Ruby iterating over hash of hash

Question

I have the following array and am struggling to format it for my needs.

consolidated = [
  {:name=>"Bob",   :details=>{"work"=>"Carpenter", "age"=>"26", "Experience"=>"6"} },
  {:name=>"Colin", :details=>{"work"=>"painting",  "age"=>"20", "Experience"=>"4"} }
]

I am trying to format it as below:

Bob    work         Carpenter
       age          26
       Experience   6

Colin  work         painting
       age          20
       Experience   4

I tried the following:

require 'csv'
CSV.open("output.csv", "wb") do |csv|
  csv << ["name", "nature", "details"]
  consolidated.each do |val|
    csv << [val[:name], val[:details]]
  end
end
  #=> [{:name=>"Bob",   :details=>{"work"=>"Carpenter", "age"=>"26", "Experience"=>"6"}},
  #    {:name=>"Colin", :details=>{"work"=>"painting", "age"=>"20", "Experience"=>"4"}}]

but it prints the following

name      nature                                                  details

Bob      "work"=>"Carpenter", "age"=>"26", "Experience"=>"6"

Colin    "work"=>"painting", "age"=>"20", "Experience"=>"4"

I'm not exactly sure how to iterate hash of hash from the 1st loop only to get the expected format.

Thanks.

Answer 1

Here's something to get you started:

require 'csv'
data = [
  {:name => "Bob", :details=>{"work"=>"Carpenter", "age"=>"26", "Experience"=>"6"}},
  {:name => "Colin", :details=>{"work"=>"painting", "age"=>"20", "Experience"=>"4"}}
]

str = CSV.generate do |csv|
  data.each do |datum|
    datum[:details].each do |detail_key, detail_value|
      csv << [datum[:name], detail_key, detail_value]
    end
  end
end

puts str
# >> Bob,work,Carpenter
# >> Bob,age,26
# >> Bob,Experience,6
# >> Colin,work,painting
# >> Colin,age,20
# >> Colin,Experience,4

Simply iterate all details and emit a new row for each key-value pair there, adding a name of a person.

This will get you almost what you need. Missing only blank rows between sections and person's name is duplicated on each line. It'll be your homework to find out how to add those improvements.

Answer 2

I don't know about CSV generation (so, assuming it works as you have written), you can iterate on your object this way:

consolidated = [{:name => "Bob", :details=>{"work"=>"Carpenter", "age"=>"26", "Experience"=>"6"}}, {:name => "Colin", :details=> {"work"=>"painting", "age"=>"20", "Experience"=>"4"}}]


CSV.open("output.csv", "wb") do |csv|
  csv << ["name", "nature", "details"]

  consolidated.each do |val|
    details = val[:details]
    nature_1 = details.keys.first
    detail_1 = details.delete(nature_1)
    csv << [val[:name], nature_1, detail_1]

    details.each do |k, v|
      csv << [nil, k, v]
    end
  end
end

Note: This will corrupt your original data array consolidated . So, if you want to preserve it, dup it first. Or modify the logic to not delete the first key-value from val[:details] .

Answer 3

You need to iterate the embedded hash by each_pair iterator. Something like this:

data = {:name => "Bob", :details=>{"work"=>"Carpenter", "age"=>"26", "Experience"=>"6"}}

CSV.open("output.csv", "wb") do |csv|

  csv << ["name", "nature", "details"]

  data.each do |val|

    csv << [ val[:name], val[:details]['work'] ]

    data[:details].each_pair do |key, value]

      # here we have to drop the first pair because i've used it earlier 
      next if key == 'work'

      csv << [ "", key, value ]

    end

  end

end