Django how make makemigrations and migrate when making changes at models - python

Whenever I make changes to the models (and subsequently to the views) when I do makemigrations or migration, I always run into problems. Sometimes running makemigrations django notices the changes, but then when I run the command migrate django writes that there are no changes to be made. Other times, dozens of exceptions are generated during makemigrations. Django writes that he does not find certain tables or certain fields but I read that the errors report the names before my changes.
The only solution to all this is to delete content of:
_pycache_
views.py
sql3.db3 database
Leave only models.py. At this point I can proceed with the makemigrations and migrate commands.
The question: is there an easier way? What am I wrong?

Related

Stop Django background-task from deleting completed_task model

On django-background-tasks==1.1.11 (Django==2.2, Python 3.6.9), I have this problem where everytime I run python manage.py migrate, the table background_task_completedtask gets deleted. This breaks my background tasks. So far I have found a way to reverse it, as it is a separate migration from the initial one, meaning I can just python manage.py migrate background_task 0001_initial to restore it, but this does mean it will still be removed next migration.
Any ideas for a more permanent solution?
Found a (somewhat hacky) permanent solution myself:
By faking migrations (python manage.py migrate --fake (or python manage.py migrate appname --fake)), you make django think the migration has been executed without actually executing it. By doing this with the migration that was bothering me, I managed to get everything working again.

Django force migrations/database syncing

I had my migrations file in version control, and it went out of sync between production and development (I know, that was the mistake, but it's happened now).
As a result, I couldn't run migrations in production. I deleted the migrations folder, and then re-ran makemigrations and migrate. makemigrations logs out creating all the fields. However, migrate simply says "no migrations to apply", and the extra fields do not appear in the database.
All I've changed is adding nullable fields to a model, so it should be a straightforward migration.
I can drop the whole db and start over, but I'd prefer not to because it takes a long time to re-populate.
Is there a way that I can force Django to find the differences between the DB and the models, and build the correct migrations to add the fields?
I attempted adding nonsense models to try and trigger a refresh. But that hasn't changed anything.

Django Custom Auth Migration

I was trying to alter something on my user model in django and in the process I used makemigration to generate the migration file for it. But then decided against the whole thing, but now I have an unmigrated migration file located somewhere and I can't find it. I don't have an auth migrations folder in my app and I looked in the django auth migrations file and it's not there either. It shows up when I run python manage.py showmigrations as unmigrated, but I don't see the file anywhere. It doesn't show up when I do git status either.
Now I'm stuck because I can't run migrate without it trying to migrate it and erroring. This is probably something silly that I'm overlooking. :-/
You can either delete the table manually or inspect all migrations with:
./manage.py showmigrations my_app

Django - Migrate command says that table exists after second makemigrations was executed

I have one model with the relevant fields setup. I ran manage.py migrate then it created the a table in my database. I then ran manage.py makemigrations so that it could create an initial migration file with prefix '0001'. I added another field to my model and then ran manage.py makemigrations again, which created another migration file with prefix '0002'. When I run manage.py migrate now it still looks at the first migration file and so throws out an error that the 'Table already exists'. How can I make it only look at the latest migration file so that it adds the new column to the table? I'm using MySQL.
This will never happen unless django detects (thinks) that the database has not been setup, and tries to initialise the tables with a schema.
Looks like your tables are already setup, but this is not known to django. That is why it tries to start applying the first migration - the table creation and schema is included in that.
You can use the --fake and --fake-initial options as per your specific problem, which tell django that the tables are already setup and ready, and to fake the migrations.
Useful links for more info:
django migrations - django documentation
django migrations, a primer - realpython
how to redo a migration after fake - stackoverflow

