My team has had the Django migration files in .gitignore , and so hasn't been committing these files. Instead we've been making migrations on our production server. We discovered that this is not the recommended practice (upon encountering Should I be adding the Django migration files in the .gitignore file? ). Would it cause problems to - at this point in time - remove migrations from .gitignore, makemigrations on the development machine, commit, push, and apply the migrations on the production server? If so, how can we get around these problems?
This question is motivated largely because we need to apply a custom migration that we partially wrote ourselves. (As such there's actually an additional step between making migrations on the development machine and committing them, namely adding in our custom code to the migration file).
I think the only way is to copy over all the migrations from production server to your repo then commit them. This is most likely a manual process because your production server is the only place that tracks all migrations. You don't need to worry about how to migrate your production server because it keeps the original copy. However, all these should be done before any new migrations are added and applied.
After all is fixed, you should create new migrations in your local dev environment, add to git and push your migration to production then apply the migration. Remember to have your CI or something else check for duplicate migration files.
Related
I have a django REST project and a PostgreSQL database deployed to DigitalOcean. When I develop locally, I have a separate dockerized REST server and a separate PostgreSQL database to test backend features without touching production data.
My question arises when I'm adding/modifying model fields that require me to make migrations using python [manage.py](https://manage.py) makemigrations and python [manage.py](https://manage.py) migrate command. Here is my current situation so far:
What I was supposed to do
IN LOCAL ENV, to create the migration files,
python manage.py makemigrations
python manage.py migrate
Now commit these newly created files, something like below.
git add app/migrations/...
git commit -m 'add migration files' app/migrations/...
IN PRODUCTION ENV, run only the below command.
python manage.py migrate
What I did so far
IN LOCAL ENV, created the migration files,
python manage.py makemigrations
python manage.py migrate
I committed & pushed the changes to production WITHOUT the created migration file
IN PRODUCTION ENV, ran BOTH commands.
python manage.py makemigrations
python manage.py migrate
The production server successfully added the isActive field to the database and is working fine, but I still have a 0011_user_isActive.py migration file in my local changes that hasn't been staged/committed/pushed to github repo.
And because I ran makemigrations command in production env, it probably created the same migration file that I haven't pushed from local env.
My questions are:
What happens if I push the local migration file to production? Wouldn't it create a conflict when I run migration command on digitalocean console in the future?
How should I fix this situation?
I am just scared I'm going to corrupt/conflict my production database as I'm very inexperienced in databases and have too much to risk at the moment. Would appreciate any tips on best practices when dealing with such situations!
As docs says:
The migration files for each app live in a “migrations” directory inside of that app, and are designed to be committed to, and distributed as part of, its codebase. You should be making them once on your development machine and then running the same migrations on your colleagues’ machines, your staging machines, and eventually your production machines.
So it's best practice is to push your migration files and make your local and production migration files sync.
And if you got conflict when pushing migraions files and pulling them, the makemigrations --merge command is for solving that.
Also docs says:
Because migrations are stored in version control, you’ll occasionally come across situations where you and another developer have both committed a migration to the same app at the same time, resulting in two migrations with the same number.
Don’t worry - the numbers are just there for developers’ reference, Django just cares that each migration has a different name. Migrations specify which other migrations they depend on - including earlier migrations in the same app - in the file, so it’s possible to detect when there’s two new migrations for the same app that aren’t ordered.
When this happens, Django will prompt you and give you some options. If it thinks it’s safe enough, it will offer to automatically linearize the two migrations for you. If not, you’ll have to go in and modify the migrations yourself - don’t worry, this isn’t difficult, and is explained more in Migration files below.
Also be aware that in case of updating existed data in production, you can use RunPython in migration file. Read about it here.
I took over a Django project and discovered that migrations for various apps were not being tracked by Git. That seemed a bit problematic since my understanding was that one should always track the migrations. Is that pretty much the consensus or are there reasons not to do it?
The second part of the question has to do with the fact that I have done some work involving tweaking some migrations locally. I would now like to push the changes to production. However, I am unsure as to what the best way to combine the possible conflicts would be.
For instance, in production, I have the following:
Untracked files:
(use "git add <file>..." to include in what will be committed)
mysite/aldryn_forms/migrations/0019_auto_20200730_1455.py
mysite/apps/common/migrations/0016_auto_20200624_2028.py
mysite/apps/common/migrations/0016_auto_20200625_1125.py
mysite/apps/common/migrations/0017_merge_20200625_1129.py
mysite/apps/common/migrations/0018_auto_20200720_1743.py
mysite/apps/payment/migrations/0005_auto_20200624_2028.py
mysite/apps/payment/migrations/0005_auto_20200625_1125.py
mysite/apps/payment/migrations/0006_merge_20200625_1129.py
mysite/apps/payment/migrations/0007_auto_20200720_1743.py
mysite/apps/payment/migrations/0008_paymentmodel_course.py
mysite/apps/payment/migrations/0009_paymentmodel_user.py
mysite/apps/plugins/migrations/0016_auto_20200624_2028.py
mysite/apps/plugins/migrations/0016_auto_20200625_1125.py
mysite/apps/plugins/migrations/0017_merge_20200625_1129.py
mysite/apps/xyz/migrations/0005_auto_20200730_1455.py
Locally, I have the following:
Untracked files:
(use "git add <file>..." to include in what will be committed)
mysite/aldryn_forms/migrations/0019_auto_20201108_1623.py
mysite/apps/common/migrations/0016_auto_20201108_1623.py
mysite/apps/common/migrations/0017_auto_20201108_1806.py
mysite/apps/payment/migrations/0005_auto_20201108_1623.py
mysite/apps/plugins/migrations/0016_auto_20201108_1623.py
mysite/apps/xyz/migrations/0005_auto_20201108_1623.py
These are the files with custom work:
mysite/apps/common/migrations/0016_auto_20201108_1623.py
mysite/apps/common/migrations/0017_auto_20201108_1806.py
It appears that all the migrations existing on the production server have been applied to the production database. Hence, I have concluded that they correctly describe the state of the production DB.
