I am just starting with Django, and I would like to make an app that uses my existing sqlite db.
I read the docs and I found that you can create models from a db, using inspectdb; altho I can't find an example of how you use that command, on an existing db.
I copied the db file inside the directory of my project, ran the command and I see that a sqlite3 file is created in my directory project.
Altho the file has nothing to do with the database that I made. I tried to pass the db name to the inspectdb command but it says that it doesn't accept parameters.
So how can I actually tell the command to use my db to create the model for my app?
There must be some obvious step that I am missing...this is what I did:
-created the project
-created the app
-copied my db inside the project folder
-ran inspectdb
But I see the model empty, and a new db called db.sqlite3 created
Found the answer: there is a variable that has to be set, to define which one is the db that the application will use. the default is set to "db.sqlite3", which explain why I am getting this behavior.
Once you modify the name with the database that I already made, the command run without issues.
Not sure if it is just me getting stomped, but this info about the name that has to be changed was not mentioned anywhere...
Thanks
I have a model called snacks:
class Snack(models.Model):
snack = models.CharField(max_length=9)
When I do
Snack.objects.get_or_create(snack="borsh")
I get this error:
django.db.utils.IntegrityError: duplicate key value violates unique constraint "restaurants_snack_pkey"
DETAIL: Key (id)=(6) already exists.
If I do it again, it's going to tell me the same thing except the key (that already exists) will be 7 and so on.
It's true that the key already exists, I'm wondering how can I make it pick a key that's the next one available?
Thanks in advance.
Jenia
You probably did some manual data importing, even if not, it's not problem with django, but with database auto increment sequence. Django has a management command that generates sql command to reset those:
./manage.py sqlsequencereset myapp1 myapp2
If you are using PostgreSQL you can just pipe it in like that:
./manage.py sqlsequencereset myapp1 myapp2 | psql
or mysql if you are using MySQL, but I haven't ried it.
My django app works with tables that are not managed and have the following defined in my model like so:
class Meta:
managed = False
db_table = 'mytable'
When I run a simple test that imports the person, I get the following:
(person)bob#sh ~/person/dapi $ > python manage.py test
Creating test database for alias 'default'...
DatabaseError: (1060, "Duplicate column name 'db_Om_no'")
The tests.py is pretty simple like so:
import person.management.commands.dorecall
from person.models import Person
from django.test import TestCase
import pdb
class EmailSendTests(TestCase):
def test_send_email(self):
person = Person.objects.all()[0]
Command.send_email()
I did read in django docs where it says "For tests involving models with managed=False, it’s up to you to ensure the correct tables are created as part of the test setup.". So I understand that my problem is that I did not create the appropriate tables. So am I supposed to create a copy of the tables in the test_person db that the test framework created?
Everytime I run the tests, the test_person db gets destroyed (I think) and re-setup, so how am I supposed to create a copy of the tables in test_person. Am I thinking about this right?
Update:
I saw this question on SO and added the ManagedModelTestRunner() in utils.py. Though ManagedModelTestRunner() does get run (confirmed through inserting pbd.set_trace()), I still get the Duplicate column name error. I do not get errors when I do python manage.py syncdb (though this may not mean much since the tables are already created - will try removing the table and rerunning syncdb to see if I can get any clues).
I had the same issue, where I had an unmanaged legacy database that also had a custom database name set in the models meta property.
Running tests with a managed model test runner, as you linked to, solved half my problem, but I still had the problem of Django not knowing about the custom_db name:
django.db.utils.ProgrammingError: relation "custom_db" does not exist
The issue was that ./manage.py makemigrations still creates definitions of all models, managed or not, and includes your custom db names in the definition, which seems to blow up tests. By installing:
pip install django-test-without-migrations==0.2
and running tests like this:
./manage.py test --nomigrations
I was able to write tests against my unmanaged model without getting any errors.
I've started working on a Django/Postgres site. Sometimes I work in manage.py shell, and accidentally do some DB action that results in an error. Then I am unable to do any database action at all, because for any database action I try to do, I get the error:
current transaction is aborted, commands ignored until end of transaction block
My current workaround is to restart the shell, but I should find a way to fix this without abandoning my shell session.
(I've read this and this, but they don't give actionable instructions on what to do from the shell.)
You can try this:
from django.db import connection
connection._rollback()
The more detailed discussion of This issue can be found here
this happens to me sometimes, often it's the missing
manage.py migrate
or
manage.py syncdb
as mentioned also here
it also can happen the other way around, if you have a schemamigration pending from your models.py. With south you need to update the schema with.
manage.py schemamigration mymodel --auto
Check this
The quick answer is usually to turn on database level autocommit by adding:
'OPTIONS': {'autocommit': True,}
To the database settings.
I had this error after restoring a backup to a totally empty DB. It went away after running:
./manage syncdb
Maybe there were some internal models missing from the dump...
WARNING: the patch below can possibly cause transactions being left in an open state on the db (at least with postgres). Not 100% sure about that (and how to fix), but I highly suggest not doing the patch below on production databases.
As the accepted answer does not solve my problems - as soon as I get any DB error, I cannot do any new DB actions, even with a manual rollback - I came up with my own solution.
When I'm running the Django-shell, I patch Django to close the DB connection as soon as any errors occur. That way I don't ever have to think about rolling back transactions or handling the connection.
