The following code
require 'yaml'
class MyObject
def initialize(value)
@value = value
end
def to_yaml()
@value + @value
end
end
puts [MyObject.new("a"), MyObject.new("b")]
Generated the following output on Ruby 2.1.3p242:
---
- !ruby/object:MyObject
value: a
- !ruby/object:MyObject
value: b
Where I expected it to be
---
- aa
- bb
As if I called to_yaml
on every object inside the Array:
puts [MyObject.new("a").to_yaml, MyObject.new("b").to_yaml]
What am I doing wrong?
I'm leaving the previous answer as well, since it might come in handy for someone, but here's the better solution.
I've actually over-simplified the original problem. I'm trying to get my custom object to be rendered as a YAML sequence [1, 2, 3, ...]
. The previous answer could work for objects that are being rendered as Strings.
Here's the working version:
require 'yaml'
class MyObject
def initialize(value)
@value = value
end
def encode_with coder
coder.tag = nil
coder.seq = [@value, @value]
end
end
puts [MyObject.new("a"), MyObject.new("b")].to_yaml
Some references:
http://blog.mustmodify.com/pages/psych-ruby-1-9-yaml
http://ruby-doc.org/stdlib-1.9.3/libdoc/psych/rdoc/Psych/Coder.html
I'm replacing the visit_Array
method of the Psych::Visitors::YAMLTree
class MyVisitor < Psych::Visitors::YAMLTree
def visit_Array o
super o.map { |i| i.respond_to?(:to_yaml) ? i.to_yaml : i }
end
end
Then, I'm dumping the YAML this way:
a = [MyObject.new("a"), MyObject.new("b")]
visitor = MyVisitor.create
visitor << a
puts visitor.tree.yaml
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