Django Admin Template Filter Issue

Based on your error message, you're encountering a template syntax error with the length_is filter in your Django 5.1.1 project deployed on Heroku. This issue appears to be related to the Jazzmin admin theme package you're using.

The Problem

The error indicates that Django cannot find the length_is template filter when rendering the admin interface:

TemplateSyntaxError: Invalid filter: 'length_is'

Likely Cause

This error is occurring because the length_is template filter is not available in your Heroku environment. The filter is part of Django's built-in template filters, but it appears that something in your deployment configuration is preventing it from being recognized.

Possible Solutions

1. Check your INSTALLED_APPS configuration:
   Make sure that django.contrib.admin is properly included in your INSTALLED_APPS setting.

2. Verify template settings:
   Ensure your TEMPLATES setting includes the Django template backend with the proper context processors:

   PYTHONCopied
   TEMPLATES = [
       {
           'BACKEND': 'django.template.backends.django.DjangoTemplates',
           'APP_DIRS': True,
           'OPTIONS': {
               'context_processors': [
                   'django.template.context_processors.debug',
                   'django.template.context_processors.request',
                   'django.contrib.auth.context_processors.auth',
                   'django.contrib.messages.context_processors.messages',
               ],
               'libraries': {
                   # You might need to add custom template tags/filters here
               },
           },
       },
   ]

3. Jazzmin compatibility issue:
   Check if your Jazzmin package version is compatible with Django 5.1.1. You might need to update the package or use a version that's compatible with Django 5.1.

4. Collectstatic:
   Make sure you've run python manage.py collectstatic before deploying to Heroku.

5. Check for custom template overrides:
   If you've overridden any admin templates, ensure they're using template filters correctly.

6. Temporary workaround:
   You could try creating a custom template filter that replicates the functionality of length_is and include it in your project.

Since this issue only appears in your Heroku deployment and not locally, it suggests there might be environment-specific differences. Double-check your requirements.txt file to ensure all dependencies are properly specified and that Heroku is installing the correct versions.