Testing: compatibility with -no-migrations mode

[benjaminrigaud]

When running pytest --no-migrations, Models are synced to their corresponding tables as-is: no migrations are executed.

django-db-views doesn't support this mode: the views are not created and the tests fail.

As a workaround, I have implemented a fixture to be able to apply any migration on the fly.

A proper implementation in django-db-views could be to uncouple the SQL creating the views from the migration framework: it would permit the creation of a few helper to execute this SQL outside of the migrations (django-pgtrigger does something like that).

What are your thoughts?

References:

• https://pytest-django.readthedocs.io/en/latest/database.html#no-migrations-disable-django-migrations
• https://django-pgtrigger.readthedocs.io/en/4.6.0/faq.html#how-do-i-test-triggers

[BezBartek]

@benjaminrigaud
Thank you for your thoughts
I will try to get deeper into it through the weekend

[benjaminrigaud]

Hi,

If I implement a fix, would you have time to review it? 🙇

Ben

[BezBartek]

Hello @benjaminrigaud
Please do so, thank you!
Apologize that I didn't find time to write it
I will review your code and merge

[lajus]

Hello,

I have run into the same issue while experimenting with django-db-views on my project.

@benjaminrigaud you said

As a workaround, I have implemented a fixture to be able to apply any migration on the fly.

would it be possible for you to share the code of your fixture ?

Thanks,
Jonathan

[benjaminrigaud]

would it be possible for you to share the code of your fixture ?

Sorry @lajus, I can't share that code from a private Repo.

Some details:

• It uses __import__ to import the migration module
• Then instantiates the Migration class from this module
• Then it calls migration.apply(...)

[stefanofusai]

Also interested in this

[BezBartek]

@stefanofusai @lajus
I will add this next week

[BezBartek]

@stefanofusai @lajus
I almost finish, it will take additional week cuz huge loads at my work currently

[stefanofusai]

Thank you so much! Let me know if I can be of help

[BezBartek]

@stefanofusai
check fixture that I added, it does work.

[stefanofusai]

@BezBartek thank you so much for your work but unfortunately it's not working for me :(

I'm getting errors when I remove the --no-migrations, likely due to incompatibility with factory-boy
Doing this: MyModelFactory.create() results in the following error:

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

self = <django.db.backends.postgresql.base.Cursor [closed] [IDLE] (host=... user=... database=...) at 0x7ff292c2b290>
query = 'INSERT INTO "myapp_mymodel" (...) VALUES (...) RETURNING "myapp_mymodel"."id"'
params = (...)

    def execute(
        self,
        query: Query,
        params: Params | None = None,
        *,
        prepare: bool | None = None,
        binary: bool | None = None,
    ) -> Self:
        """
        Execute a query or command to the database.
        """
        try:
            with self._conn.lock:
                self._conn.wait(
                    self._execute_gen(query, params, prepare=prepare, binary=binary)
                )
        except e._NO_TRACEBACK as ex:
>           raise ex.with_traceback(None)
E           django.db.utils.ProgrammingError: non è possibile modificare la vista materializzata "myapp_mymodel"

The error roughly translates to, in English: cannot modify the materialized view "myapp_mymodel".
Here is more code that may be relevant:

class MyModel(DBMaterializedView): # my materialized view model
    ...

    view_definition = ...
    
    class Meta:
        db_table = ...
        managed = False

class MyModelFactory(DjangoModelFactory): # my factory-boy factory
    class Meta:
        django_get_or_create = ...
        model = MyModel

    ...

# In my global conftest, I have to put this otherwise for some reason the models aren't created correctly in the database (even if running with --no-migrations)
# Not sure if this separate issue can also be looked into
def pytest_sessionstart() -> None: 
    MyModelFactory._meta.managed = True  # noqa: SLF001