This problem is basically the same as the previous question
here.
However, the answer there does not work for me. I've installed the trunk version of south, manually entered the import line in the migration file in question, and done a full 'startmigration' in a separate directory and examined the 0001_initial.py file.
I have a Django project with several applications in it, one of them (named 'core') being referred to by the others. The south migration is trying to create a new table, with a column that has a foreign key to a model in core.
I'm currently importing core in the migration in question (0006), and I even added it to migration 0001, although it doesn't seem like that should matter.
Before I do something drastic, like removing that field, running the migration, and adding the field manually, is there a known manual workaround for fixing this south issue?
You probably did not use the --freeze option like this:
python manage.py startmigration <appname> migrate_core --freeze core
Having created a migration like so:
./manage.py startmygration appname --model NewModel
This error occurs:
"The model 'program' from the app 'core' is not available in this migration."
Recreating the migration like this fixes it:
./managepy startmigration appname --model NewModel --freeze core.Program
Just doing "--freeze core" did not do the trick for me.
You can receive this error by trying to access a class that resides in another django app. Check to make sure the class you are trying to access is in the models dictionary.
Related
I have trouble with django model migrations.
I have some models in my app, and I already have some data inside.
When I added some models in my application, and I run makemigrations, the app report that there is no change.
I know that sometimes some errors came when migrate, so I delete django_migrations table in my database and run makemigrations again, and now program found my new fields.
The problem now is that if I run migrate system tell me that some tables already exist. (Which is ok and correct, because they do). I don't want to delete those tables, because I have data already inside.
I can't run migrate --fake, because program will think that I already have all the tables, which is not true.
So, I am looking for a way to tell the program : run migration, if table exist skip it. (--fake it)
Another question is why is this happening to me, that makemigrations don't recognise my changes (some cache problems,...)?
How about doing this way ?
python manage.py makemigrations
(Skip this step if you have already have migration file ready)
It will create migrations for that package lets say with a name like 0001_initial.py
Edit the file manually so that you delete all models there except that was already created in database.
Now you do a fake migration. This will sync your database with models.
python manage.py migrate --fake
Then run makemigrations again to have rest of the tables created along with a new migration file.
python manage.py makemigrations
Regarding your other question, Why makemigrations didn't recogonize your models can be because of reasons like:
Migrations for those changes are already there in some migration file.
You missed it to mention package_name in INSTALLED_APPS but i believe you did it here.
every time you make changes to your models, try these steps :
python manage.py makemigrations [your app name]
then:
python manage.py migrate
it should work fine. but remember if you have already data(rows) in your tables you should specify the default value for each one the queries.
if not, Django prompt you to specify the default value for them
or you can just try to use blank=True or null=True in your fields like below :
website = models.URLField(blank=True)
the possible cause or this is that you have another migration in the same folder starts with the same prefix... maybe you make another migration on the same table on another branch or commit so it's saved to the db with the same prefix ie: 00010_migration_from_commit_#10, 00010_migration_from_commit_#11
the solution for this is to rename the migration file like this 00011_migration_from_commit_#11
I tried to edit the related migration file and commented the part where it creates that specific column, then ran python manage.py migrate
The main problem is the existing tables that are disabling the migration of the new tables, so the solution is straight-forward:
** Try to add managed = False to the existing dB so it won't be detected by migrate
** Redo it for all existing old tables :
class Meta:
managed=False
It sometimes gets boring when we have a lot of tables in the same application but it works perfectly!
I just followed this procedure:
makemigrations (success)
migrate (success)
Copy the app on another server (with the migration files)
Create a new empty database on that server
migrate (success, it creates the correct schema)
Fill the new database with data
Just to test: migrate ....
At this point Django says I have "changes that are not yet reflected in a migration, and so won't be applied. Run 'manage.py makemigrations' to make new migrations, and then re-run 'manage.py migrate' to apply them"
But when I run makemigrations, it creates a new one that wants to "Remove field" every foreign key and "Delete model" all of my models. If I run it it empties my database. My models.py are intact.
What is happening ??
I had the same problem in my project. Running forward I can say that django removes models that has no import (making the Delete model migration). The documentation says that you should import your model in the myApp/models/__init__.py file (see https://docs.djangoproject.com/en/1.11/topics/db/models/#organizing-models-in-a-package).
In my case I imported the model somewhere to make manipulations but model had been removing elsewhere.
I had made a useless import in an admin.py file that has solved my situation (I didn't try to follow the documentation and import it in the __init__.py but sure it should help).
I had not realized yet why does it work that way (hope that someone could note this moment) and also hope this solution will help you.
I've just had the same errors, but I hit the makemigrations building a migration full of Remove Field and Delete Model commands before I tried the migrate command.
