Django - DatabaseError: No such table

Question

I defined two models:

class Server(models.Model):
    owners = models.ManyToManyField('Person')

class Person(models.Model):
    name = models.CharField(max_length=50)

admin.site.register(Server)
admin.site.register(Person)

After that I even checked the sql, just for fun:

BEGIN;
CREATE TABLE "servers_server_owners" (
    "id" integer NOT NULL PRIMARY KEY,
    "server_id" integer NOT NULL,
    "person_id" integer NOT NULL,
    UNIQUE ("server_id", "person_id")
)
;
CREATE TABLE "servers_server" (
    "id" integer NOT NULL PRIMARY KEY,
    "name" varchar(50) NOT NULL,
    "port" integer unsigned NOT NULL,
    "state" integer NOT NULL
)
;
CREATE TABLE "servers_person" (
    "id" integer NOT NULL PRIMARY KEY,
    "name" varchar(50) NOT NULL
)
;
COMMIT;

There it even says CREATE TABLE "servers_server_owners"

I ran syncdb to install the new models to the database. I went to the admin-interface to define some objects to play with, but I got the following error:

DatabaseError at /admin/servers/server/1/  
no such table: servers_server_owners

I shutdown the dev-server, ran syncdb again, started the server: Still same problem. Why can't it find, the table, even though it just told me it created id?

Solution 1

Actually the problem was that the table never got created. Since I am fairly new with django, I did not know that ./manage.py syncdb does not update existing models, but only creates the ones that do not exist.

Because the model 'Server' existed before I added the other model, and it was already in the db, 'syncdb' did not actually create the new tables.

Solution 2

As a tip for the future, look into South, a very useful utility for applying your model changes to the database without having to create a new database each time you've changed the model(s).

With it you can easily: python manage.py migrate app_name and South will write your model changes. The documentation is pretty straightforward.

Solution 3

I meet the same problem today and fix it. I think you miss some command in tutorial 1. just do follow:

./python manage.py makemigrations polls
python manage.py sql polls
./python manage.py syncdb

then fix it and gain the table polls and you can see the table created. you should read the manage.py makemigrations command.

Solution 4

for django 1.9, this is what i did and it solved the issue.

python manage.py makemigrations app_name

python manage.py migrate

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