Customizing Metadata

Table of Contents

• Override the GenericFile model
  • Add the property
  • Field repeatability
  • Try the property at the Rails console
• Extend the presenter
  • Required fields
  • Set the controller to use our presenter
• Create edit forms
  • Set the controllers to use our forms
• Labels and help text

Override the GenericFile model

The GenericFile class is provided by Sufia, but we want to update the model with our own metadata so we define it in our app to override what Sufia provides. Since Rails finds the class in our local application, it won't load it from Sufia.

# app/models/generic_file.rb
class GenericFile < ActiveFedora::Base
  include Sufia::GenericFile
end

Add the property

Add the property declaration into the GenericFile class (and pass a block to make sure the property is indexed in Solr):

  property :alternative, predicate: ::RDF::DC.alternative do |index|
    index.as :stored_searchable, :facetable
  end

When you're done the file should look like this:

# app/models/generic_file.rb
class GenericFile < ActiveFedora::Base
  include Sufia::GenericFile

  property :alternative, predicate: ::RDF::DC.alternative do |index|
    index.as :stored_searchable, :facetable
  end
end

Field repeatability

By default, properties are repeatable. If you want the property to be single-valued rather than repeatable, then you would add multiple: false to its property definition, as follows:

  property :alternative, predicate: ::RDF::DC.alternative, multiple: false do |index|
    index.as :stored_searchable, :facetable
  end

Try the property at the Rails console

You can try using the new property at the rails console like this. I've shown the expected output after each command.

$ rails c
Loading development environment (Rails 4.1.8)
irb(main):001:0> f = GenericFile.new(id: 'test-1')
  LocalAuthority Load (1.2ms)  SELECT  "local_authorities".* FROM "local_authorities"  WHERE "local_authorities"."name" = 'lc_subjects' LIMIT 1
  LocalAuthority Load (1.4ms)  SELECT  "local_authorities".* FROM "local_authorities"  WHERE "local_authorities"."name" = 'lexvo_languages' LIMIT 1
  LocalAuthority Load (1.3ms)  SELECT  "local_authorities".* FROM "local_authorities"  WHERE "local_authorities"."name" = 'lc_genres' LIMIT 1
ActiveFedora: loading fedora config from /opt/sufia/config/fedora.yml
ActiveFedora: loading solr config from /opt/sufia/config/solr.yml
Attempted to init base path `dev`, but it already exists
=> #<GenericFile id: "test-1", mime_type: "", format_label: [""], file_size: [""], last_modified: [""], filename: [""], original_checksum: [""], rights_basis: [], copyright_basis: [], copyright_note: [], well_formed: [], valid: [""], status_message: [], file_title: [""], file_author: [""], page_count: [""], file_language: [], word_count: [], character_count: [], paragraph_count: [], line_count: [], table_count: [], graphics_count: [], byte_order: [], compression: [], color_space: [], profile_name: [], profile_version: [], orientation: [], color_map: [], image_producer: [], capture_device: [], scanning_software: [], exif_version: [], gps_timestamp: [], latitude: [], longitude: [], character_set: [], markup_basis: [], markup_language: [], bit_depth: [], channels: [], data_format: [], offset: [], frame_rate: [], label: nil, depositor: nil, relative_path: nil, import_url: nil, part_of: [], resource_type: [], title: [], creator: [], contributor: [], description: [], tag: [], rights: [], publisher: [], date_created: [], date_uploaded: nil, date_modified: nil, subject: [], language: [], identifier: [], based_near: [], related_url: [], bibliographic_citation: [], source: [], proxy_depositor: nil, on_behalf_of: nil, alternative: [], batch_id: nil>
irb(main):002:0> f.alternative = ["An alternative title"]
=> ["An alternative title"]
irb(main):003:0> puts f.resource.dump(:ttl)

<http://127.0.0.1:8983/fedora/rest/dev/te/st/-1/test-1> <http://purl.org/dc/terms/alternative> "An alternative title";
   <info:fedora/fedora-system:def/model#hasModel> "GenericFile" .
=> nil
irb(main):004:0>

Extend the presenter

Sufia provides default presenter classes to control what properties of a model are display in your app, and in what order they appear. We create a subclass of Sufia's presenter adding alternative to the list of terms.

