How to support multiple Google Cloud Storage buckets in a Django FileField without breaking .url resolution?
I'm using Django with django-storages and GoogleCloudStorage backend.
My model has a FileField like this:
raw_file_gcp = models.FileField(storage=GoogleCloudStorage(bucket_name='videos-raw'))
At runtime, I copy the file to a different bucket (e.g. 'videos-retention') using the GCS Python SDK:
source_blob = default_bucket.blob(name)
default_bucket.copy_blob(source_blob, retention_bucket, name)
After copying, I update the .name field:
recording.raw_file_gcp.name = f'videos-retention/{name}'
recording.save()
Everything works until I restart the app.
Then, when I access .url, Django tries to build the URL using the original bucket from the storage=... argument, even if the file now belongs to another bucket.
It ends up generating invalid URLs like:
https://storage.googleapis.com/videos-raw/https%3A/storage.cloud.google.com/videos-retention/filename.mp4
I expected Django to keep working even if the file was moved to a different bucket.
After debugging, I realized that the FileField is tightly coupled to the bucket used when the model is initialized. If the file moves to another bucket, .url breaks.
ChatGPT suggested removing FileField altogether, using a CharField instead, and dynamically resolving the GCS bucket + path in a custom @property using google.cloud.storage.blob.generate_signed_url().
Is there a better solution for this?
How can I support multiple GCS buckets dynamically with Django FileField?
Instead of relying on .url which seemed to be tied to the initial GCS bucket, you can use the google cloud storage SDK to fetch the url directly from the storage backend itself. The method blob.public_url can generate a valid url for the file even if it has been copied or moved to another bucket. However, private files require signed urls so use blob.generate_signed_url as an alternative.