codePost snippet to automatically finalize all submissions of an assignment, and automatically add a comment that sets the grade of the submission

codePost-finalize-all-with-comment.py

import codepost

# variable parameters
# get the API key here: https://codepost.io/settings
API_KEY = "... see above where to get this ..."
COURSE_NAME = "COS126"
COURSE_TERM = "S2022"
ASSIGNMENT = "Programming Exam 1"

# authenticate
codepost.configure_api_key(API_KEY)

# retrieve the course, and then the assignment
# (will crash if the user of the API key doesn't have access to the course)
course = codepost.course.list_available(name=COURSE_NAME, period=COURSE_TERM)[0]
assignment = course.assignments.by_name(name=ASSIGNMENT)

# iterate over all submissions
for submission in assignment.list_submissions():
    
    # claim submission (must assign a grader, here I assign myself)
    submission.grader = "lumbroso@princeton.edu"
    
    # save changes (necessary to be able to assign comments)
    submission.save()
    
    # then select a file on which to add a comment
    test_file = submission.files.by_name(name="TESTS.txt")
    
    # remove all previous comments
    # (to avoid duplicates, if we rerun this process several times)
    for comment in test_file.comments:
        comment.delete()
    
    grade = 30.0 # you could load this from other place
    
    # describe and create the comment
    
    comment = {
        'file': test_file.id,
        'text': (
            "Your final grade is: {} / 30.0\n\n" +
            "Please look at TESTS.txt for a detailed computation."
        ).format(grade),
        'pointDelta': -grade,
        'rubricComment': None,
        'startChar': 0,
        'endChar': 1,    
        'startLine': 1,
        'endLine': 1,    
    }

    codepost.comment.create(**comment)
    
    # finalize the submission
    # (so it is visible to students, once the assignment is "published")
    submission.isFinalized = True
    submission.save()

Read more about this snippet in the corresponding Medium article:
https://medium.com/@jeremie.lumbroso/how-to-automatically-finalize-all-submissions-in-codepost-6650badfeed7