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rails--rails/activestorage/app/models/active_storage/blob/analyzable.rb
2020-01-16 14:14:28 -05:00

61 lines
2.4 KiB
Ruby

# frozen_string_literal: true
require "active_storage/analyzer/null_analyzer"
module ActiveStorage::Blob::Analyzable
# Extracts and stores metadata from the file associated with this blob using a relevant analyzer. Active Storage comes
# with built-in analyzers for images and videos. See ActiveStorage::Analyzer::ImageAnalyzer and
# ActiveStorage::Analyzer::VideoAnalyzer for information about the specific attributes they extract and the third-party
# libraries they require.
#
# To choose the analyzer for a blob, Active Storage calls +accept?+ on each registered analyzer in order. It uses the
# first analyzer for which +accept?+ returns true when given the blob. If no registered analyzer accepts the blob, no
# metadata is extracted from it.
#
# In a Rails application, add or remove analyzers by manipulating +Rails.application.config.active_storage.analyzers+
# in an initializer:
#
# # Add a custom analyzer for Microsoft Office documents:
# Rails.application.config.active_storage.analyzers.append DOCXAnalyzer
#
# # Remove the built-in video analyzer:
# Rails.application.config.active_storage.analyzers.delete ActiveStorage::Analyzer::VideoAnalyzer
#
# Outside of a Rails application, manipulate +ActiveStorage.analyzers+ instead.
#
# You won't ordinarily need to call this method from a Rails application. New blobs are automatically and asynchronously
# analyzed via #analyze_later when they're attached for the first time.
def analyze
update! metadata: metadata.merge(extract_metadata_via_analyzer)
end
# Enqueues an ActiveStorage::AnalyzeJob which calls #analyze, or calls #analyze inline based on analyzer class configuration.
#
# This method is automatically called for a blob when it's attached for the first time. You can call it to analyze a blob
# again (e.g. if you add a new analyzer or modify an existing one).
def analyze_later
if analyzer_class.analyze_later?
ActiveStorage::AnalyzeJob.perform_later(self)
else
analyze
end
end
# Returns true if the blob has been analyzed.
def analyzed?
analyzed
end
private
def extract_metadata_via_analyzer
analyzer.metadata.merge(analyzed: true)
end
def analyzer
analyzer_class.new(self)
end
def analyzer_class
ActiveStorage.analyzers.detect { |klass| klass.accept?(self) } || ActiveStorage::Analyzer::NullAnalyzer
end
end