Python Request Gives 415 Error While Post Data Unless Data = {'key':'value'}

I am doing a straight forward request as follows. import requests def user_transactions(): url = 'https://webapi.coinfloor.co.uk/v2/bist/XBT/GBP/user_transactions/' d

Solution 1:

Yes, data is optional on the python side. The requests library will happily send a empty request to the server, as you can see. If the argument was not optional, the program would crash before sending a request so there would be no status code.

However, the server needs to be able to process the request. If it does not like what you sent for whatever reason, it might send back a 4xx status code, or otherwise not do what you expect.

In this case, it throws an error that the data is in invalid format. How can a empty request be in invalid format? Because the format is specified in a header. If you supply a data argumet requests will send data in urlencoded format, and specify in the header what format the data is in. If the data is empty, the request will be empty but the header will still be there. This site apparently requires the header to specify a data format it knows.

You can solve this in two ways, giving an empty object:

r = requests.post(url, data={}, auth=("some_username", "some_password") )

Or by explicitly specifying the header:

r = requests.post(url, auth=(...), headers={'Content-Type': 'application/x-www-form-urlencoded'})

Side note: You should not be using W3Schools as a source. It is frequently inaccurate and often recommends bad practices.

Solution 2:

I think you are mistaking the documentation of the requests.post function signature with API documentation. It is saying that data is a keyword argument, not that the API optionally takes data.

It depends on the API endpoint you are trying to use. That endpoint must require data to be sent with the request. If you look at the documentation for the API you are using, it will mention what needs to be sent for a valid request.