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module Hashie
module Extensions
# Searches a deeply nested datastructure for a key path, and returns the associated value.
#
# options = { user: { location: { address: '123 Street' } } }
# options.deep_fetch :user, :location, :address #=> '123 Street'
#
# If a block is provided its value will be returned if the key does not exist.
#
# options.deep_fetch(:user, :non_existent_key) { 'a value' } #=> 'a value'
#
# This is particularly useful for fetching values from deeply nested api responses
# or params hashes.
module DeepFetch
class UndefinedPathError < StandardError; end
def deep_fetch(*args, &block)
args.reduce(self) do |obj, arg|
begin
arg = Integer(arg) if obj.is_a? Array
obj.fetch(arg)
rescue ArgumentError, IndexError, NoMethodError => e
break yield(arg) if block
raise UndefinedPathError,
"Could not fetch path (#{args.join(' > ')}) at #{arg}", e.backtrace
end
end
end
end
end
end
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