From: Tamara Temple <tamouse.lists@...>
Date: 2013-07-21T15:46:15+09:00
Subject: Re: ActiveSupport undercore behaviour


On Jul 20, 2013, at 2:51 PM, Serguei Cambour <lists@ruby-forum.com> wrote:

> I tried to use ActiveSupport 'underscore' method to convert some
> non-conventional to RoR data to be able to update later some attributes
> as follows:
> 
> TECHS = {"platform"=>[
>                {"AssignedName"=>"P1", "ExportPrice"=>"USD", "Id"=>"1",
> "Delivery"=>"Y",
>                    "RegisteredMembers"=>[
>                      {"Name"=>"Admin", "Id"=>"3",
>                          "AvailablePosts"=>[
>                              {"Seat"=>"2", "Colour"=>18, },
>                              {"Seat"=>"3", "Colour"=>19, },
>                              {"Seat"=>"4", "Colour"=>181, },
>                              {"Seat"=>"5", "Colour"=>183, }
>                          ]
>                      }
>                     ]
>                }
>              ]
>            }
> 
> TECHS.each_value do |value|
>  arr = value.map {|k,v| [ActiveSupport::Inflector.underscore(k.to_s),
> v]}
>  puts "ARR: #{arr.inspect}"
> end
> 
> The result is strange even if the values look underscored:
> 
> ARR: [["{\"assigned_name\"=>\"p1\", \"export_price\"=>\"usd\",
> \"id\"=>\"1\", \"delivery\"=>\"y\",
> \"registered_members\"=>[{\"name\"=>\"admin\", \"id\"=>\"3\",
> \"available_posts\"=>[{\"seat\"=>\"2\", \"colour\"=>18},
> {\"seat\"=>\"3\", \"colour\"=>19}, {\"seat\"=>\"4\", \"colour\"=>181},
> {\"seat\"=>\"5\", \"colour\"=>183}]}]}", nil]]
> 
> Why are there some extra quotes and nil in the very end ? Thkx
> 
> -- 
> Posted via http://www.ruby-forum.com/.
> 

Not 100% sure what you're seeing as extra quotes, but the nil is what you get from declaring two passed in values from the map method -- it only passes in the current value of the array that your original TECH['platform'] is pointing at, so k is current value, v is always nil.

2.0.0-p247 :008 > [1, 2, 3, 4].map{|k,v| [k,v]}
 => [[1, nil], [2, nil], [3, nil], [4, nil]] 

Even if your array elements are hashes, there's still only one value passed in from map:
2.0.0-p247 :009 > [{a: 1, b: 2, c: 3}, {aa: 11, bb: 22, cc: 33}].map{|k,v| [k,v]}
 => [[{:a=>1, :b=>2, :c=>3}, nil], [{:aa=>11, :bb=>22, :cc=>33}, nil]]