I m building an xml document from a hash. The xml attributes need to be in order. How can this be accomplished?
hash.to_xml
Ruby 1.8 s hash aren t in insertion order. With ruby 1.9, they will be.
However rails offers an alternative to that, the class OrderedHash.
my_hash = ActiveSupport::OrderedHash.new
my_hash[:key] = value
my_hash[:second_key] = second value
This hash is in fact an array of that format :
[[:key, value ], [:second_key, second value ]]
The entries remains in the order you inserted them.
And you can access them like with any other hash.
h = Hash[:x,123,:a,553,:d,949,:e,5321]
=> {:e=>5321, :x=>123, :a=>553, :d=>949}
h.sort { |x,y| x[0].to_s <=> y[0].to_s }
=> [[:a, 553], [:d, 949], [:e, 5321], [:x, 123]]
The usual ways of sorting a hash is by key or value. Have a look here:
More complex sorts can be accomplised however by utilizing the spaceship operator
What order did you want them to be in? You shouldn t expect them to be in insertion order. From the docs for Hash:
The order in which you traverse a hash by either key or value may seem arbitrary, and will generally not be in the insertion order.
If you need them to be in a specific order you can determine just from the keys/values (e.g. order the attribute names alphabetically), you ll need to apply that ordering explicitly.
This piece of code I ve just made for i18n-js might help you out as it convert Hash to ActiveSupport::OrderedHash if needed then sort it s key by natural order.
http://seb.box.re/2010/1/15/deep-hash-ordering-with-ruby-1-8
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I m building an xml document from a hash. The xml attributes need to be in order. How can this be accomplished? hash.to_xml
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