Class: IiifPrint::PluggableDerivativeService

Inherits:
Object
  • Object
show all
Defined in:
app/services/iiif_print/pluggable_derivative_service.rb

Overview

General derivative service for IiifPrint, which is meant to wrap

and replace the stock Hyrax::FileSetDerivativeService with a proxy
that runs one or more derivative service "plugin" components.

Note: Hyrax::DerivativeService consumes this, instead of (directly)
consuming Hyrax::FileSetDerivativeService.

Unlike the "run the first valid plugin" arrangement that the
Hyrax::DerivativeService uses to run an actual derivative creation
service component, this component is:

(a) Consumed by Hyrax::DerivativeService as that first valid plugin;

(b) Wraps and runs 0..* plugins, not just the first.

This should be registered to take precedence over default by:

Hyrax::DerivativeService.services.unshift(
  IiifPrint::PluggableDerivativeService
)

Modify IiifPrint::PluggableDerivativeService.plugins
to add, remove, or reorder plugin (derivative service) classes.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(file_set, plugins: plugins_for(file_set)) ⇒ PluggableDerivativeService

Returns a new instance of PluggableDerivativeService.



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# File 'app/services/iiif_print/pluggable_derivative_service.rb', line 29

def initialize(file_set, plugins: plugins_for(file_set))
  @file_set = file_set
  @plugins = Array.wrap(plugins)
  @valid_plugins = plugins.map { |plugin| plugin.new(file_set) }.select(&:valid?)
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(method_name, *args, **opts, &block) ⇒ Object (private) 



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# File 'app/services/iiif_print/pluggable_derivative_service.rb', line 61

def method_missing(method_name, *args, **opts, &block)
  if allowed_methods.include?(method_name)
    # we have an allowed method, construct services and include all valid
    #   services for the file_set
    # services = plugins.map { |plugin| plugin.new(file_set) }.select(&:valid?)
    # run all valid services, in order:
    services(method_name).each do |plugin|
      plugin.send(method_name, *args, **opts, &block)
    end
  else
    super
  end
end

Instance Attribute Details

#file_set ⇒ Object (readonly)

Returns the value of attribute file_set.



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# File 'app/services/iiif_print/pluggable_derivative_service.rb', line 35

def file_set
  @file_set
end

#plugins ⇒ Object (readonly)

Returns the value of attribute plugins.



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# File 'app/services/iiif_print/pluggable_derivative_service.rb', line 35

def plugins
  @plugins
end

#valid_plugins ⇒ Object (readonly)

Returns the value of attribute valid_plugins.



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# File 'app/services/iiif_print/pluggable_derivative_service.rb', line 35

def valid_plugins
  @valid_plugins
end

Instance Method Details

#services(method_name) ⇒ Object

get derivative services relevant to method name and file_set context

-- omits plugins if particular destination exists or will soon.



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# File 'app/services/iiif_print/pluggable_derivative_service.rb', line 47

def services(method_name)
  valid_plugins.select do |plugin|
    dest = nil
    dest = plugin.target_extension if plugin.respond_to?(:target_extension)
    !skip_destination?(method_name, dest)
  end
end

#valid? ⇒ Boolean

this wrapper/proxy/composite is always valid, but it may compose

multiple plugins, some of which may or may not be valid, so
validity checks happen within as well.

Returns:

  • (Boolean) 


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# File 'app/services/iiif_print/pluggable_derivative_service.rb', line 41

def valid?
  !valid_plugins.empty?
end