CODEWITHSUNDEEP
ruby-on-railsrubyyamlto-yaml
Tom Prats
Tom Prats

Reputation: 7921

How do I parse a field in a YAML file into three more fields in the same file?

I have a YAML file containing:

cat:
  name: Cat
  description: catlike reflexes
dog:
  name: Dog
  description: doggy breath

I want to parse it and break the description into key1 and key2 like so:

cat:
  name: Cat
  description: catlike reflexes
  info:
    key1: catlike
    key2: reflexes
dog:
  name: Dog
  description: doggy breath
  info:
    key1: doggy
    key2: breath

But, for some reason, I cannot do this correctly. What I've tried so far are variations of the code below, which I think I'm overcomplicating:

# to get the original file's data
some_data = YAML.load(File.open("#{Rails.root}/config/some_data.yml"))

new_data = some_data.collect do |old_animal|
  animal = old_animal.second

  if animal && animal["description"]
    new_blocks = Hash.new
    blocks = animal["description"].split(" ")
    new_blocks["key1"] = blocks.first
    new_blocks["key2"] = blocks.second
    animal["info"] = new_blocks
  end
  old_animal.second = animal
  old_animal
end

# to write over the original file
File.write("#{Rails.root}/config/some_data.yml", new_data.to_yaml)

Upvotes: 1

Views: 724

Answers (1)

the Tin Man
the Tin Man

Reputation: 160571

You don't say whether or not you can have multiple words in the description, but it's kind of common-sense you would, so I'd do something like this:

require 'yaml'

data = YAML.load(<<EOT)
cat:
  name: Cat
  description: catlike reflexes rules
dog:
  name: Dog
  description: doggy breath
EOT
data # => {"cat"=>{"name"=>"Cat", "description"=>"catlike reflexes rules"}, "dog"=>{"name"=>"Dog", "description"=>"doggy breath"}}

At this point the data from the YAML file is loaded into a hash. Iterate over each hash key/value pair:

data.each do |(k, v)|
  descriptions = v['description'].split
  keys = descriptions.each_with_object([]) { |o, m| m << "key#{(m.size + 1)}" }
  hash = keys.each_with_object({}) { |o, m| m[o] = descriptions.shift }
  data[k]['info'] = hash
end

This is what we got back:

data # => {"cat"=>{"name"=>"Cat", "description"=>"catlike reflexes rules", "info"=>{"key1"=>"catlike", "key2"=>"reflexes", "key3"=>"rules"}}, "dog"=>{"name"=>"Dog", "description"=>"doggy breath", "info"=>{"key1"=>"doggy", "key2"=>"breath"}}}

And what it'd look like if it was output:

puts data.to_yaml
# >> ---
# >> cat:
# >>   name: Cat
# >>   description: catlike reflexes rules
# >>   info:
# >>     key1: catlike
# >>     key2: reflexes
# >>     key3: rules
# >> dog:
# >>   name: Dog
# >>   description: doggy breath
# >>   info:
# >>     key1: doggy
# >>     key2: breath

each_with_object is similar to inject but a little cleaner to use because it doesn't require we return the object we're accumulating into.

Upvotes: 1

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