Python Django - 内部错误 ProgrammingError 关系不存在

Question

This might probably be a duplicated question, but I can't find a post to answer my questions yet. Any post that is similar to this may help is appreciated.

I tried to host my Django app using heroku.com

git add .
git commit -m "(commit_name)"
git push heroku master

When I tried to test the website ( /questions/1 ), the website shows an Error 500 (Internal Error). First it shows a ProgrammingError: relation does not exist. After that I did $ heroku run python manage.py migrate try to solve the problem. The original error disappeared, but instead this happened:

2020-08-29T11:05:42.668070+00:00 app[web.1]: Internal Server Error: /questions/1
2020-08-29T11:05:42.668070+00:00 app[web.1]:
2020-08-29T11:05:42.668070+00:00 app[web.1]: DoesNotExist at /questions/1
2020-08-29T11:05:42.668071+00:00 app[web.1]: Question matching query does not exist.

Settings.py :

import django_heroku

from pathlib import Path

import os

#--------------------(ommited)--------------------#

# SECURITY WARNING: don't run with debug turned on in production!
DEBUG = False

ALLOWED_HOSTS = ['*']


# Application definition

INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'myapp',
]

MIDDLEWARE = [
    'django.middleware.security.SecurityMiddleware',
    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.middleware.common.CommonMiddleware',
    'django.middleware.csrf.CsrfViewMiddleware',
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.contrib.messages.middleware.MessageMiddleware',
    'django.middleware.clickjacking.XFrameOptionsMiddleware',
]

ROOT_URLCONF = 'myweb.urls'

TEMPLATES = [
    {
        'BACKEND': 'django.template.backends.django.DjangoTemplates',
        'DIRS': [os.path.join(BASE_DIR, 'templates'),],
        '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',
            ],
        },
    },
]

WSGI_APPLICATION = 'myweb.wsgi.application'


# Database
# https://docs.djangoproject.com/en/3.1/ref/settings/#databases

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': BASE_DIR / 'db.sqlite3',
    }
}


# Password validation
# https://docs.djangoproject.com/en/3.1/ref/settings/#auth-password-validators

AUTH_PASSWORD_VALIDATORS = [
    {
        'NAME': 'django.contrib.auth.password_validation.UserAttributeSimilarityValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.MinimumLengthValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.CommonPasswordValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.NumericPasswordValidator',
    },
]


# Internationalization
# https://docs.djangoproject.com/en/3.1/topics/i18n/

LANGUAGE_CODE = 'zh-Hant'

TIME_ZONE = 'Asia/Taipei'

USE_I18N = True

USE_L10N = True

USE_TZ = True


# Static files (CSS, JavaScript, Images)
# https://docs.djangoproject.com/en/3.1/howto/static-files/

STATIC_URL = '/static/'
STATICFILES_DIRS = [
    os.path.join(BASE_DIR, 'static'),
]

STATICFILES_STORAGE = 'whitenoise.storage.CompressedManifestStaticFilesStorage'

STATIC_ROOT = os.path.join(BASE_DIR, 'static')

# Activate Django-Heroku.
django_heroku.settings(locals())

Models.py :

from django.db import models
from django.utils import timezone
import json

# Create your models here.

class Code(models.Model):
    code = models.TextField()
    number = models.IntegerField()

class Question(models.Model):
    title = models.TextField()
    text = models.TextField()
    judges = models.TextField()
    number = models.IntegerField()

    class Meta:
        ordering = ['number']

    def set_judges(self, x):
        self.judges = json.dumps(x)

    def get_judges(self):
        return json.loads(self.judges)

wsgi.py :

import os

from dj_static import Cling
from django.core.wsgi import get_wsgi_application

os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'myweb.settings')

application = Cling(get_wsgi_application())

Any suggestions or things I should try? Thank you.

[EDIT]: It seems that the database is empty now so it cause the error. But when I run the same file in my computer as I git push to heroku, the database isn't empty and it works fine.

Answer 1

According to your settings file, you are using sqlite as the database, and you can't use it in Heroku.

Heroku uses an an ephemeral filesystem .

You can write to it, and you can read from it, but the contents will be cleared periodically. If you were to use SQLite on Heroku, you would lose your entire database at least once every 24 hours.

That's why it works locally but not on Heroku, you need to use another database engine like postgresql for example.

Learn more about it at: https://help.heroku.com/K1PPS2WM/why-are-my-file-uploads-missing-deleted