Class: MARC::ControlField

Inherits:
Object
  • Object
show all
Defined in:
lib/marc/controlfield.rb

Overview

MARC records contain control fields, each of which has a tag and value. Tags for control fields must be in the 001-009 range or be specially added to the @@control_tags Set

Constant Summary collapse

@@control_tags =

Initially, control tags are the numbers 1 through 9 or the string ‘000’

Set.new(%w[000 001 002 003 004 005 006 007 008 009])

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(tag, value = "") ⇒ ControlField

The constructor which must be passed a tag value and an optional value for the field.



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# File 'lib/marc/controlfield.rb', line 30

def initialize(tag, value = "")
  @tag = tag
  @value = value
end

Instance Attribute Details

#tag ⇒ Object

the tag value (007, 008, etc)



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# File 'lib/marc/controlfield.rb', line 22

def tag
  @tag
end

#value ⇒ Object

the value of the control field



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# File 'lib/marc/controlfield.rb', line 25

def value
  @value
end

Class Method Details

.control_tag?(tag) ⇒ Boolean

A tag is a control tag if tag.to_s is a member of the @@control_tags set.

Returns:

  • (Boolean) 


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# File 'lib/marc/controlfield.rb', line 17

def self.control_tag?(tag)
  @@control_tags.include? tag.to_s
end

.control_tags ⇒ Object 



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# File 'lib/marc/controlfield.rb', line 12

def self.control_tags
  @@control_tags
end

Instance Method Details

#==(other) ⇒ Object

Two control fields are equal if their tags and values are equal.



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# File 'lib/marc/controlfield.rb', line 53

def ==(other)
  if !other.is_a?(ControlField)
    return false
  end
  if @tag != other.tag
    return false
  elsif @value != other.value
    return false
  end
  true
end

#=~(regex) ⇒ Object 



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# File 'lib/marc/controlfield.rb', line 79

def =~(regex)
  to_s =~ regex
end

#errors ⇒ Object

Returns an array of validation errors



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# File 'lib/marc/controlfield.rb', line 41

def errors
  messages = []

  unless MARC::ControlField.control_tag?(@tag)
    messages << "tag #{@tag.inspect} must be in 001-009 or in the MARC::ControlField.control_tags set"
  end

  messages
end

#to_hash ⇒ Object

Turn the control field into a hash for MARC-in-JSON



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# File 'lib/marc/controlfield.rb', line 71

def to_hash
  {@tag => @value}
end

#to_marchash ⇒ Object

turning it into a marc-hash element



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# File 'lib/marc/controlfield.rb', line 66

def to_marchash
  [@tag, @value]
end

#to_s ⇒ Object 



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# File 'lib/marc/controlfield.rb', line 75

def to_s
  "#{tag} #{value}"
end

#valid? ⇒ Boolean

Returns true if there are no error messages associated with the field

Returns:

  • (Boolean) 


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# File 'lib/marc/controlfield.rb', line 36

def valid?
  errors.none?
end