Can't update custom field value via API

[Mark Dodrill]

I have been trying to update a custom field's value in a Jira Cloud instance via the API, and every time I get a 400 error.  I believe the problem is in how I specify the body of the data to update.  I've done many searches, looked at API docs, and tried to find other examples, but no luck.  I have verified I'm using the correct URL with the correct auth token and have the correct permissions in Jira.

Code is below.  The custom field I'm trying to apply a new value to is a single line text field.  Commented code are all the other ways I've tried to specify the data for the PATCH call, but in all cases they return a 400.  I would appreciate some help since it seems like there is some small thing wrong, but I don't know what it is.

import requests

from requests.auth import HTTPBasicAuth

import json

    url = f"{JIRA_DEST_URL}/rest/api/3/issue/{issue_key}"

    header = {

        "Accept": "application/json",

        "Content-Type": "application/json;odata.metadata=minimal;odata.streaming=true"

    }

    custom_field_id2 = "customfield_10083"

    customfield_value = "Foo"

    #custom_field_preparation = {custom_field_id2: customfield_value}

    #custom_field_preparation = { "update": { custom_field_id2: [ {"set": customfield_value}]}}

    #custom_field_preparation = [{"fields": [{custom_field_id2: { "value": customfield_value}}]}]

    #custom_field_preparation = [{'fields': [{custom_field_id2: { 'value': customfield_value}}]}]

    custom_field_preparation = {

        "fields": {

            custom_field_id2: customfield_value

                }

            }

    response = requests.patch(url,

                            json=custom_field_preparation,

                            headers=header,

                            auth=HTTPBasicAuth(SOURCE_EMAIL, SOURCE_API_TOKEN))

Thanks for the help.

[David Bakkers]

"I've tried to specify the data for the PATCH call"

You might want to try reading the documentation for the Edit Issue endpoint again. That endpoint uses a PUT method, not a PATCH method.