fix: replace djchoices with Django's built-in TextChoices to fix Pyth…

[ktyagiapphelix2u]

Description

Replaces the deprecated djchoices library with Django's built-in models.TextChoices to resolve Python 3.11 compatibility issues.

Why

The djchoices library depends on pkg_resources (from setuptools), which is not available in Python 3.11+ by default. This was causing ModuleNotFoundError: No module named 'pkg_resources' during course-discovery migrations.

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As explained,maintain backward compatibility with existing constant names
Issue
The migration from djchoices to Django's TextChoices changes all constant names from TitleCase to UPPER_CASE:

ProductTypes.Course → ProductTypes.COURSE
ProductTypes.Program → ProductTypes.PROGRAM
UserGoal.ChangeCareers → UserGoal.CHANGE_CAREERS
This will break the references in edx-course-discovery, since those serializers directly rely on the existing choice names.
eg:course_discovery/apps/course_metadata/search_indexes/serializers/program.py
course_discovery/apps/course_metadata/search_indexes/serializers/course_run.py

[ktyagiapphelix2u]

@rgopalrao-sonata-png capitalizing the names (using SCREAMING_SNAKE_CASE) is necessary when migrating from djchoices to Django's built-in TextChoices. Here's why:

Django's TextChoices follows Python's PEP 8 style guide where class constants should be in UPPERCASE with underscores
The official Django documentation shows all TextChoices members in uppercase (e.g., DRAFT, PUBLISHED)

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Changing these values will impact Course Discovery, since the existing choice names are directly referenced there. You will need to migrate the related changes in Course Discovery as well. In this context, backward compatibility should take precedence over PEP 8 standards, to avoid breaking downstream services.

[rgopalrao-sonata-png]

Can you please try this approach
class ProductTypes(models.TextChoices):
COURSE = 'Course', 'Course' # New PEP 8 name
Course = COURSE

[rgopalrao-sonata-png]

from django.db import models

class ProductTypes(models.TextChoices):
# Retain original naming for backward compatibility
Course = 'course', 'Course'
Program = 'program', 'Program'
XBlock = 'xblock', 'XBlock'
XBlockData = 'xblock_data', 'XBlockData'

class UserGoal(models.TextChoices):
# Retain original naming for backward compatibility
ChangeCareers = 'change_careers', 'I want to change careers'
GetPromoted = 'get_promoted', 'I want to get promoted'
ImproveCurrentRole = 'improve_current_role', 'I want to improve at my current role'
Other = 'other', 'Other'

[ktyagiapphelix2u]

I have updated the code, Thanks.

[ktyagiapphelix2u]

Your change will break the migration

The solution is to add the backward compatibility aliases after the class definition, outside the enum that i have implemented

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Please write the test cases to check eg:# tests/test_choices.py
class TestUserGoalChoices(TestCase):
"""Test UserGoal choice field migration."""

def test_choice_values_consistency(self):
    """Ensure choice values remain the same after migration."""
    # Test old format compatibility
    assert UserGoal.CHANGE_CAREERS == ('change_careers', 'I want to change careers')
    assert UserGoal.GET_PROMOTED == ('get_promoted', 'I want to get promoted')
    assert UserGoal.IMPROVE_CURRENT_ROLE == ('improve_current_role', 'I want to improve at my current role')
    assert UserGoal.OTHER == ('other', 'Other')

also below files test cases also
test_utils/factories.py imports UserGoal for factory creation
tests/test_utilities.py uses ProductTypes in utility function tests
taxonomy/models.py uses UserGoal in model definitions

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Please update the code as per the comments as it will impact course discovery and edx-catalog