Module: Tripod::Attributes

Extended by:
ActiveSupport::Concern
Included in:
Components, EmbeddedResource
Defined in:
lib/tripod/attributes.rb

Overview

This module defines behaviour for attributes.

Instance Method Summary collapse

Instance Method Details

#read_attribute(name, field = nil) ⇒ Object Also known as: []

Reads an attribute from this resource, based on a defined field Returns the value(s) for the named (or given) field

Examples:

Read the value associated with a predicate.

class Person
  field :name, 'http://name'
end

person.read_attribute(:name)

Parameters:

  • name (String) —

    The name of the field for which to get the value.

  • field (Field) (defaults to: nil) —

    An optional Field object

Returns:

  • Native Ruby object (e.g. String, DateTime) or array of them, depending on whether the field is multivalued or not



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# File 'lib/tripod/attributes.rb', line 22

def read_attribute(name, field=nil)
  field ||= self.class.get_field(name)

  attr_values = read_predicate(field.predicate)

  if field.multivalued
    # If the field is multivalued, return an array of the results
    # just return the uri or the value of the literal.
    attr_values.map { |v| field.is_uri? ? v :  v.object }
  else
    # If it's not multivalued, return the first (should be only) result.
    if field.is_uri?
      attr_values.first
    else
      # try to get it in english if it's there. (TODO: make it configurable what the default is)
      val = attr_values.select{ |v| v.language == :en }.first || attr_values.first
      val.object if val
    end
  end
end

#write_attribute(name, value, field = nil) ⇒ Object Also known as: []=

Writes an attribute to the resource, based on a defined field

Examples:

Write the value associated with a predicate.

class Person
  field :name, 'http://name'
end

person.write_attribute(:name, 'Bob')

Parameters:

  • name (String) —

    The name of the field for which to set the value.

  • value (String) —

    The value to set it to

  • field (Field) (defaults to: nil) —

    An optional Field object

Raises:



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# File 'lib/tripod/attributes.rb', line 56

def write_attribute(name, value, field=nil)
  field ||= self.fields[name]
  raise Tripod::Errors::FieldNotPresent.new unless field

  if value.kind_of?(Array)
    if field.multivalued
      new_val = []
      value.each do |v|
        new_val << write_value_for_field(v, field)
      end
    else
      new_val = write_value_for_field(value.first, field)
    end
  else
    new_val = write_value_for_field(value, field)
  end

  attribute_will_change!(name)
  write_predicate(field.predicate, new_val)
end