[ACCEPTED]-Is it possible to specify formatting options for to_yaml in ruby?-yaml

Accepted answer
Score: 11

About the hash options: see http://yaml4r.sourceforge.net/doc/page/examples.htm

Ex. 24: Using 16 to_yaml with an options Hash

puts [[ 'Crispin', 'Glover' ]].to_yaml( :Indent => 4, :UseHeader => true, :UseVersion => true )
# prints:
#   --- %YAML:1.0
#   -
#       - Crispin
#       - Glover

Ex. 25: Available symbols 15 for an options Hash

Indent: The default indentation 14 to use when emitting (defaults to 2)
Separator: The 13 default separator to use between documents 12 (defaults to '---')
SortKeys: Sort Hash keys when emitting? (defaults 11 to false)
UseHeader: Display the YAML header when emitting? (defaults 10 to false)
UseVersion: Display the YAML version when emitting? (defaults 9 to false)
AnchorFormat: A formatting string for anchor 8 IDs when emitting (defaults to 'id%03d')
ExplicitTypes: Use 7 explicit types when emitting? (defaults 6 to false)
BestWidth: The character width to use when 5 folding text (defaults to 80)
UseFold: Force folding 4 of text when emitting? (defaults to false)
UseBlock: Force 3 all text to be literal when emitting? (defaults 2 to false)
Encoding: Unicode format to encode with (defaults 1 to :Utf8; requires Iconv)

Score: 8

Starting from Ruby 1.9 psych is used as a default 2 YAML engine. It supports some attributes: http://ruby-doc.org/stdlib-2.1.0/libdoc/psych/rdoc/Psych/Handler/DumperOptions.html

So 1 for me it works:

irb(main):001:0> require 'yaml'
=> true
irb(main):002:0> puts [{'a'=> 'b', 'c'=> 'd'}, {'e'=> 'f', 'g'=>'h'}].to_yaml(:indentation => 4)
-   a: b
    c: d
-   e: f
    g: h
Score: 6

This ugly hack seems to do the trick...

class Array
  def to_yaml_style

Browsing 3 through ruby's source, I can't find any 2 options I could pass to achieve the same. Default 1 options are described in the lib/yaml/constants.rb.

Score: 1

Just another hack to specify the output 3 style, but this one allows to customize 2 it per specific object, instead of globally 1 (e.g. for all arrays).


Simple example:

class Movie
  attr_accessor :genres, :actors

  # method called by psych to render YAML
  def encode_with(coder)
    # render array inline (flow style)
    coder['genres'] = StyledYAML.inline(genres) if genres
    # render in default style (block)
    coder['actors'] = actors if actors
Score: 0

The latest versions of Ruby use the Psych 4 module for YAML parsing. There aren't many 3 options that you can pass but you can change 2 indention and line width. Check the latest 1 Psych documentation for more details.

Score: 0

Use Psych directly.

Indentation has no effect: my_yaml.to_yaml(:indentation => 2)

Indentation 1 works: Psych.dump(my_yaml, :indentation => 8)

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