title: map[string]interface{} to struct with json tags
body: <p>I need to convert a <code>map[string]interface{}</code> whose keys are json tag names to <code>struct</code> </p>
  
  <pre><code>type MyStruct struct {
      Id           string `json:"id"`
      Name         string `json:"name"`
      UserId       string `json:"user_id"`
      CreatedAt    int64  `json:"created_at"`
  }
  </code></pre>
  
  <p>The <code>map[string]interface{}</code> has keys <code>id</code>, <code>name</code>, <code>user_id</code>, <code>created_at</code>. I need to convert this into <code>struct</code>.</p>