Python Requests POST to form records incorrect payload (checkboxes)

I am having quite a bit of trouble with getting the correct form data saved to a server via POST with Requests (2.8.1) module.

I have previous code which does exactly what I want it to do: it encodes a bunch of key:value pairs into the correct header:value payload dict format, and successfully POSTS to the URI. I get a 200 response (what I'm looking for) and everything is great.

This is a section of the OLD payload encoding function, with a ton of key:value pairs omitted for brevity.

Note: the checkbox value set could be any sequence of numbers between 1 and 25, I just wrote it as "item in range(1,5)" to illustrate that the list is comprised of int numbers, i.e. [ "", 1, 2, 3, 4, 5,...] or [ "", 2, 7, 5, 1, 25,...] etc.

checkboxList = ["",]
for item in range(1,5):
    checkboxList.append(item)
payload['checkbox[ids][]'] = checkboxList
...
response = request.post(data_url, data=payload)
>> 200 OK!

Here is a print of what the payload dict (checkboxes) looks like before it's sent to the server:

{... "checkbox[ids][]" : [ "", 2, 17, 20, 5], ...}

And when I look on the page with a browser, all the payload information has been correctly recorded (omitted above) AND the checkboxes (shown above) are correct!

Originally, the checkbox values came from an excel file, as did the rest of the information that was put into the payload before being POSTed to the server. However, now I'm retrieving the information from an SQLite db.

Below is the NEW code that records the checkboxes incorrectly. I should note: I do not have access to the server, so I cannot easily tell if it's a server issue, but let's assume it's not the servers fault. I've had this issue previously, but I got it to work with the above code. However, now that I've started to store the values I need in a db, I cannot get the correct checkboxes recorded by the server.

This is what the data from the db column looks like: "12-5-1-22-4" (... I know this isn't great practice for DB mgmt, but I assume this isn't why the POST is recording the wrong data, and I wanted this question to be as closely representational to my code as possible.)

checkList = checkboxesFromDB.split('-')
payload['checkbox[ids][]'] = checkList
...
response = request.post(data_url, data=payload)
>> 200 OK!

When I look at the site with the browser, it records the checkboxes incorrectly. Now, i should note that 3 checkboxes are selected no matter what I pass to payload['checkbox[ids][]']

It's ALWAYS the same 3, incorrect checkboxes, even if I completely omit 'checkbox[ids][]' from the payload dict. Knowing that, we could assume its a server issue. However, the nearly EXACT code from above works (when I grab the info from an excel file).

I've tried the following (with only one value as a test) without getting the correct checkboxes recorded by the server:

payload['checkbox[ids][]'] = '1'
payload['checkbox[ids][]'] = 1
payload['checkbox[ids][]'] = [1]
payload['checkbox[ids][]'] = ["",1]
payload['checkbox[ids][]'] = [1,""]

When uploading images to the same server, I had an encoding issue when retrieving the image BLOB from the db and trying to pass the buffer object directly to Requests as a file, but I fixed this with cStringIO encoding. (It took me forever as I'm really new to programming, and still unsure of syntax, let alone ways to handle this sort of stuff....) I thought I might be having a similar encoding issue, but with the testing and research I've done, I cannot determine either way as I feel like I'm a bit over my head.

I apologize if this is completely NOOB, but I've done extensive research, trying so many different things that I could think of. I tried passing strings, lists, dicts, forcing encoding of lists as utf-8.

The main reason I'm so perplexed is my original code WORKS, and my new code is nearly identical but doesn't. The only real difference I can think of is now my information is coming from a SQLite db (this particular checkbox column is 'TEXT' type)

Can anyone help me, or point me in a new direction I haven't thought of/know of?

Thank you!