What should I do to sync my local work with that currently in-production?
First I would review code for conflicts in your new migrations and migrations aplied in production.
Then backup evrything (your site and production).
if you don't finde logic errors, try copy migrations files from production to yours site and go with :
python manage.py makemigrations –merge
python manage.py migrate
if it works then it will propably work in production.
There is article about it :
https://www.algotech.solutions/blog/python/django-migrations-and-how-to-manage-conflicts/#:~:text=So%2C%20in%20order%20to%20allow,manage.py%20makemigrations%20%E2%80%93merge)
once i had it too.. annoing is that you will have to do this -merge evry new migration.
At some point I reset migrations.
When you will have database in order. You can do:
backup db and remove insert from db table : migrations
delete all migration files from porject dir
qoute all paterns in urls.py
go with makemigrations and migrate
populete new db with old data (exept migration table)
oh there is even simpler method with --fake:
https://simpleisbetterthancomplex.com/tutorial/2016/07/26/how-to-reset-migrations.html
that will put you with initial migration.
Conflicts occurring in migration files, Is it needed to commit the migration files or not? Is it needed to run makemigrations? (python,django 2.11)
Migrations are code. They must be in the repository. Don't generate migrations on server. On your developer machine only and don't forget to commit them. It's important to follow the rule: each commit that contains any model changes must contains appropriate migrations. Then when deploying you need to apply ones.
In other words, when someone pulls your code and runs manage.py makemigrations he or she doesn't produce any new migarions.
As of now, I'm using django 2. In dev we won't commit any migration files. We put the migration folder to gitignore, so that we won't commit.
When our code is pulled to production, they run makemigrations command, so that there won't be any migration issue.
With this production will have only one file for a model, where as in dev we may have multiple migration files same modal
I am not sure what you mean by production, but there is need to commit migrations. And you always need to run makemigrations before you migrate (if you are making changes to your model). And if there is any error, you might have to clearly state here.
I just cloned a large django project and if I run the migrations I get errors. I wanted to know if it's necessary to go into each migration file and fix it, or to somehow skip them. I know in rails that in a situation like this one is advised to load the schema instead of running all of the past migrations, and wondered if it was the same for django. I know that one option is to delete all of the migrations, but since I am on a team that already has their local databases set up, I cant commit a deletion of all the migrations for my whole team, just so I can migrate my local database. How do I migrate my new local database given there are tons of migrations with tons of bugs and I mustn't delete the migration files for my git repo?
I have accidently deleted one of migrations folders and and have no backup for it.
What are my options?
DB is postgres. Right now everything is OK.(I have moved instead migration folder I have on my DEV server with SQL lite) So I am just getting red message on server that not all migrations have been applied.
But next time if i run migration i will be in trouble.
What is my way out?
Migrations are mainly for backward compatibility, and tracking/versioning of the changes to models/database. If you do not really care about historical changes, etc.. then you can just delete the migrations directory and do:
python manage.py makemigrations <app_name>
This creates the initial migrations (like starting from a clean slate) - and moving forward you can track the historical migrations moving forward. More on this can be read here
Now, when you run the migrations, you can do
python manage.py migrate <app_name> --fake-initial
to fake the initial migration.
Now might be a good time to have a version control on your application
Use version control.
You are not the first developer to delete important files, but often recovery takes less than a second - thanks to version control systems (also called revision control systems). Please stop everything else and install and use one of Git, Mercury or Subversion.
Don't use FTP
It's totally. I mean totally insecure. Always use SFTP
Don't use sqlite3 for local with other db for production
sqlite doesn't enforce strict type checking. Postgresql on the other hand is very particular about it. Additionally sqlite only has a subset of the functionality that's found on postgresql. Last but not least different RDBMS have different intricacies. If you use one locally and another in production, there is always a chance that your code will break when you deploy to live
Managing without the migration files
This is not a big loss as long as your database is in sync with your models.
If you database is not in sync with your models, you can use
./manage.py inspectdb
to recreate local models that represent the actual structure in the db. Then you do makemigrations and migrate (as explained by karthik) on the generated models.
Then replace that with your live models and do the step again.