How to prevent Django from generating migrations when using dynamic GoogleCloudStorage in a FileField?

Question

On my Django Project I have a model that a property is used to store videos in a specific and single Google Cloud Storage bucket, using FileField.

The model is defined like this:

from storages.backends.gcloud import GoogleCloudStorage
from django.conf import settings

DEFAULT_STORAGE = GoogleCloudStorage(bucket_name=settings.DEFAULT_GCS_BUCKET)

class Recording(models.Model):
    raw_file_gcp = models.FileField(blank=True, null=True, storage=DEFAULT_STORAGE)

The problem is that, there's a new architecture that we need to use in which a new storage comes into play... A second bucket, in which a video is transfereed from one bucket to another.

To do that, we dynamically update the .name attribute of the file whenever we need to move a file from one bucket to another, like this:

recording.raw_file_gcp.name = path_with_retention_bucket # Here we update on demand the secondary bucket path.
recording.save(update_fields=["raw_file_gcp", "updated_at"])

It's working and all, but, for some reason, every time the above rule is executed, the system keeps asking me to run a migration. And it generates a migration automatically...

This is the migration it generates, whenever the code above is executed:

migrations.AlterField(
    model_name='recording',
    name='raw_file_gcp',
    field=models.FileField(blank=True, null=True, storage=myapp.models.CustomStorage(bucket_name='default-bucket')),
)

But nothing has actually changed in the model...

To try avoiding this unnecessary AlterField migration, I implemented a custom storage class using @deconstructible and __eq__, like this:

from django.utils.deconstruct import deconstructible
from storages.backends.gcloud import GoogleCloudStorage

@deconstructible
class NeutralGCSStorage(GoogleCloudStorage):
    def __eq__(self, other):
        return isinstance(other, NeutralGCSStorage)

And on my storage definition I used this neutral gcs definition:

DEFAULT_STORAGE = NeutralGCSStorage(bucket_name=settings.DEFAULT_GCS_BUCKET)

But Django still generates the same migration. How can I prevent Django from generating migrations when the only difference is the dynamic storage bucket used in a FileField? The one we change it on demand...

So even if the bucket name remains the same, it generates a migration, or what do you mean with `"dynamic bucket logic"? — willeM_ Van Onsem
– willeM_ Van Onsem, Commented Jul 21 at 20:08
The migration you show uses CustomStorage by the way, not NeutralGCSStorage... — willeM_ Van Onsem
– willeM_ Van Onsem, Commented Jul 21 at 20:16
@willeM_VanOnsem yeah, we're just updating the file name at runtime to switch buckets, but django keeps detecting changes and generating alterfield migrations, even with eq overridden in a custom storage class. nothing in the model actually changed. any idea how to make django ignore this? — Raul Chiarella
– Raul Chiarella, Commented Jul 21 at 21:11
I think this answer should help you stackoverflow.com/a/79284440/16494437 — PTomasz
– PTomasz, Commented Jul 22 at 7:30
@PTomasz Nice. It's similar to another approach I was suggested to read as well: adamj.eu/tech/2025/05/03/… — Raul Chiarella
– Raul Chiarella, Commented Jul 22 at 18:52

PTomasz · Accepted Answer · 2025-10-31 07:36:58Z

1

In Django FileField you can choose function as source of the storage. In order to do that create new function

def default_google_cloud_storage():
    return GoogleCloudStorage(bucket_name=settings.DEFAULT_GCS_BUCKET)

and use it without calling as storage in your FileField

class Recording(models.Model):
    raw_file_gcp = models.FileField(
                          blank=True, 
                          null=True, 
                          storage=default_google_cloud_storage
                          )

answered Oct 31 at 7:36

PTomasz

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