django.db.utils.ProgrammingError: Table doesn't exist

Question

I used two databases, one is default sqlite3 and another mysql. I just created a model Post under app named theapp. I have also created routers.py.

This is settings.py

DATABASES = {
    'default': {
       'ENGINE': 'django.db.backends.sqlite3',
       'NAME': os.path.join(BASE_DIR, 'db.sqlite3'),
    },

    'customer': {
       'NAME': 'customer',
       'ENGINE': 'django.db.backends.mysql',
       'USER': 'root',
       'PASSWORD': 'haha',
    }
 }

This is routers.py

class CustomerRouter:
"""
A router to control all database operations on models in the
auth application.
"""
def db_for_read(self, model, **hints):
    """
    Attempts to read auth models go to auth_db.
    """
    if model._meta.app_label == 'theapp':
        return 'customer'
    return None

def db_for_write(self, model, **hints):
    """
    Attempts to write auth models go to auth_db.
    """
    if model._meta.app_label == 'theapp':
        return 'customer'
    return None

def allow_relation(self, obj1, obj2, **hints):
    """
    Allow relations if a model in the auth app is involved.
    """        
    if obj1._meta.app_label == 'theapp' or \
       obj2._meta.app_label == 'theapp':
       return True
    return None

def allow_migrate(self, db, app_label, model_name=None, **hints):
    """
    Make sure the auth app only appears in the 'auth_db'
    database.
    """
    if app_label == 'theapp':
        return db == 'customer'
    return None

This is my models.py

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


class Post(models.Model):
    author = models.ForeignKey('auth.User', on_delete=models.CASCADE)
    title = models.CharField(max_length=200)
    text = models.TextField()
    created_date = models.DateTimeField(
        default=timezone.now)
    published_date = models.DateTimeField(
        blank=True, null=True)

    def publish(self):
        self.published_date = timezone.now()
        self.save()

    def __str__(self):
        return self.title

This is what happening when I am trying to open posts table in admin panel

any ideas?

what software are you using on the lefthand side of the screen that lists 'versions', 'time', 'settings', etc? — GeorgeCostanza, Aug 22 '18 at 17:13

score 3 · Accepted Answer · answered Feb 26 '18 at 15:14

3

I think you have not run migrations on your MySQL database,

Try

python manage.py migrate --database=customer

Read https://docs.djangoproject.com/en/1.11/ref/django-admin/#migrate

answered Feb 26 '18 at 15:14

Nagesh Dhope

797
5
13

1

database router will work, during your read and write operations but it will not work during migrate. So you need to run migrate on all your databases this is where --database option helps – Nagesh Dhope Feb 26 '18 at 16:40
I got this error `django.utils.connection.ConnectionDoesNotExist: The connection 'db_name' doesn't exist.` – Fathy Oct 17 '22 at 10:20

score 2 · Answer 2 · answered Feb 26 '18 at 13:24

In my case, I have two databases hosted on two different servers. Both databases worked with MySQL but it's the same thing than you with SQLLite-MySQL.

Maybe this example could solve your issue, so I display what I have into my Django Web Application.

Into my settings.py file something like that :

DATABASES = {

    'default': {
        'ENGINE': 'django.db.backends.mysql',
        'NAME': 'default',
        'USER': 'osx',
        'PASSWORD': '******',
        'HOST': '172.30.10.12',
        'PORT': '3306',
        'OPTIONS': {
            'init_command': 'SET innodb_strict_mode=1',
            'sql_mode': 'traditional',
        }
    },


    'DS2': {
        'ENGINE': 'django.db.backends.mysql',
        'NAME': 'DS2',
        'USER': 'osx',
        'PASSWORD': '******',
        'HOST': '172.30.10.13',
        'PORT': '3306',
        'OPTIONS': {
            'init_command': 'SET innodb_strict_mode=1',
            'sql_mode': 'traditional',
        }
    }
}


BDD = ('default', 'DS2')
DATABASE_ROUTERS = ['MyApp.routersLocal.LocalRouter', 'MyApp.routersGlobal.GlobalRouter']

Then I have both files : routersGlobal.py and routersLocal.py :

