蛻變散列結構

Question

我有一個大JSON對象本身（但X100 +）：

[ 
    { 
     "category": "category1", 
     "text": "some text" 
    }, 
    { 
     "category": "category2", 
     "text": "some more text" 
    }, 
    { 
     "category": "category1", 
     "text": "even more text" 
    } 
] 

如何將蛻變到這一點：

{ 
    "category1": [ 
     { 
      "text": "some text" 
     }, 
     { 
      "text": "even more text" 
     } 
    ], 
    "category2": { 
     "text": "even more text" 
    } 
} 

在正確的方向的任何幫助，將不勝感激。

Answer 1

首先，您需要將您的JSON字符串轉換爲Ruby對象。

require "json" 
json = %{ 
[ 
    { 
     "category": "category1", 
     "text": "some text" 
    }, 
    { 
     "category": "category2", 
     "text": "some more text" 
    }, 
    { 
     "category": "category1", 
     "text": "even more text" 
    } 
] 
} 
ary = JSON.parse(json) 

現在，我們已經在Ruby的形式哈希值的數組，我們可以操縱它

h = ary.group_by {|i| i["category"]} 
#=> {"category1"=>[{"category"=>"category1", "text"=>"some text"}, {"category"=>"category1", "text"=>"even more text"}], "category2"=>[{"category"=>"category2", "text"=>"some more text"}]} 

h = h.map {|k,v| {k => v.map {|t| {"text" => t["text"]}}}} 
#=> [{"category1"=>[{"text"=>"some text"}, {"text"=>"even more text"}]}, {"category2"=>[{"text"=>"some more text"}]}] 

h = h.reduce(&:merge) 
#=> {"category1"=>[{"text"=>"some text"}, {"text"=>"even more text"}], "category2"=>[{"text"=>"some more text"}]} 

打印JSON在美麗的形式，檢查結果

puts JSON.pretty_generate(h) 

輸出：

{ 
    "category1": [ 
    { 
     "text": "some text" 
    }, 
    { 
     "text": "even more text" 
    } 
    ], 
    "category2": [ 
    { 
     "text": "some more text" 
    } 
    ] 
} 

Answer 2

Enumerable#each_with_object可能會有所幫助。類似於

json.each_with_object({}) do |h, acc| 
    acc[h[:category]] ||= [] 
    acc[h[:category]] << {text: h[:text]} 
end # {"category1"=>[{:text=>"some text"}, {:text=>"even more text"}], "category2"=>[{:text=>"some more text"}]} 

其中json是您的原始數組。

Answer 3

def transmute(arr) 
    out = Hash.new { |hash, key| hash[key] = [] } 
    arr.inject(out) do |h, e| 
    key = e[:category].to_sym 
    entry = {text: e[:text]}   
    h[key] << entry 
    h 
    end 
end 

工作代碼/規格段： http://rubysandbox.com/#/snippet/56784c32793916000c000000

Answer 4

假設得到的結果"category2": [{"text": "some more text"}]：

array.map(&:dup).group_by{|h| h.delete(:category)}