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Provider selection

Providers.for_storage walks Config.enabled_providers in order and returns the first provider that supports the app's storage:

:s3 supports it only when the app's default ActiveStorage::Blob.service is an ActiveStorage::Service::S3Service (i.e. service: S3 in storage.yml).
:tus is storage-agnostic but is only available when Config::Tus.endpoint is configured.

Because the list is ordered, earlier entries win. [:s3, :tus] prefers S3 when the default service is S3-backed and falls back to tus otherwise; [:tus, :s3] prefers tus whenever it is configured.

Config.enabled_providers defaults to [], which disables chunked uploads entirely (file fields fall back to base64, fully backward compatible). An unknown provider name raises Eluvia::Errors::StandardError from Providers.validate_enabled_providers!, so a configuration typo fails loudly instead of silently disabling chunked upload.

When no enabled provider supports the app's storage (e.g. only :s3 is enabled but the default service is Disk), every field falls back to base64 and no upload block is emitted in its schema. The same happens if aws-sdk-s3 is not loaded (Providers::S3#supports_storage? returns false) even though :s3 is listed.

caution

Unlike the Python library, which resolves a provider per field against that field's own storage, Ruby habarico resolves a single provider for the whole app — Providers.for_storage takes no field-specific storage argument, both providers ignore the storage: keyword they are handed. A model with file fields on different storages does not get a provider chosen per field; all chunked-capable fields share whatever the app's one default service is.

See also​

See also