Class: Dor::TechnicalMetadataService

Inherits:
Object
  • Object
show all
Defined in:
lib/dor/services/technical_metadata_service.rb

Overview

Extracts technical metadata from files using JHOVE If this is a new version it gets the old technicalMetadata datastream by making an API call to sdr-services-app (via dor-services-app) and only overwrites/adds parts for the files that were changed or added. This allows us to avoid re-staging files that have not changed. Switching to a more granular data model that has file metadata separate from the Work metadata will allow us to simplify this greatly.

Class Method Summary collapse

Class Method Details

.add_update_technical_metadata(dor_item) ⇒ Boolean

Returns True if technical metadata is correctly added or updated.

Parameters:

  • dor_item (Dor::Item) —

    The DOR item being processed by the technical metadata robot

Returns:

  • (Boolean) —

    True if technical metadata is correctly added or updated



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# File 'lib/dor/services/technical_metadata_service.rb', line 19

def self.add_update_technical_metadata(dor_item)
  test_jhove_service
  druid = dor_item.pid
  content_group_diff = get_content_group_diff(dor_item)
  deltas = get_file_deltas(content_group_diff)
  new_files = get_new_files(deltas)
  old_techmd = get_old_technical_metadata(dor_item)
  new_techmd = get_new_technical_metadata(druid, new_files)
  if old_techmd.nil?
    # this is version 1 or previous technical metadata was not saved
    final_techmd = new_techmd
  elsif content_group_diff.difference_count == 0
    # there have been no changes to content files from previous version
    return true
  else
    merged_nodes = merge_file_nodes(old_techmd, new_techmd, deltas)
    final_techmd = build_technical_metadata(druid, merged_nodes)
  end
  ds = dor_item.datastreams['technicalMetadata']
  ds.dsLabel = 'Technical Metadata'
  ds.content = final_techmd
  ds.save
  true
end