HTTP API Assistance

General Usage
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1

Hello,

I am trying to translate this Python3 script into Julia (https://github.com/Brightspace/bds-headless-client-example/blob/master/main.py) to gain more familiarity with Julia and building an application that relies on an API.

In particular, I am trying to understand the following function:

def trade_in_refresh_token(config):
    # https://tools.ietf.org/html/rfc6749#section-6
    response = requests.post(
        '{}/core/connect/token'.format(config['auth_service']),
        # Content-Type 'application/x-www-form-urlencoded'
        data={
            'grant_type': 'refresh_token',
            'refresh_token': config['refresh_token'],
            'scope': 'datahub:dataexports:*'
        },
        auth=HTTPBasicAuth(config['client_id'], config['client_secret'])
    )

    if response.status_code != 200:
        logger.error('Status code: %s; content: %s', response.status_code, response.text)
        response.raise_for_status()

    return response.json()

Does the HTTP (or any Julia) package have the ability to specify a Dictionary for the grant_type, refresh_token, and scope and has a similiar function to HTTPBasicAuth to parse in the client_id and client_secret?

I have executed the Python3 script without complications, but I have a limited understanding on HTTP post and response functions.

Is there any good documentation about how to make Julia work for the scenario?

Thanks!

2

Looking at the docs for HTTP.jl there is this example:

using JSON
params = Dict("user"=>"RAO...tjN", "token"=>"NzU...Wnp", "message"=>"Hello!")
base_url = "http://api.domain.com"
endpoint = "/1/messages.json"
url = base_url * endpoint
r = HTTP.request("POST", url,
             ["Content-Type" => "application/json"],
             JSON.json(params))
println(JSON.parse(String(r.body)))

The way HTTP works is that HTTP.request(“POST”, url, headers, body) needs the data here (grant type, refresh_token, and scope) passed in as a json string. Json and dictionaries are easy to convert between, so make a dictionary as in this example, and use JSON.json(dict) to turn it into a json string for the body of the request here.

The auth is a bit trickier, but still not too bad. The way HTTP Basic Authentication works can be done in a few steps:

  1. Combine the username and password into a string, separated by a “:”:
plaintext = config["client_id"] * ":" * config["client_secret"]
  1. Convert the string to the base64 encoding of it (and this seems clunky, there’s gotta be a better way):
io = IOBuffer();
iob64_encode = Base64EncodePipe(io);
write(iob64_encode, plaintext);
close(iob64_encode);
encoded = String(take!(io))

3: Prepend that string with "Basic " (note the space):

value = "Basic " * encoded

4: Write a header with the key as “Authorization” and the value as this new string “Basic dXNlcjpwYXNzd29yZA==” (the value here is your “value” above, but this example is the base64 encoding of the string “user:password”)

Updating the example above:

using JSON
params = Dict("user"=>"RAO...tjN", "token"=>"NzU...Wnp", "message"=>"Hello!")
base_url = "http://api.domain.com"
endpoint = "/1/messages.json"
url = base_url * endpoint
r = HTTP.request("POST", url,
            ["Authorization" => value],
             JSON.json(params))
println(JSON.parse(String(r.body)))

Now I haven’t tested this, so it might need some small modifications, but hopefully this helps!

3

To convert from or to a base64 encoded string, you can use the Base64 standard library. It contains a function base64encode.

1 Like
4

I’ve worked with brightspace from julia before, heres what worked for me. https://gist.github.com/tm-schwartz/8db89504d37377d2ca24dc992c12b42f

I know this is kind of an old post, but I found it while trying to figure out how to work wit the api so figured I’d reply in case anyone else comes across it.