如何从 ruby 中的哈希数组更改 hash 键？

Question

Given:

data = [
  {"votable_id"=>1150, "user_ids"=>"1,2,3,4,5,6,"},
  {"votable_id"=>1151, "user_ids"=>"55,66,34,23,56,7,8"}
]

This is the expected result. Array should have first 5 elements.

data = [
  {"votable_id"=>1150, "user_ids"=>["1","2","3","4","5"]},
  {"votable_id"=>1151, "user_ids"=>["55","66","34","23","56","7",8"]}
]

This is what I tried:

data.map{|x| x['user_ids'] = x['user_ids'].split(',').first(5)}

Any other optimized solution?

Answer 1

You can also use .map and .tap like this

data.map do |h|
 h.tap { |m_h| m_h["user_ids"]= m_h["user_ids"].split(',').first(5)}
end

Answer 2

data = [
    {"votable_id"=>1150, "user_ids"=>"1,2,3,4,5,6,"},
    {"votable_id"=>1151, "user_ids"=>"55,66,34,23,56,7,8"}
]

Code

h=data.map do |h|
  h["user_ids"]=[h["user_ids"].split(',').first(5)].flatten
  h
end

p h

Output

[{"votable_id"=>1150, "user_ids"=>["1", "2", "3", "4", "5"]}, {"votable_id"=>1151, "user_ids"=>["55", "66", "34", "23", "56"]}]

Answer 3

data.map { |h| h.merge("user_ids"=>h["user_ids"].split(',').first(5)) }
  #=> [{"votable_id"=>1150, "user_ids"=>["1", "2", "3", "4", "5"]},
  #    {"votable_id"=>1151, "user_ids"=>["55", "66", "34", "23", "56"]}] 

See Hash#merge . This leaves data unchanged. To modify (or mutate ) data use Hash#merge! (aka update ). h.merge(k=>v) is a shortcut for h.merge({ k=>v }) .