我应该在.gitignore文件中添加Django迁移文件吗？

Should I be adding the Django migration files in the .gitignore file?

I’ve recently been getting a lot of git issues due to migration conflicts and was wondering if I should be marking migration files as ignore.

If so, how would I go about adding all of the migrations that I have in my apps, and adding them to the .gitignore file?

Quoting from the Django migrations documentation:

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.

If you follow this process, you shouldn’t be getting any merge conflicts in the migration files.

When merging version control branches, you still may encounter a situation where you have multiple migrations based on the same parent migration, e.g. if to different developers introduced a migration concurrently. One way of resolving this situation is to introduce a _merge_migration_. Often this can be done automatically with the command

./manage.py makemigrations --merge

which will introduce a new migration that depends on all current head migrations. Of course this only works when there is no conflict between the head migrations, in which case you will have to resolve the problem manually.

Given that some people here suggested that you shouldn’t commit your migrations to version control, I’d like to expand on the reasons why you actually should do so.

First, you need a record of the migrations applied to your production systems. If you deploy changes to production and want to migrate the database, you need a description of the current state. You can create a separate backup of the migrations applied to each production database, but this seems unnecessarily cumbersome.

Second, migrations often contain custom, handwritten code. It’s not always possible to automatically generate them with ./manage.py makemigrations.

Third, migrations should be included in code review. They are significant changes to your production system, and there are lots of things that can go wrong with them.

So in short, if you care about your production data, please check your migrations into version control.

You can follow the below process.

You can run makemigrations locally and this creates the migration file. Commit this new migration file to repo.

In my opinion you should not run makemigrations in production at all. You can run migrate in production and you will see the migrations are applied from the migration file that you committed from local. This way you can avoid all conflicts.

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

Quote from the 2018 docs, Django 2.0. (two separate commands = makemigrations and migrate)

The reason that there are separate commands to make and apply migrations is because you’ll commit migrations to your version control system and ship them with your app; they not only make your development easier, they’re also useable by other developers and in production.

https://docs.djangoproject.com/en/2.0/intro/tutorial02/

TL;DR: commit migrations, resolve migration conflicts, adjust your git workflow.

Feels like you’d need to adjust your git workflow, instead of ignoring conflicts.

Ideally, every new feature is developed in a different branch, and merged back with a pull request.

PRs cannot be merged if there’s a conflict, therefore who needs to merge his feature needs to resolve the conflict, migrations included. This might need coordination between different teams.

It is important though to commit migration files! If a conflict arises, Django might even help you solve those conflicts ;)

I can’t imagine why you would be getting conflicts, unless you’re editing the migrations somehow? That usually ends badly – if someone misses some intermediate commits then they won’t be upgrading from the correct version, and their copy of the database will be corrupted.

The process that I follow is pretty simple – whenever you change the models for an app, you also commit a migration, and then that migration doesn’t change – if you need something different in the model, then you change the model and commit a new migration alongside your changes.

In greenfield projects, you can often delete the migrations and start over from scratch with a 0001_ migration when you release, but if you have production code, then you can’t (though you can squash migrations down into one).

The solution usually used, is that, before anything is merged into master, the developer must pull any remote changes. If there’s a conflict in migration versions, he should rename his local migration (the remote one has been run by other devs, and, potentially, in production), to N+1.

During development it might be okay to just not-commit migrations (don’t add an ignore though, just don’t add them). But once you’ve gone into production, you’ll need them in order to keep the schema in sync with model changes.

You then need to edit the file, and change the dependencies to the latest remote version.

This works for Django migrations, as well as other similar apps (sqlalchemy+alembic, RoR, etc).

Having a bunch of migration files in git is messy. There is only one file in migration folder that you should not ignore. That file is init.py file, If you ignore it, python will no longer look for submodules inside the directory, so any attempts to import the modules will fail. So the question should be how to ignore all migration files but init.py? The solution is: Add ‘0*.py’ to .gitignore files and it does the job perfectly.

Hope this helps someone.

Gitignore the migrations, if You have separate DBs for Development, Staging and Production environment. For dev. purposes You can use local sqlite DB and play with migrations locally. I would recommend You to create four additional branches:

1. Master – Clean fresh code without migrations. Nobody is connected to this branch. Used for code reviews only

2. Development – daily development. Push/pull accepted. Each developer is working on sqlite DB

3. Cloud_DEV_env – remote cloud/server DEV environment. Pull only. Keep migrations locally on machine, which is used for the code deployment and remote migrations of Dev database

4. Cloud_STAG_env – remote cloud/server STAG environment. Pull only. Keep migrations locally on machine, which is used for the code deployment and remote migrations of Stag database

5. Cloud_PROD_env – remote cloud/server DEV environment. Pull only. Keep migrations locally on machine, which is used for the code deployment and remote migrations of Prod database

Notes: 2, 3, 4 – migrations can be kept in repos but there should be strict rules of pull requests merging, so we decided to find a person, responsible for deployments, so the only guy who has all the migration files – our deploy-er. He keeps the remote DB migrations each time we have any changes in Models.

Short answer I propose excluding migrations in the repo. After code merge, just run ./manage.py makemigrations and you are all set.

Long answer I don’t think you should put migrations files into repo. It will spoil the migration states in other person’s dev environment and other prod and stage environment. (refer to Sugar Tang’s comment for examples).

In my point of view, the purpose of Django migrations is to find gaps between previous model states and new model states, and then serialise the gap. If your model changes after code merge, you can simple do makemigrations to find out the gap. Why do you want to manually and carefully merge other migrations when you can achieve the same automatically and bug free? Django documentation says,

They*(migrations)*’re designed to be mostly automatic

; please keep it that way. To merge migrations manually, you have to fully understand what others have changed and any dependence of the changes. That’s a lot of overhead and error prone. So tracking models file is sufficient.

It is a good topic on the workflow. I am open to other options.