feedback.py - Provide feedback for student answers

Imports

These are listed in the order prescribed by PEP 8.

Standard library

import re
import ast
import json
 

Third-party imports

from gluon import current
 

Local imports

None.

Return (True, feedback) if feedback should be computed on the server, instead of the client. This function assumes that the inputs have already been validated.

def is_server_feedback(div_id, course):

Get the information about this question. Per the web2py docs, an assignment in models/db.py makes current.db available.

    query_results = (
        current.db(
            (current.db.questions.name == div_id)
            & (current.db.questions.base_course == current.db.courses.base_course)
            & (current.db.courses.course_name == course)
        )
        .select(current.db.questions.feedback, current.db.courses.login_required)
        .first()
    )
 

check for query_results

    if not query_results:
        return False, None

If feedback is present, decode it.

    feedback = query_results and query_results.questions.feedback
    if feedback is not None:
        feedback = json.loads(feedback)
        return query_results.courses.login_required, feedback
    else:

If feedback isn’t present, use client-side grading.

        return False, None
 
 

Provide feedback for a fill-in-the-blank problem. This should produce identical results to the code in evaluateAnswers in fitb.js.

def fitb_feedback(answer_json, feedback):

Grade based on this feedback. The new format is JSON; the old is comma-separated.

    if answer_json is None:
        return "F"

    try:
        answer = json.loads(answer_json)

Some answers may parse as JSON, but still be in the old format. The new format should always return an array.

        assert isinstance(answer, list)
    except:
        answer = answer_json.split(",")
    displayFeed = []
    isCorrectArray = []

The overall correctness of the entire problem.

    correct = True
    for blank, feedback_for_blank in zip(answer, feedback):
        if not blank:
            isCorrectArray.append(None)
            displayFeed.append("No answer provided.")
            correct = False
        else:

The correctness of this problem depends on if the first item matches.

            is_first_item = True

Check everything but the last answer, which always matches.

            for fb in feedback_for_blank[:-1]:
                if "regex" in fb:
                    if re.search(
                        fb["regex"], blank, re.I if fb["regexFlags"] == "i" else 0
                    ):
                        isCorrectArray.append(is_first_item)
                        if not is_first_item:
                            correct = False
                        displayFeed.append(fb["feedback"])
                        break
                else:
                    assert "number" in fb
                    min_, max_ = fb["number"]
                    try:

Note that literal_eval does not discard leading / trailing spaces, but considers them indentation errors. So, explicitly invoke strip.

                        val = ast.literal_eval(blank.strip())
                        in_range = val >= min_ and val <= max_
                    except Exception:

In case something weird or invalid was parsed (dict, etc.)

                        in_range = False
                    if in_range:
                        isCorrectArray.append(is_first_item)
                        if not is_first_item:
                            correct = False
                        displayFeed.append(fb["feedback"])
                        break
                is_first_item = False

Nothing matched. Use the last feedback.

            else:
                isCorrectArray.append(False)
                correct = False
                displayFeed.append(feedback_for_blank[-1]["feedback"])
 

Note that this isn’t a percentage, but a ratio where 1.0 == all correct.

    percent = (
        isCorrectArray.count(True) / len(isCorrectArray) if len(isCorrectArray) else 0
    )
 

Return grading results to the client for a non-test scenario.

    if current.settings.is_testing:
        res = dict(
            correct=True,
            displayFeed=["Response recorded."] * len(answer),
            isCorrectArray=[True] * len(answer),
            percent=1,
        )
    else:
        res = dict(
            correct=correct,
            displayFeed=displayFeed,
            isCorrectArray=isCorrectArray,
            percent=percent,
        )
    return "T" if correct else "F", res