In my case, the solution was related this being an old project I was resurrecting, and it had a number of Model.Meta.app_name values set, as well as entries in apps.py for each project. These were now in conflict with the way settings was interpreting the project, and even though my models were imported into views and admin, they weren't being seen by the migration code. Deleting these app_name tags on the models, and modifying the AppConfig name in apps.py solved this, so that the running makemigrations again caused the expected changes (alter field, etc), and all was fine.
I didn't find any other questions or answers that quite matched this one and my experience, so I hope if anyone else looks for this, they'll find it here like I did ;-)
I have a django 1.8 app working with a db.
I'm trying to change the schema of a table using the built-in migration.
Here are the steps I did:
In my dev invironment, I grabbed the app source and ran
python manage.py sycdb
then I ran
python manage.py loaddata ~/my_data.json
then I modified modes.py. Added a field and renamed a field...all from the same table 'TABLE1' which had no data.
then
python manage.py makemigrations myapp
python manage.py migrate
Error: django.db.utils.OperationalError: table "myapp_someother_table" already exists
then ran
python manage.py migrate --fake-initial
worked!
but when I browsed to the admin page for TABLE1, I get this error:
OperationalError: no such column: myapp_table1.my_new_field_id
I checked the db and yes, there is no such column.
How can I procceed from here? I prefer to fix this via django.
If I fix it straight in the db, then the migration goes out of sync.
Migrations do not automagically see that you have made changes. Migrations detect changes by comparing the current model with the historical model saved in the migration files.
In this case, you didn't have any historical models, since you didn't have any migrations. Django was not able to detect any changes in your models, even though they were different from your database.
The correct way to make changes to your model is to first run manage.py makemigration <my_app>, and then make the changes to your model, followed by another manage.py makemigrations.
You might not be able to do it via pure django and keep your data. I don't have personal experience with south but there are a lot of mentions if this tool. Just in case if nothing else works for you...
Here is what I did to make things work, but there must be a better way so please add more answers/comments...
I deleted the sqlite db and the migration folder
I made the desired changes to model.py
ran syncdb
ran loaddata to load the json data dump that I had saved previously.
just started the dev server
I have an app which is managed with South for quite a while. At one point of the development, I added a custom field to a model that had a pip requirement (sorl-thumbnail), but I removed this requirement later. My problem is that when I try to migrate this app in a fresh new database, South shouts:
./manage.py migrate my_app
...
ValueError: Cannot import the required field 'sorl.thumbnail.fields.ImageField'
How am I suppose to deal with this old requirement?
Maybe a dirty solution but if you really want to get rid of your sorl-thumbnail dependency you don't have much choice :
Locate the migration file in which the field was added and replace sorl.thumbnail.fields.ImageField by something like django.db.models.fields.files.ImageField
It should work unless you have DataMigrations depending on special features of sorl-thumbnail.
I'm using sqlite3 and pycharm to learn more about django, and googled to find that south is recommended to make it easier to modify models after they have been created.
I'm trying to follow the advice on http://south.aeracode.org/docs/tutorial/part1.html#starting-off.
The most success I've had so far is to create a simple model and run syncdb before adding south to installed_apps. That way the intial tables are created and I get a chance to create a super user. (Django admin seems to fret if there are no users).
Then I add south to installed_apps, and run django_manage.py schemamigration bookmarks --initial
It seems to work fine. A new directory is created called migrations with a couple of files in it in my app folder and an encouraging message.
"Created 0001_initial.py. You can now apply this migration with: ./manage.py migrate bookmarks"
The next step - django_manage.py" migrate bookmarks generates the following error message
django.db.utils.DatabaseError: no such table: south_migrationhistory.
I thought that table would be created in the first schememigration step. What am I missing? Can anyone help?
Marg
South uses a table if its own to keep track of which migrations have been applied. Before you can apply any migrations, this must have been created, using python ./manage.py syncdb.
As well as for setting up south, you will find syncdb sometimes necessary for non-south apps in your project, such as the very common django.contrib.auth.
Note that as a convenience, you can run both in one go like this
python ./manage.py syncdb --migrate
My latest (unsuccessful) effort was the following
Create application – synch db – superuser created
Test run –admin screen shows basic tables
Add south, and syncdb from command line with manage.py syncdb – south_migrationhistory table created. Add basic vanilla model
Tried various combinations of manage.py syncdb –manage, and
schemamigration from Pycharm (if run from within pycharm a
migrations directory is created within the app
– if run from the command line the directory does not seem to be
created.)
Django admin screen shows table – but if I try to edit
the table it says that it doesn’t exist
Check database structure
using SQLite browser - table for newly created model doesn’t exist
I’m starting to think that the whole thing is not worth the time wasting hassle – maybe I’m better off just modifying the tables in SQLite browser
Answer in the similar question:
Run syncdb to add the Django and South tables to the database.