ruby--ruby/doc/csv/options/parsing/converters.rdoc

====== Option +converters+

Specifies converters to be used in parsing fields.
See {Field Converters}[#class-CSV-label-Field+Converters]

Default value:
  CSV::DEFAULT_OPTIONS.fetch(:converters) # => nil

The value may be a field converter name
(see {Stored Converters}[#class-CSV-label-Stored+Converters]):
  str = '1,2,3'
  # Without a converter
  array = CSV.parse_line(str)
  array # => ["1", "2", "3"]
  # With built-in converter :integer
  array = CSV.parse_line(str, converters: :integer)
  array # => [1, 2, 3]

The value may be a converter list
(see {Converter Lists}[#class-CSV-label-Converter+Lists]):
  str = '1,3.14159'
  # Without converters
  array = CSV.parse_line(str)
  array # => ["1", "3.14159"]
  # With built-in converters
  array = CSV.parse_line(str, converters: [:integer, :float])
  array # => [1, 3.14159]

The value may be a \Proc custom converter:
(see {Custom Field Converters}[#class-CSV-label-Custom+Field+Converters]):
  str = ' foo  ,  bar  ,  baz  '
  # Without a converter
  array = CSV.parse_line(str)
  array # => [" foo  ", "  bar  ", "  baz  "]
  # With a custom converter
  array = CSV.parse_line(str, converters: proc {|field| field.strip })
  array # => ["foo", "bar", "baz"]

See also {Custom Field Converters}[#class-CSV-label-Custom+Field+Converters]

---

Raises an exception if the converter is not a converter name or a \Proc:
  str = 'foo,0'
  # Raises NoMethodError (undefined method `arity' for nil:NilClass)
  CSV.parse(str, converters: :foo)