Bug #4300: Merge keys not working as expected in psych yaml parser

• Status: Closed
• Assignee: tenderlovemaking (Aaron Patterson)
• Target version: -
• ruby -v: ruby 1.9.2p136 (2010-12-25 revision 30365) [x86_64-darwin10.6.0]

[wr0ngway (Matthew Conway)]

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Psych doesn't seem to support merge keys ( http://yaml.org/type/merge.html ) with alias/anchor the same way that syck does. I'm not sure if this is intentional or not, but its a pretty useful behavior so I'm filing a bug. Basically, while psych does allow one to use a merge key to pull a aliased mapping into another mapping, it does not allow one to add other items to that mapping. Very frequently I have a map that is mostly in common amongst a number of keys, with a subkey that differs, and this bug makes it impossible to achieve this behavior with psych.

For the yaml snippet below:

foo: &foo
hello: world
bar:
<< : *foo
baz: boo

syck produces: {"foo"=>{"hello"=>"world"}, "bar"=>{"hello"=>"world", "baz"=>"boo"}}

psych produces: {"foo"=>{"hello"=>"world"}, "bar"=>{"hello"=>"world"}}

Note that in the yaml 1.1 spec ( http://yaml.org/spec/1.1/#id902561 ) it says "Note that an alias node must not specify any properties or content, as these were already specified at the first occurrence of the node.", however I think this should only apply when doing something like "bar: *foo". When using a merge key, you are creating a new node (which you don't add to), but merging it into a different mapping node - which you should be able to add to.

For reference, also submitted at https://github.com/tenderlove/psych/issues#issue/8/comment/693341
=end

[naruse (Yui NARUSE)]

• Category changed from core to ext
• Status changed from Open to Assigned
• Assignee set to tenderlovemaking (Aaron Patterson)

=begin

=end

• Status changed from Assigned to Closed
• % Done changed from 0 to 100

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This issue was solved with changeset r30629.
Matthew, thank you for reporting this issue.
Your contribution to Ruby is greatly appreciated.
May Ruby be with you.

---

• ext/psych/lib/psych/visitors/to_ruby.rb: merge keys are actually
  part of YAML 1.1, so they should be supported. Remove warning and
  merge keys to parent. [ruby-core:34679]
• test/psych/test_merge_keys.rb: test for merge keys
  =end

[wr0ngway (Matthew Conway)]

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Thanks!
Do I have to do anything special to get this backported to 1.9.2?

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[tenderlovemaking (Aaron Patterson)]

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On Wed, Feb 02, 2011 at 10:05:55AM +0900, Matthew Conway wrote:

Issue #4300 has been updated by Matthew Conway.

Thanks!
Do I have to do anything special to get this backported to 1.9.2?

I don't think so. I've filed a ticket to backport the merge key fixes
here:

http://redmine.ruby-lang.org/issues/show/4357

--
Aaron Patterson
http://tenderlovemaking.com/

Attachment: (unnamed)
=end

[firedev (Nick O)]

Sorry but this isn't fixed as of Ruby 1.9.3p374 (2013-01-15 revision 38858)

https://github.com/tenderlove/psych/issues/8#issuecomment-12541499

[luislavena (Luis Lavena)]

• Description updated (diff)

firedev (Nick O) wrote:

Sorry but this isn't fixed as of Ruby 1.9.3p374 (2013-01-15 revision 38858)

https://github.com/tenderlove/psych/issues/8#issuecomment-12541499

This is not backported to 1.9.3, this is fixed in trunk.

Please submit a backport request indicating the original issue, the revisions that needs to be backported and assign to usa.

Thank you.