部署在Heroku的Django应用帖子不显示，本地正常求排查解决方法

Hey there! Let's break down how to troubleshoot and fix that frustrating issue where your Django Girls blog posts aren't showing up on Heroku—even though everything works perfectly locally and you've pushed all your files correctly.

Start with these checks to pinpoint what's going wrong:

• Check Heroku's real-time logs: This is your first stop for debugging. Run heroku logs --tail in your terminal to see live error messages or warnings. Look for issues like database connection failures, missing migrations, or static file errors.
• Verify database migrations were applied on Heroku: Just because you ran python manage.py migrate locally doesn't mean Heroku knows about it. Run heroku run python manage.py migrate to ensure all your database schema changes are applied to Heroku's PostgreSQL database.
• Double-check environment variables:
  • Is DEBUG set to False on Heroku? If so, static files might not be served correctly. You can temporarily set it to True (only for debugging!) with heroku config:set DEBUG=True to see detailed error pages.
  • Confirm the DATABASE_URL variable exists and is valid—Heroku sets this automatically for PostgreSQL, but it's worth checking with heroku config.
• Validate static file collection: In production, Django needs to collect all static files into a single directory. Run heroku run python manage.py collectstatic --noinput to make sure this step was completed. Also, check that STATIC_ROOT is properly defined in your settings.py (it should point to a folder like staticfiles in your project root).
• Check if data exists in Heroku's database: Use heroku run python manage.py shell to open a Django shell on Heroku. Then run something like from blog.models import Post; print(Post.objects.all()) to see if any posts are stored. If there are none, your local data didn't transfer over, or you need to create test posts directly on Heroku.

Once you've identified the issue, try these solutions:

• Fix missing migrations: If logs mention unapplied migrations, run heroku run python manage.py migrate to apply them. Make sure all migration files are committed to Git before pushing to Heroku—if you forgot to add them, commit and push again first.
• Fix static file serving:
  • Ensure whitenoise is installed (it's part of the Django Girls tutorial). Add 'whitenoise.middleware.WhiteNoiseMiddleware' to your MIDDLEWARE list in settings.py, right after django.middleware.security.SecurityMiddleware.
  • Set STATIC_ROOT = os.path.join(BASE_DIR, 'staticfiles') in settings.py, then re-run heroku run python manage.py collectstatic --noinput.
• Transfer or add data to Heroku's database:
  • If you want to copy your local SQLite data to Heroku, use heroku pg:push (note: SQLite and PostgreSQL have minor differences, so test this carefully).
  • Alternatively, create test posts directly on Heroku via the admin interface (if you set up the admin) or using the Django shell command mentioned earlier.
• Reset DEBUG safely: After debugging, set DEBUG back to False with heroku config:set DEBUG=False to keep your app secure in production.

内容的提问来源于stack exchange，提问作者anonymous