Monkey Patch the Hash class to add the following methods -
A "#symbolize_keys" method that transforms all keys in any arbitrarily complex nested hash from strings to symbols An "#extract_nested_keys" method for extracting all keys from an arbitrarily complex nested hash A "#fetch_nested(arg)" method for finding the value of a key from an arbitrarily complex nested hash
The arbitrarily complex nested hash:
{ 'a' => { 'b' => 'Hello', 'c' => { 'd' => { 'e' => 'Nesting' }, 'f' => { 'g' => [1, 2, 3] }, 'h' => 'Very silly hash' }, 'i' => 15 } }
The result of #symbolize_keys should be this:
{:a=>{:b=>"Hello", :c=>{:d=>{:e=>"Nesting"}, :f=>{:g=>[1, 2, 3]}, :h=>"Very silly hash"}, :i=>15}}
The result of #extract_nested_keys should be this:
["a", "b", "c", "d", "e", "f", "g", "h", "i"]
The result of passing in any key that exists in the hash to the #fetch_nested method should return that value, i.e. passing it 'e' will return 'Nesting', pass it a key that doesn't exist in any depth of the nested hash returns nil.
Answer 1:
def symbolize_keys(hash)
hash.inject({}){|result, (key, value)|
new_key = case key
when String then key.to_sym
else key
end
new_value = case value
when Hash then symbolize_keys(value)
else value
end
result[new_key] = new_value
result
}
end
Answer 2:
class Hash
def find_all_values_for(key)
result = []
result << self[key]
self.values.each do |hash_value|
values = [hash_value] unless hash_value.is_a? Array
values.each do |value|
result += value.find_all_values_for(key) if value.is_a? Hash
end
end
result.compact
end
end
To do:
- Finish testing with RSpec
- Research and understand how to pass keys into nested hashes to extract the corresponding values
- Fully test the results
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