.1
Pizzly-Auth-Id: 64350b70-2cdb-11eb-8198-150293bf7302
Accept: application/json
Content-Type: application/json
User-Agent: PostmanRuntime/7.26.5
Postman-Token: d39504db-0fe7-4996-ace6-fb1fa16eb490
Host: localhost:8080
Accept-Encoding: gzip, deflate, br
Connection: keep-alive
Content-Length: 415
{
    "cost": "1.00",
    "currency_code": "GBP",
    "description": "Niki proxy API from Postman",
    "payment": false,
    "group_id": "11912464",
    "split_equally": true,
    "users__0__user_id": "906803",
    "users__0__paid_share": "0.50",
    "users__0__owed_share": "0.50",
    "users__1__user_id": "6811318",
    "users__1__paid_share": "0.50",
    "users__1__owed_share": "0.50",
    "category_id": 12
}
HTTP/1.1 200 OK
X-Powered-By: Express
strict-transport-security: max-age=3600
Access-Control-Allow-Origin: *
connection: close
server: nginx
date: Sun, 22 Nov 2020 16:15:04 GMT
content-type: application/json; charset=utf-8
transfer-encoding: chunked
vary: Accept-Encoding
x-frame-options: SAMEORIGIN
x-xss-protection: 1; mode=block
x-content-type-options: nosniff
x-download-options: noopen
x-permitted-cross-domain-policies: none
referrer-policy: origin
content-disposition: inline; filename="response.json"
cache-control: no-cache, no-store
pragma: no-cache
expires: Fri, 01 Jan 1990 00:00:00 GMT
etag: W/"049fe9540d9cef1ef3e05a57584a5dd6"
x-request-id: 3dddff68-4c73-475d-a337-bbc399f90b59
x-runtime: 0.073046
via: 1.1 vegur
{"expenses":[],"errors":{"base":["You must enter an amount"]}}

Error:

{
    "expenses": [],
    "errors": {
        "base": [
            "You must enter an amount"
        ]
    }
}

I'm able to do a POST /create_expense with the same body JSON through Postman using the API Bearer token method with no issues.

POST /api/v3.0/create_expense HTTP/1.1
Accept: application/json
Authorization: Bearer <token>
Content-Type: application/json
User-Agent: PostmanRuntime/7.26.5
Postman-Token: 2814eefd-0524-419e-9195-ecf1ff1cdfe3
Host: secure.splitwise.com
Accept-Encoding: gzip, deflate, br
Connection: keep-alive
Content-Length: 401
{
    "cost": "1.00",
    "currency_code": "GBP",
    "description": "Niki test API",
    "payment": false,
    "group_id": "11912464",
    "split_equally": true,
    "users__0__user_id": "906803",
    "users__0__paid_share": "0.50",
    "users__0__owed_share": "0.50",
    "users__1__user_id": "6811318",
    "users__1__paid_share": "0.50",
    "users__1__owed_share": "0.50",
    "category_id": 12
}
HTTP/1.1 200 OK
Connection: keep-alive
Server: nginx
Date: Sun, 22 Nov 2020 16:25:07 GMT
Content-Type: application/json; charset=utf-8
Transfer-Encoding: chunked
Vary: Accept-Encoding
X-Frame-Options: SAMEORIGIN
X-Xss-Protection: 1; mode=block
X-Content-Type-Options: nosniff
X-Download-Options: noopen
X-Permitted-Cross-Domain-Policies: none
Referrer-Policy: origin
Content-Disposition: inline; filename="response.json"
Cache-Control: no-cache, no-store
Pragma: no-cache
Expires: Fri, 01 Jan 1990 00:00:00 GMT
Etag: W/"c0b200032ecde421125af8e48b013e73"
X-Request-Id: dd2cb811-2874-4245-ab3c-2e574bc6d83c
X-Runtime: 0.265095
Strict-Transport-Security: max-age=3600
Content-Encoding: gzip
Via: 1.1 vegur
{"expenses":[<successful expense info>],"errors":{}}

Any ideas on where I can look next?

Thank you, Nik

Hey Nik! Thanks for the details; those made it easy for me to find the server logs for your request 🙂

It looks like Pizzly (or some other part of your code) is accidentally modifying the parameters somehow before sending them to the Splitwise API. Rather than sending a series of key/value pairs, it's sending the entire JSON blob as one big key, with a value of nil. So instead of our server receiving params like this:

{"cost"=>"1.00", "currency_code"=>"GBP", "description"=>"Niki test API", "payment"=>false, "group_id"=>"11912464", "split_equally"=>true, "users__0__user_id"=>"906803", "users__0__paid_share"=>"0.50", "users__0__owed_share"=>"0.50", "users__1__user_id"=>"6811318", "users__1__paid_share"=>"0.50", "users__1__owed_share"=>"0.50", "category_id"=>12}

We're receiving params like this:

{"{\n    \"cost\": \"1.00\",\n    \"currency_code\": \"GBP\",\n    \"description\": \"Niki proxy API from Postman\",\n    \"payment\": false,\n    \"group_id\": \"11912464\",\n    \"split_equally\": true,\n    \"users__0__user_id\": \"906803\",\n    \"users__0__paid_share\": \"0.50\",\n    \"users__0__owed_share\": \"0.50\",\n    \"users__1__user_id\": \"6811318\",\n    \"users__1__paid_share\": \"0.50\",\n    \"users__1__owed_share\": \"0.50\",\n    \"category_id\": 12\n}"=>nil}

Thus our server fails to find a cost parameter, and you get back the error "You must enter an amount".

—

I'm closing this issue since it doesn't appear to be an API issue, but if you continue to have trouble, feel free to reach out to developers@splitwise.com – we'll help as much as we can!

splitwise / api-docs

Help with create_expense request using OAUTH2 #41