title: Angular 4 params with json stringify
body: <p>I have to stringify some parameter to put it in a http patch request my method is something like this</p>
  
  <pre><code>let param = JSON.stringify({
  code : this.code,
  name : this.name,
  fieldName: this.data
  });
  </code></pre>
  
  <p>In that case I have a param like this: </p>
  
  <blockquote>
    <p>code:3,name:'asdf',fieldName: 'col'</p>
  </blockquote>
  
  <p>But I want the value of fieldName ond not the word fieldName...
  Is there a method to expand or evaluate this parameter name?</p>