Why there is need to push django migrations to ver

问题:

This is a common practice that people working on django project usually push migrations to the version control system along with other code.

My question is why this practice is so common? Why not just push the updated models and everyone generate migrations locally. This approach can reduce the effort for resolving migrations conflicts too.

回答1:

If you didn't commit them to a VCS then what would happen is people would make potentially conflicting changes to the model.

When finally ready to deploy, you would still need django to make new migrations that would then merge everybodys changes together. And this just creates an additional unnecessary step that can introduce bugs.

You also are assuming everybody will always be able to work on an up to date version of the code which isn't always possible when you start working on branches that are not ready to be merged into mainline.

回答2:

Migrations synchronize the state of your database with the state of your code. If you don't check in the migrations into version control, you lose the intermediate steps. You won't be able to go back in the version control history and just run the code, as the database won't match the models at that point in time.

Migrations, like any code, should be tested, at the very least on a basic level. Even though they are auto-generated, that's not a guarantee that they will work 100% of the time. So the safe path is to create the migrations in your development environment, test them, and then push them to the production environment to apply them there.

回答3:

Firstly, migrations in version control allows you to run them in production.

Secondly, migrations are not always automatically generated. For example, if you add a new field to a model, you might write a migration to populate the field. That migration cannot be re-created from the models. If that migration is not in version control, then no-one else will be able to run it.