Module: OcflTools::Utils::Inventory

Defined in:
lib/ocfl_tools/utils_inventory.rb

Overview

A module of convenience methods for reading information from an OCFL inventory.json file. Inventory.get_value and its children are designed to account for reading info from the top few lines of a potentially many-MB size file, without having to load it all into memory by ingesting it with OcflInventory.

Class Method Summary collapse

Class Method Details

.get_contentDirectory(inventory_file) ⇒ String

Given an inventory file, return the value of contentDirectory IF FOUND, or ‘content’ if contentDirectory is not set. It explicitly does NOT use the config.content_directory setting for this check.

Parameters:

  • inventory_file (Pathname) —

    fully-qualified path to a valid OCFL inventory.json.

Returns:

  • (String) —

    the value of content_directory in the JSON, if found, or the OCFL required default value of ‘content’.



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# File 'lib/ocfl_tools/utils_inventory.rb', line 41

def self.get_contentDirectory(inventory_file)
  contentDirectory = OcflTools::Utils::Inventory.get_value(inventory_file, 'contentDirectory')
  contentDirectory = 'content' if contentDirectory.nil?
  contentDirectory
end

.get_digestAlgorithm(inventory_file) ⇒ String

Given an inventory file, return the name of the digest algorithm used (e.g. ‘sha512’).

Parameters:

  • inventory_file (Pathname) —

    fully-qualified path to a valid OCFL inventory.json.

Returns:

  • (String) —

    the string value describing the digest algorithm used in this inventory.



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# File 'lib/ocfl_tools/utils_inventory.rb', line 50

def self.get_digestAlgorithm(inventory_file)
  digestAlgorithm = OcflTools::Utils::Inventory.get_value(inventory_file, 'digestAlgorithm')
  if digestAlgorithm.nil?
    # Actually against OCFL spec
    raise "Unable to find value for digestAlgorithm in #{inventory_file}"
  end

  digestAlgorithm
end

.get_fixity(inventory_file) ⇒ Hash or nil

Given an inventory file, return the fixity block (if it exists) or nil.

Parameters:

  • inventory_file (Pathname) —

    fully-qualified path to a valid OCFL inventory.json.

Returns:

  • (Hash or nil) —

    the fixity block from the provided inventory.json, or nil if the inventory does not contain a fixity block.



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# File 'lib/ocfl_tools/utils_inventory.rb', line 63

def self.get_fixity(inventory_file)
  inventory = OcflTools::OcflInventory.new.from_file(inventory_file)
  return nil if inventory.fixity.empty?

  inventory.fixity
end

.get_fixity_digestAlgorithms(inventory_file) ⇒ Array or nil

Given an inventory file, return [Array] of the digest types found in the fixity block, or nil.

Parameters:

  • inventory_file (Pathname) —

    fully-qualified path to a valid OCFL inventory.json.

Returns:

  • (Array or nil) —

    an array of [String] values, with each value being a digest type found in the fixity block, e.g. ‘sha1’, ‘md5’, etc, or nil if no fixity block is found.



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# File 'lib/ocfl_tools/utils_inventory.rb', line 73

def self.get_fixity_digestAlgorithms(inventory_file)
  inventory = OcflTools::OcflInventory.new.from_file(inventory_file)
  return nil if inventory.fixity.empty?

  inventory.fixity.keys
end

.get_fixity_digests(inventory_file, digestAlgorithm) ⇒ Hash or nil

Given an inventory file and a digestAlgorithm, return [Hash] of digests and [ filepaths ], or nil.

Parameters:

  • inventory_file (Pathname) —

    fully-qualified path to a valid OCFL inventory.json.

  • digestAlgorithm (String) —

    the algorithm used in the fixity block that you want digests for.

Returns:

  • (Hash or nil) —

    a hash of digests and filepaths from the fixity block for the given digest type, or nil if the inventory.json does not contain a fixity block.



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# File 'lib/ocfl_tools/utils_inventory.rb', line 84

def self.get_fixity_digests(inventory_file, digestAlgorithm)
  inventory = OcflTools::OcflInventory.new.from_file(inventory_file)
  return nil if inventory.fixity.empty?

  inventory.fixity[digestAlgorithm]
end

.get_value(inventory_file, key) ⇒ String or nil

Given an inventory file and a key to search for, return the value at that key.

Parameters:

  • inventory_file (Pathname) —

    fully-qualified path to a valid OCFL inventory.json.

  • key (String) —

    the JSON key in the inventory file that you want to return a value for.

Returns:

  • (String or nil) —

    the value of the requested key, or nil if not found.



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# File 'lib/ocfl_tools/utils_inventory.rb', line 13

def self.get_value(inventory_file, key)
  unless %w[contentDirectory digestAlgorithm head type id].include?(key)
    raise OcflTools::Errors::RequestedKeyNotFound, "#{key} is not a valid OCFL inventory header key"
  end

  inventory = OcflTools::OcflInventory.new.from_file(inventory_file)

  case key
    when 'contentDirectory'
      inventory.contentDirectory
    when 'digestAlgorithm'
      inventory.digestAlgorithm
    when 'head'
      inventory.head
    when 'type'
      inventory.type
    when 'id'
      inventory.id
    else
      raise "Unknown key #{key}"
  end

end