Capabilities

To understand in advance whether specific storage can perform certain actions, ckanext-files uses ckanext.files.shared.Capability. It's an enumeration of operations that can be supported by storage:

Capability	Action performed by storage
CREATE	create a file as an atomic object
STREAM	return file content as stream of bytes
COPY	make a copy of the file inside the same storage
REMOVE	remove file from the storage
MULTIPART	create file in 3 stages: start, upload(repeatable), complete
MOVE	move file to a different location inside the same storage
EXISTS	check if file exists
SCAN	iterate over all files in the storage
APPEND	add content to the existing file
COMPOSE	combine multiple files into a new one in the same storage
RANGE	return specific range of bytes from the file
ANALYZE	return file details from the storage, as if file was uploaded just now
PERMANENT_LINK	make permanent download link for private file
TEMPORAL_LINK	make expiring download link for private file
ONE_TIME_LINK	make one-time download link for private file
PUBLIC_LINK	make permanent public link

These capabilities are defined when storage is created and are automatically checked by actions that work with storage. If you want to check if storage supports certain capability, it can be done manually. If you want to check presence of multiple capabilities at once, you can combine them via bitwise-or operator.

from ckanext.files.shared import Capability, get_storage

storage = get_storage()

can_read = storage.supports(Capability.STREAM)

read_and_write = Capability.CREATE | Capability.STREAM
can_read_and_write = storage.supports(read_and_write)

ckan files storages -v CLI command lists all configured storages with their capabilities.