title: Default value golang struct using `encoding/json` ?
body: <p>How to set default value for <code>Encoding</code> as  "base64"?</p>
  
  <pre><code>type FileData struct {
      UID string `json:"uid"`                 
      Size int `json:"size"`
      Content string `json:content`
      Encoding string `json:encoding` 
      User string `json:"user"`
  }
  </code></pre>
  
  <p>I tried </p>
  
  <pre><code>Encoding string `json:encoding`= "base64" // Not working
  </code></pre>