This is the code I'm loading at the beginning of my Django-shell-session:
from django import db
from django.db.backends.util import CursorDebugWrapper
old_execute = CursorDebugWrapper.execute
old_execute_many = CursorDebugWrapper.executemany
def execute_wrapper(*args, **kwargs):
try:
old_execute(*args, **kwargs)
except Exception, ex:
logger.error("Database error:\n%s" % ex)
db.close_connection()
def execute_many_wrapper(*args, **kwargs):
try:
old_execute_many(*args, **kwargs)
except Exception, ex:
logger.error("Database error:\n%s" % ex)
db.close_connection()
CursorDebugWrapper.execute = execute_wrapper
CursorDebugWrapper.executemany = execute_many_wrapper
For me it was a test database without migrations. I was using --keepdb for testing. Running it once without it fixed the error.
There are a lot of useful answers on this topic, but still it can be a challenge to figure out what is the root of the issue. Because of this, I will try to give just a little more context on how I was able to figure out the solution for my issue.
For Django specifically, you want to turn on logs for db queries and before the error is raised, you can find the query that is failing in the console. Run that query directly on db, and you will see what is wrong.
In my case, one column was missing in db, so after migration everything worked correctly.
I hope this will be helpful.
If you happen to get such an error when running migrate (South), it can be that you have lots of changes in database schema and want to handle them all at once. Postgres is a bit nasty on that. What always works, is to break one big migration into smaller steps. Most likely, you're using a version control system.
Your current version
Commit n1
Commit n2
Commit n3
Commit n4 # db changes
Commit n5
Commit n6
Commit n7 # db changse
Commit n8
Commit n9 # db changes
Commit n10
So, having the situation described above, do as follows:
Checkout repository to "n4", then syncdb and migrate.
Checkout repository to "n7", then syncdb and migrate.
Checkout repository to "n10", then syncdb and migrate.
And you're done. :)
It should run flawlessly.
If you are using a django version before 1.6 then you should use Christophe's excellent xact module.
xact is a recipe for handling transactions sensibly in Django applications on PostgreSQL.
Note: As of Django 1.6, the functionality of xact will be merged into the Django core as the atomic decorator. Code that uses xact should be able to be migrated to atomic with just a search-and-replace. atomic works on databases other than PostgreSQL, is thread-safe, and has other nice features; switch to it when you can!
I add the following to my settings file, because I like the autocommit feature when I'm "playing around" but dont want it active when my site is running otherwise.
So to get autocommit just in shell, I do this little hack:
import sys
if 'shell' in sys.argv or sys.argv[0].endswith('pydevconsole.py'):
DATABASES['default']['OPTIONS']['autocommit'] = True
NOTE: That second part is just because I work in PyCharm, which doesnt directly run manage.py
I got this error in Django 1.7. When I read in the documentation that
This problem cannot occur in Django’s default mode and atomic()
handles it automatically.
I got a bit suspicious. The errors happened, when I tried running migrations. It turned out that some of my models had my_field = MyField(default=some_function). Having this function as a default for a field worked alright with sqlite and mysql (I had some import errors, but I managed to make it work), though it seems to not work for postgresql, and it broke the migrations to the point that I didn't event get a helpful error message, but instead the one from the questions title.
I'm not 100% sure I'm doing this right, but I think I've found an issue where auth.Permission objects aren't being created soon enough for migrations to use them when you initialize a DB from scratch.
The important details:
I'm trying to initialize a Django DB from scratch using ./manage.py syncdb --migrate --noinput
I have 11 migrations in my chain
The 1st migration creates a new model called myapp.CompanyAccount
The 9th migration tries to fetch the permission myapp.change_companyaccount with:
p = orm[ "auth.Permission" ].objects.get( codename = "change_companyaccount" )
At that point, an exception is raised:
django.contrib.auth.models.DoesNotExist: Permission matching query does not exist
I had assumed that the default permissions that are defined for every object (as per http://docs.djangoproject.com/en/dev/topics/auth/#default-permissions) would have been created by the time the 1st migration finished, but it doesn't appear that they are. If I re-run the migration after the exception, it works the second time because apparently the permission now exists and the 9th migration can execute without error.
Is there anything that can be done to "flush" everything sometime before the 9th migration runs so that the whole thing can run in a single pass without bailing out?
Thanks for any help / advice.
EDIT: In response to John's comment below, I found out that the following command-line sequence will work:
./manage.py syncdb (this initializes the default Django tables)
./manage.py migrate myapp 0001 (this causes the CompanyAccount table to be created)
./manage.py migrate myapp (this migrates all the way to the end without error)
Unfortunately, skipping step #2 above means that you get the same exception in the 0009 migration, which tells me that my original suspicion was correct that default permissions on new models are not created by South immediately, and are somehow only pushed into the database when the entire migration chain finishes.
This is better than where I was (I'm at least avoiding exceptions now) but I still need to manually segment the migration around the creation of new models that latter migrations might need to touch the permissions of, so this isn't a complete solution.
As it turns out, the answer is to manually call db.send_pending_create_signals() at some point before you try to access the default permission since South only does this "flushing" step quite late in the process. Thanks to Andrew Godwin from South for replying to this on the South mailing list here:
http://groups.google.com/group/south-users/browse_thread/thread/1de2219fe4f35959
Don't you have to run the default "syncdb" on a virgin database in order to create the South migration table; before you can use south. Are you doing that? It typically creates the permissions table at that time since you have django.contrib.auth in your INSTALLED_APPS.
http://south.aeracode.org/docs/installation.html#configuring-your-django-installation