#routersGlobal.py

from django.conf import settings

class GlobalRouter(object):
    """
A router to control all database operations on models in the
auth application.
"""

    def db_for_read(self, model, **hints):
        """
        Attempts to read auth models go to auth.
        """
        app_list = ('Identity',)

        if model._meta.app_label in app_list:
            return 'DS2'
        return None

    def db_for_write(self, model, **hints):
        """
        Attempts to write auth models go to auth.
        """
        app_list = ('Identity',)
        if model._meta.app_label in app_list:
            return 'DS2'
        return None

    def allow_relation(self, obj1, obj2, **hints):
        """
        Allow relations if a model in the auth app is involved.
        """
        app_list = ('Identity',)
        if obj1._meta.app_label in app_list and obj2._meta.app_label in app_list:
            return 'DS2'
        return None

    def allow_migrate(self, db, app_label, model=None, **hints):
        """
        Make sure the auth app only appears in the 'auth'
        database.
        """
        app_list = ('Identity',)

        if app_label in app_list:
            return db == 'DS2'
        return None

and

#routersLocal.py
from django.conf import settings

class LocalRouter(object):
    """
A router to control all database operations on models in the
auth application.
"""

    def db_for_read(self, model, **hints):
        """
        Attempts to read auth models go to auth.
        """
        app_list = ('auth', 'admin', 'contenttypes', 'sessions', 'Configurations', 'log', 'Home', 'DSCORE', 'Informations')

        if model._meta.app_label in app_list:
            return 'default'
        return None

    def db_for_write(self, model, **hints):
        """
        Attempts to write auth models go to auth.
        """
        app_list = ('auth', 'admin', 'contenttypes', 'sessions', 'Configurations', 'log', 'Home', 'DSCORE', 'Informations')
        if model._meta.app_label in app_list:
            return 'default'
        return None

    def allow_relation(self, obj1, obj2, **hints):
        """
        Allow relations if a model in the auth app is involved.
        """
        app_list = ('auth', 'admin', 'contenttypes', 'sessions', 'Configurations', 'log', 'Home', 'DSCORE', 'Informations')
        if obj1._meta.app_label in app_list and obj2._meta.app_label in app_list:
            return True
        return None

    def allow_migrate(self, db, app_label, model=None, **hints):
        """
        Make sure the auth app only appears in the 'auth'
        database.
        """
        app_list = ('auth', 'admin', 'contenttypes', 'sessions', 'Configurations', 'log', 'Home', 'DSCORE', 'Informations')

        if app_label in app_list:
            return db == 'default'
        return None

EDIT :

Did you make makemigrations and migrate ?

Yes , I did migrate thing. Is 'Identity' the app that you choose to deal with DS2? And thanks , it is so good to study your code. — Khant Htet Naing, Feb 26 '18 at 13:42
`Identity` is one of my Django application. Identity's data are stored in `DS2`. Other data coming from `sessions`, `admin`, `auth` .. are stored in my default database. That's why my default database corresponding to `Local` data and my `DS2` database corresponding to `Global`. Some instance could be connected to `DS2` in order to add data, get data ... but each instance has a local database (default in my case). — Essex, Feb 26 '18 at 13:46
So you have to write routersLocal.py under project directory(outside of apps directory)? — Khant Htet Naing, Feb 26 '18 at 14:03
I wrote both files in main directory (where settings.py are) and not module directory. — Essex, Feb 26 '18 at 14:21
I did not know migrate for the db 'customer' . thank u . It is so good to study your code. Do you have anything like a blog or github ? — Khant Htet Naing, Feb 26 '18 at 15:44
Oh I don't enter my edit with `--database=yourbase` .. :/ No I don't have a blog or a github. I'm just developping my Django Web App since 2 years now. — Essex, Feb 26 '18 at 15:51

score 0 · Answer 3 · answered Oct 22 '20 at 08:58

0

For some reason Django sometimes requires you to do

python manage.py makemigrations <application>

before

python manage.py migrate <application>

Make sure you delete the migrations and __pychache__ folders before you run the commands.

answered Oct 22 '20 at 08:58

VoidMain

957
1
8
12

django.db.utils.ProgrammingError: Table doesn't exist

3 Answers3