49 lines
1.3 KiB
Ruby
49 lines
1.3 KiB
Ruby
# frozen_string_literal: true
|
|
|
|
module ActiveStorage
|
|
# This is an abstract base class for analyzers, which extract metadata from blobs. See
|
|
# ActiveStorage::Analyzer::VideoAnalyzer for an example of a concrete subclass.
|
|
class Analyzer
|
|
attr_reader :blob
|
|
|
|
# Implement this method in a concrete subclass. Have it return true when given a blob from which
|
|
# the analyzer can extract metadata.
|
|
def self.accept?(blob)
|
|
false
|
|
end
|
|
|
|
# Implement this method in concrete subclasses. It will determine if blob analysis
|
|
# should be done in a job or performed inline. By default, analysis is enqueued in a job.
|
|
def self.analyze_later?
|
|
true
|
|
end
|
|
|
|
def initialize(blob)
|
|
@blob = blob
|
|
end
|
|
|
|
# Override this method in a concrete subclass. Have it return a Hash of metadata.
|
|
def metadata
|
|
raise NotImplementedError
|
|
end
|
|
|
|
private
|
|
# Downloads the blob to a tempfile on disk. Yields the tempfile.
|
|
def download_blob_to_tempfile(&block) # :doc:
|
|
blob.open tmpdir: tmpdir, &block
|
|
end
|
|
|
|
def logger # :doc:
|
|
ActiveStorage.logger
|
|
end
|
|
|
|
def tmpdir # :doc:
|
|
Dir.tmpdir
|
|
end
|
|
|
|
def instrument(analyzer, &block) # :doc:
|
|
ActiveSupport::Notifications.instrument("analyze.active_storage", analyzer: analyzer, &block)
|
|
end
|
|
end
|
|
end
|