How to get “x[y][z]” out of a hash ?
This made life with our form helpers a lot easier, since they take normal or nested keys <-> name of the input and prefilled value through params.
Any alternative is appreciated, since its pretty complex/hacky, the name is weird too …
(a simple to_query.split(‘=’)).inject… can work too, but would stringify all values and keys)
Usage
{'x'=>{'y'=>{'z'=>1}}}.value_from_nested_key('x[y][z]') == 1
Code
class Hash
# {'x'=>{'y'=>{'z'=>1}}.value_from_nested_key('x[y][z]') => 1
def value_from_nested_key(key)
if key.to_s.include?('[')
match, first, nesting = key.to_s.match(/(.+?)\[(.*)\]/).to_a
value = self[first]
nesting.split('][').each do |part|
return nil unless value.is_a?(Hash)
value = value[part]
end
value
else
self[key]
end
end
end
Michael Grosser, the Blog 
I tried something like…
def keys_array @keys_array = [] end def deep_print_keys(hash_or_array) if hash_or_array.is_a? Hash hash_or_array.each_pair do |k,v| @keys_array << k if v.is_a? Hash deep_print_keys(v) else v.is_a? Array v.each{|element| deep_print_keys(element) } end end end end keys_array deep_print_keys(xml_hash) @keys_array.uniq.sort.each{|key| puts key}that will give me all keys of a given hash, and does nothing for an array?
what i am trying to do is getting the nested key ‘x[y][z]’ from a hash like {‘x’=>{‘y’=>{‘z’=>3}}}