title: Regular expression to retain part of the string
body: <p>I have a string of following kind</p>
  
  <pre><code>{"pid":{"source":"Doc","name":"pid","value":"8180"},
  "cid":{"source":"Doc","name":"cid","value":null},
  "fid":{"source":"Doc","name":"fid","value":"ME453REN0004"}}
  </code></pre>
  
  <p>I need to get the following string</p>
  
  <pre><code>  {"pid":"8180",
     "cid":null,
     "fid":"ME453REN0004"}
  </code></pre>
  
  <p>How can use the regular expression for this?</p>