Django 1.7 - makemigrations not detecting changes

As the title says, I can't seem to get migrations working.
The app was originally under 1.6, so I understand that migrations won't be there initially, and indeed if I run python manage.py migrate I get:
Operations to perform:
Synchronize unmigrated apps: myapp
Apply all migrations: admin, contenttypes, auth, sessions
Synchronizing apps without migrations:
Creating tables...
Installing custom SQL...
Installing indexes...
Running migrations:
No migrations to apply.
If I make a change to any models in myapp, it still says unmigrated, as expected.
But if I run python manage.py makemigrations myapp I get:
No changes detected in app 'myapp'
Doesn't seem to matter what or how I run the command, it's never detecting the app as having changes, nor is it adding any migration files to the app.
Is there any way to force an app onto migrations and essentially say "This is my base to work with" or anything? Or am I missing something?
My database is a PostgreSQL one if that helps at all.
If you're changing over from an existing app you made in django 1.6, then you need to do one pre-step (as I found out) listed in the documentation:
python manage.py makemigrations your_app_label
The documentation does not make it obvious that you need to add the app label to the command, as the first thing it tells you to do is python manage.py makemigrations which will fail. The initial migration is done when you create your app in version 1.7, but if you came from 1.6 it wouldn't have been carried out. See the 'Adding migration to apps' in the documentation for more details.
This may happen due to the following reasons:
You did not add the app in INSTALLED_APPS list in settings.py
(You have to add either the app name or the dotted path to the subclass of AppConfig in apps.py in the app folder, depending on the version of django you are using). Refer documentation: INSTALLED_APPS
You don't have migrations folder inside those apps. (Solution: just create that folder).
You don't have __init__.py file inside migrations folder of those apps. (Solution: Just create an empty file with name __init__.py)
You don't have an __init__.py file inside the app folder. (Solution: Just create an empty file with name __init__.py)
You don't have a models.py file in the app
Your Python class (supposed to be a model) in models.py doesn't inherit django.db.models.Model
You have some semantic mistake in definition of models in models.py
Note:
A common mistake is to add migrations folder in .gitignore file. When cloned from remote repo, migrations folder and/or __init__.py files will be missing in local repo. This causes problem.
Migration files are supposed to be included in the repo. read here. If your team frequently faces migration issues you may consider ignoring migration files as follows:
I suggest to gitignore migration files by adding the following lines to .gitignore file
*/migrations/*
!*/migrations/__init__.py
Remember, it is not recommended to gitignore migration files as per django documentation
Ok, looks like I missed an obvious step, but posting this in case anyone else does the same.
When upgrading to 1.7, my models became unmanaged (managed = False) - I had them as True before but seems it got reverted.
Removing that line (To default to True) and then running makemigrations immediately made a migration module and now it's working. makemigrations will not work on unmanaged tables (Which is obvious in hindsight)
My solution was not covered here so I'm posting it. I had been using syncdb for a project–just to get it up and running. Then when I tried to start using Django migrations, it faked them at first then would say it was 'OK' but nothing was happening to the database.
My solution was to just delete all the migration files for my app, as well as the database records for the app migrations in the django_migrations table.
Then I just did an initial migration with:
./manage.py makemigrations my_app
followed by:
./manage.py migrate my_app
Now I can make migrations without a problem.
Agree with #furins. If everything seems to be in order and yet this problem arises, checkout if there is any property method with same title as the attribute which you are trying to add in the Model class.
Remove method with similar name as attribute you are adding.
manage.py makemigrations my_app
manage.py migrate my_app
Add the methods back.
This is kind of a stupid mistake to make, but having an extra comma at the end of the field declaration line in the model class, makes the line have no effect.
It happens when you copy paste the def. from the migration, which itself is defined as an array.
Though maybe this would help someone :-)
Maybe I am too late but did you try to have a migrations folder in your app with a __init__.py file in it?
Maybe this will help someone. I was using a nested app. project.appname and I actually had project and project.appname in INSTALLED_APPS. Removing project from INSTALLED_APPS allowed the changes to be detected.
The answer is on this stackoverflow post, by cdvv7788 Migrations in Django 1.7
If it is the first time you are migrating that app you have to use:
manage.py makemigrations myappname Once you do that you can do:
manage.py migrate If you had your app in database, modified its model
and its not updating the changes on makemigrations you probably havent
migrated it yet. Change your model back to its original form, run the
first command (with the app name) and migrate...it will fake it. Once
you do that put back the changes on your model, run makemigrations and
migrate again and it should work.
I was having the exact same trouble and doing the above worked perfectly.
I had moved my django app to cloud9 and for some reason I never caught the initial migration.
Following worked for me:
Add the app name to settings.py
use 'python manage.py makemigrations'
use 'python manage.py migrate'
Worked for me: Python 3.4, Django 1.10
People like me who don't like migrations can use steps below.
Remove changes what you want to sync.
Run python manage.py makemigrations app_label for the initial migration.
Run python manage.py migrate for creating tables before you make changes.
Paste changes which you remove at first step.
Run 2. and 3. steps.
If you confused any of these steps, read the migration files. Change them to correct your schema or remove unwanted files but don't forget to change next migration file's dependencies part ;)
I hope this will help someone in future.
