How to array_wrap an hash of hashes - arrays

Question

inv = {"C"=>{"CPS"=>{"CP"=>{"name"=>"a"}}}} is my object
I want
inv = {"C"=>{"CPS"=>{"CP"=>[{"name"=>"a"}]}}}
I tried
inv["C"]["CPS"].inject({}) do |result, (k, v)|
k = Array.wrap(v)
end
=> [{"name"=>"a"}]
but still inv={"C"=>{"CPS"=>{"CP"=>{"name"=>"a"}}}}
tries map also

Answer 1

Another option is to use tap
inv["C"]["CPS"].tap do |h|
h["CP"] = [h["CP"]] #or Array.wrap(h["CP"]) in rails
end
inv
#=> {"C"=>{"CPS"=>{"CP"=>[{"name"=>"a"}]}}}
tap will yield the current object so you can modify it in place.
Update
Inspired by #CarySwoveland's broader application you could use something like this as well.
class HashWrapper
attr_reader :original_hash
attr_accessor :target_keys
def initialize(h,*target_keys)
#original_hash = h
#target_keys = target_keys
end
def wrapped_hash
#wrapped_hash ||= {}
end
def wrap_me
original_hash.each do |k,v|
value = v.is_a?(Hash) ? HashWrapper.new(v,*target_keys).wrap_me : v
wrapped_hash[k] = wrap(k,value)
end
wrapped_hash
end
private
def wrap(k,v)
target_keys.include?(k) ? [v] : v
end
end
Then implementation is as follows
wrapper = HashWrapper.new(inv,"CP")
wrapper.wrap_me
#=> {"C"=>
{"CPS"=>
{"CP"=>
[
{"name"=>"a"}
]
}
}
}
new_wrapper = HashWrapper.new(inv,"CP","CPS")
new_wrapper.wrap_me
#=> {"C"=>
{"CPS"=>
[
{"CP"=>
[
{"name"=>"a"}
]
}
]
}
}
This assumes unique keys all the way through the hierarchy otherwise nested keys of the same name will be wrapped in the same fashion from the bottom up.
e.g.
inv = {"C"=>{"CPS"=>{"CP"=>{"name"=>"a"}},"CP" => "higher level"}}
HashWrapper.new(inv,"CP").wrap_me
#=> {"C"=>
{"CPS"=>
{"CP"=>
[
{"name"=>"a"}
]
},
"CP"=>
[
"higher level"
]
}
}

Answer 2

This should do it:
hash = {"C"=>{"CPS"=>{"CP"=>{"name"=>"a"}}}}
val = hash["C"]["CPS"]["CP"]
val_as_arr = [val] # can optionally call flatten here
hash["C"]["CPS"]["CP"] = val_as_arr
puts hash
# => {"C"=>{"CPS"=>{"CP"=> [{"name" => "a"}] }}}
basically
get the value
convert to array
set the value
There is no iteration required here i.e. map or reduce

Answer 3

I suggest you use recursion, in the form of a compact and easily readable method that has broader application than solutions that only work with your specific hash.
def wrap_it(h)
h.each { |k,v| h[k] = v.is_a?(Hash) ? wrap_it(v) : [v] }
h
end
h = { "C"=>{ "CPS"=>{ "CP"=>{ "name"=>"a" } } } }
wrap_it(h)
#=> {"C"=>{"CPS"=>{"CP"=>{"name"=>["a"]}}}}
h = { "C"=>{ "CPS"=>{ "CP"=>{ "CPPS"=> { "name"=>"cat" } } } } }
wrap_it(h)
#=> {"C"=>{"CPS"=>{"CP"=>{"CPPS"=>{"name"=>["cat"]}}}}}
h = { "C"=>{ "CPS"=>{ "CP"=>{ "CPPS"=> { "name"=>"cat" } },
"DP"=>{ "CPPPS"=>"dog" } } } }
wrap_it(h)
#=> {"C"=>{"CPS"=>{"CP"=>{"CPPS"=>{"name"=>["cat"]}}, "DP"=>{"CPPPS"=>["dog"]}}}}