add files to pcdm/works

1_basic_pcdm__add_file_example.rb

# -----------------------------------  PCDM example adding a file to an object ---------------------------------
require "hydra/pcdm"

obj1 = Hydra::PCDM::Object.create

file1 = File.open("war_and_peace.pdf","r")
pcdm_file = Hydra::PCDM::File.new
pcdm_file.content = file1

obj1.files << pcdm_file
obj1.save

2_basic_works__add_file_example.rb

# -----------------------------------  Works example doing the same thing ---------------------------------
require "hydra/works"

genfil1 = Hydra::Works::GenericFile::Base.create

file1 = File.open("war_and_peace.pdf","r")
Hydra::Works::UploadFileToGenericFile.call(genfil1, file1)

genfil1.save

3_works__add_file_plus_service_example.rb

# -------------------  Works example doing the same thing + calling additional services -------------------
require "hydra/works"

genfil1 = Hydra::Works::GenericFile::Base.create

additional_services = [Hydra::Works::GenerateThumbnail]

file1 = File.open("war_and_peace.pdf","r")
Hydra::Works::UploadFileToGenericFile.call(genfil1, file1, additional_services: additional_services)

genfil1.save

4_works__add_file_plus_multi_service_example.rb

# -------------------  Works example doing the same thing + calling additional services -------------------
# WHAT I EXPECTED BUT DOESN'T WORK
# --------------------------------
require "hydra/works"

genfil1 = Hydra::Works::GenericFile::Base.create

additional_services = [Hydra::Works::GenerateThumbnail,
                       Hydra::Works::ExtractFullText]

file1 = File.open("war_and_peace.pdf","r")
Hydra::Works::UploadFileToGenericFile.call(genfil1, file1, additional_services: additional_services)

genfil1.save

5_alternative_works__running_derivatives_example.rb

# -------------------  Works example doing the same thing calling derivatives outside upload -------------------
# WHAT I EXPECTED BUT DOESN'T WORK
# --------------------------------
require "hydra/works"

genfil1 = Hydra::Works::GenericFile::Base.create

additional_services = [Hydra::Works::GenerateThumbnail,
                       Hydra::Works::ExtractFullText]

file1 = File.open("war_and_peace.pdf","r")
Hydra::Works::UploadFileToGenericFile.call(genfil1, file1)

# create thumbnail - configured in models/concerns/generic_file/derivatives.rb#makes_derivatives
genfil1.create_derivatives

# create extracted text - Options:  
#   1) move this to hydra-derivatives and update #makes_derivatives to generate this for appropriate file types
#   2) create a service object where this is one call and can be passed as an additional service
extracted_text = Hydra::Works::FullTextExtractionService.run(generic_file)
generic_file.build_extracted_text
generic_file.extracted_text.content = extracted_text

# QUESTION: Can makes_derivatives be overriden by classes using Hydra::Works::GenericFile to customize a different 
# set of derivatives to generate.  models/concerns/generic_file/derivatives.rb#makes_derivatives becomes the default.

genfil1.save

👍 looks good to me

I would attach a thumbnail and extracted text like this based on the current code.

generic_file = Hydra::Works::GenericFile::Base.create
file = File.open("war_and_peace.pdf","r")
Hydra::Works::UploadFileToGenericFile.call(generic_file, file)
generic_file.create_derivatives

# This part isn't ideal - the service returns a string
extracted_text = Hydra::Works::FullTextExtractionService.run(generic_file)
generic_file.build_extracted_text
generic_file.extracted_text.content = extracted_text

There's a good example on the hydra-derivatives readme.

After attaching a file to a generic_file, call create_derivatives on it to create and attach associated derivatives. Processors and the derivative files/formats are configured by the makes_derivatives block. The derivatives processors create the derivative filestreams and then call the output service (here is an example of the image processor calling the output_file_service). The output service must conform to the signature documented here. It takes 3 arguments: a generic_file, filestream, and destination name symbol.

There are three output file services implemented, persist_derivative in Hydra::Works (a directly attached derivative), persist_basic_contained_output_file in Hydra::Derivatives, and persist_derivative in CurationConcerns (which writes derivatives to the filesystem).

I got the extracted_text bit from the CurationConcerns chracterization service