How to use the REST API to get students from a course?

I wrote some quick perl and python code to get the list of courses from canvas.

I can get user data for a single course like this:

https://canvas.instructure.com/doc/api/v1/courses/$course/users?per_page=250

where $course is my course number in perl.

However, the max number the API will support appears to be 100. So I need to get the first 100 and link to get the next group. The only docs I can find on paging:

https://canvas.instructure.com/doc/api/file.pagination.html

seems to be more for interactive documents. I don't see anything in the JSON coming back that indicates how to get the next bunch. Any help?

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Accepted answers

Chris

Hi @DOVKRUGER,

The pagination info will not be in the JSON, but rather the html response header. In python, if you use the request library, you can use the .link property of the response to get the current and next links Canvas sends. I could send you a function I've made to get all pages of a Canvas API request if you have interest and are using python. If this is part of your perl code, perhaps someone with experience in that language will come in and give a suggestion.

-Chris

All comments

Chris

Hi @DOVKRUGER,

-Chris

matthew_buckett

It's a long time since I've done any perl, but if you're using HTTP::Client (https://metacpan.org/pod/HTTP::Client), then after doing a get() request, you should be able to use the response_headers (https://metacpan.org/pod/HTTP::Client#$client-%3Eresponse_headers) to get the Link URL values.

Some API endpoints still use the `&page=1` parameters which aren't guaranteed to work in the long run, but as a quick fix may allow you to check that your solution is going to work and you're getting the data back you expect.

dgrobani

Here's the Python function I use to return a list from the API:

def get_list(url, r_data=None):
    """ compile a paginated list up to 100 at a time (instead of default 10) and return the entire list """
    r = get(f'{url}{"&" if "?" in url else "?"}per_page=100', r_data)
    paginated = r.json()
    while 'next' in r.links:
        r = get(r.links['next']['url'], r_data)
        paginated.extend(r.json())
    return paginated

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