# app/presenters/my_generic_file_presenter.rb
class MyGenericFilePresenter < Sufia::GenericFilePresenter
  self.terms = [:resource_type, :title, :creator, :contributor, :description,
                :tag, :rights, :publisher, :date_created, :subject, :language,
                :identifier, :based_near, :related_url, :alternative]
end

Set the controller to use our presenter

Now we override Sufia's GenericFilesController so that it uses the MyGenericFilePresenter class that we defined rather than the default presenter in Sufia.

# app/controllers/generic_files_controller.rb
class GenericFilesController < ApplicationController
  include Sufia::Controller
  include Sufia::FilesControllerBehavior

  self.presenter_class = MyGenericFilePresenter
end

The fields show up in the show view of our app, but we also want them on our edit form too. Let's create an edit form that has our new field.

Create edit forms

Sufia also provides default form classes to control what properties of a model are editable in your app, and in what order they appear. Form classes extend presenter classes to include permissions and required fields, so we can base this work on what we already did with MyGenericFilePresenter. We subclass our own custom presenter to pick up the changes we already made there.

# app/forms/my_file_edit_form.rb
class MyFileEditForm < MyGenericFilePresenter
  include HydraEditor::Form
  include HydraEditor::Form::Permissions
end

On initial upload, Sufia allows users to edit metadata in bulk using a batch edit form, so we need to create a second form to be used by the BatchController.

# app/forms/my_batch_edit_form.rb
class MyBatchEditForm < MyFileEditForm
end

Required fields

We can also give MyFileEditForm a different set of required and non-required fields to override what it inherits from Sufia's GenericFilePresenter class:

# app/forms/my_file_edit_form.rb
class MyFileEditForm < MyGenericFilePresenter
  include HydraEditor::Form
  include HydraEditor::Form::Permissions

  self.required_fields = [:title, :alternative, :creator, :tag, :rights]
end

In theory, we can give MyBatchEditForm its own required_fields value to override the value it inherits from MyFileEditForm, but this might be something to think twice before doing.

Set the controllers to use our forms

Now we override Sufia's GenericFilesController and BatchController so that they use our custom edit form classes rather than the defaults in Sufia.

Add the following line to app/controllers/generic_files_controller.rb

  self.edit_form_class = MyFileEditForm

The whole file should look like this:

# app/controllers/generic_files_controller.rb
class GenericFilesController < ApplicationController
  include Sufia::Controller
  include Sufia::FilesControllerBehavior

  self.presenter_class = MyGenericFilePresenter
  self.edit_form_class = MyFileEditForm
end

And add the following line to app/controllers/batch_controller.rb

  self.edit_form_class = MyBatchEditForm

The whole file should look like this:

# app/controllers/batch_controller.rb
class BatchController < ApplicationController
  include Sufia::BatchControllerBehavior

  self.edit_form_class = MyBatchEditForm
end

The batch edits controller was not modified to allow you to set a form the way the batch controller was. (Batch edits are for editing from the dashboard; batch is about uploading groups of files together). So you have to override #terms directly. Add app/controllers/batch_edits_controller.rb:

class BatchEditsController < ApplicationController
  include Hydra::BatchEditBehavior
  include GenericFileHelper
  include Sufia::BatchEditsControllerBehavior

  def terms
    MyBatchEditForm.terms
  end
end

It would be nice to make things more consistent here; note this may all be overhauled soon due to pcdm.

Labels and help text

By default the label for the field in the form is taken from the property label, with the initial letter capitalised. Here is an example of customising it, and the associated help text:

# config/locales/sufia.en.yml
en:
  simple_form:
    labels:
      generic_file:
        alternative: "Alternative Title"
    metadata_help:
      generic_file:
        alternative: "An alternative name for a file."