Is there a way to tell Psych in ruby to using inline mode?

Question

environment: ruby1.9.3 , psych(any version) ex:

o = { 'hash' => { 'name' => 'Steve', 'foo' => 'bar' } } 
 => {"hash"=>{"name"=>"Steve", "foo"=>"bar"}} 

#is there a inline option?
puts Psych.dump(o,{:inline =>true})

real result:

---
hash:
  name: Steve
  foo: bar

expect output:

--- 
hash: { name: Steve, foo: bar }

Answer 1

Psych supports this, although it isn't at all straightforward.

I've started researching this in my own question on how to dump strings using literal style.

I ended up devising a complete solution for setting various styles for specific objects, including inlining hashes and arrays.

With my script, a solution to your problem would be:

o = { 'hash' => StyledYAML.inline('name' => 'Steve', 'foo' => 'bar') }
StyledYAML.dump o, $stdout

Answer 2

The representable gem provides this in a convenient OOP style.

Considering you have a model User:

user.name => "Andrew"
user.age => "over 18"

You'd now define a representer module to render/parse User instances.

require 'representable/yaml'

module UserRepresenter
  include Representable::YAML

  collection :hash, :style => :flow

  def hash
    [name, age]
  end
end

After defining the YAML document you simply extend the user instance and render it.

user.extend(UserRepresenter).to_yaml
#=> ---
hash: [Andrew, over 18]

Hope that helps, Andrew!