You want to check the settings.py in the INSTALLED_APPS list and make sure all the apps with models are listed in there.
Running makemigrations in the project folder means it will look to update all the tables related to all the apps included in settings.py for the project. Once you include it, makemigrations will automatically include the app (this saves a lot of work so you don't have to run makemigrations app_name for every app in your project/site).
Just in case you have a specific field that does not get identified by makemigrations: check twice if you have a property with the same name.
example:
field = django.db.models.CharField(max_length=10, default = '', blank=True, null=True)
# ... later
#property
def field(self):
pass
the property will "overwrite" the field definition so changes will not get identified by makemigrations
Adding this answer because only this method helped me.
I deleted the migrations folder run makemigrations and migrate.
It still said: No migrations to apply.
I went to migrate folder and opened the last created file,
comment the migration I wanted(It was detected and entered there)
and run migrate again.
This basically editing the migrations file manually.
Do this only if you understand the file content.
Make sure your model is not abstract. I actually made that mistake and it took a while, so I thought I'd post it.
Did u use schemamigration my_app --initial after renaming old migration folder? Try it. Might work. If not - try to recreate the database and make syncdb+migrate. It worked for me...
In my case I needed to add my model to the _init_.py file of the models folder where my model was defined:
from myapp.models.mymodel import MyModel
I had mistakely deleted folder of migrations from my project directory.
Solution is to create __init__.py file in the migrations folder, and then,
python manage.py makemigrations
python manage.py migrate
Had the same problem
Make sure whatever classes you have defined in models.py, you must have to inherit models.Model class.
class Product(models.Model):
title = models.TextField()
description = models.TextField()
price = models.TextField()
I had the same problem with having to run makemigrations twice and all sorts of strange behaviour. It turned out the root of the problem was that I was using a function to set default dates in my models so migrations was detecting a change every time I ran makemigrations. The answer to this question put me on the right track: Avoid makemigrations to re-create date field
I recently upgraded Django from 1.6 to 1.8 and had few apps and migrations for them. I used south and schemamigrations for creating migrations in Django 1.6, which is dropped in Django 1.8.
When I added new models after upgrade, the makemigrations command wasn't detecting any changes. And then I tried the solution suggested by #drojf (1st answer), it worked fine, but failed to apply fake initial migration (python manage.py --fake-initial). I was doing this as my tables (old tables) were already created.
Finally this worked for me, removed new models (or model changes) from models.py and then had to delete (or rename for safety backup) migrations folder of all apps and run python manage.py makemigrations for all apps, then did python manage.py migrate --fake-initial. This worked like a charm. Once initial migration is created for all apps and fake initial migrated, then added new models and followed regular process of makemigrations and migrate on that app. The changes were detected now and everything went fine.
I just thought of sharing it here, if someone faces same problem (having schemamigrations of south for their apps), it might help them :)
Maybe that can help someone, I had the same problem.
I've already created two tables with the serializer class and the views.
So when I wanted to updated, I had this error.
I followed this steps:
I made .\manage.py makemigrations app
I executed .\manage.py migrate
I erased both tables of my models.py
I erased all reference to my tables from serializer and view class.
I executed step 1 and 2.
I retrieved my changes just in the models.py
I executed again step 5.
I restored all my changes.
If you're working with Pycharm, local history is very helpfull.
Maybe this will help someone.
I've deleted my models.py and expected makemigrations to create DeleteModel statements.
Remember to delete *.pyc files!
./manage makemigrations
./manage migrate
Migrations track changes to DB so if youre changing from unmanaged to managed, you'll need to make sure that youre database table is up to date relating to the Model you're dealing with.
If you are still in dev mode, I personally decided to delete the migration files in my IDE as well as in the django_migrations table relating to my Model and rerun the above command.
REMEMBER: if you have a migration that ends with _001 in your IDE & _003 in your database. Django will only see if you have a migration ending with _004 for anything to update.
The 2 (code & db migrations) are linked and work in tandem.
Happy coding.
You may need to fake the initial migrations using the command below
python manage.py migrate --fake-initial
Remove changes what you want to sync.
Run python manage.py makemigrations app_label for the initial migration.
Run python manage.py migrate for creating tables before you make changes.
Paste changes which you remove at first step.
Run 2. and 3. steps
Added this answer because none of other available above worked for me.
In my case something even more weird was happening (Django 1.7 Version), In my models.py I had an "extra" line at the end of my file (it was a blank line) and when I executed the python manage.py makemigrations command the result was: "no changes detected".
To fix this I deleted this "blank line" that was at the end of my models.py file and I did run the command again, everything was fixed and all the changes made to models.py were detected!
First this solution is applicable to those who are facing the same issue during deployment on heroku server, I was facing same issue.
To deploy, there is a mandatory step which is to add django_heroku.settings(locals()) in settings.py file.
Changes:
When I changed the above line to django_heroku.settings(locals(), databases=False), it worked flawlessly.
I have encountered this issue, the command
python manage.py makemigrations
worked with me once I saved the changes that I made on the files.
One of the cause may be You didn't register your models in admin.py file .
First register your models in admin.py file then do the migrations.

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