title: Sum of json array
body: <p>I have json type field, something like this</p>
  
  <p><strong>data</strong></p>
  
  <pre><code>{"age": 44, "name": "Jun"}
  
  {"age": 19, "name": "Pablo", "attempts": [11, 33, 20]}
  
  {"age": 33, "name": "Maria", "attempts": [77, 10]}
  </code></pre>
  
  <p>Here some json data have "attempts" array, some not. When json have this array, I need get sum of array elements in different field, need result like</p>
  
  <p><strong>data , sum_of_array</strong></p>
  
  <pre><code>{"age": 44, "name": "Jun"} , (nothing here)
  
  {"age": 19, "name": "Pablo", "attempts": [11, 33, 20]} , 64
  
  {"age": 33, "name": "Maria", "attempts": [77, 10]} , 87
  </code></pre>