title: Submitting a form with image Flutter - type '_File' is not a subtype of type 'String'
body: <p>This is my payload:</p>
  
  <pre><code>final Map&lt;String, dynamic&gt; registration = {
          'company_name': _companyName,
          'team_name': _teamName,
          'image': _image
        };
  </code></pre>
  
  <p><code>company_name</code> and <code>team_name</code> are string as expected. However, <code>_image</code> is defined like below:</p>
  
  <pre><code>File _image;
  </code></pre>
  
  <p>So when I do the post request I am getting the below error on terminal:</p>
  
  <blockquote>
    <p>type '_File' is not a subtype of type 'String' in type cast</p>
  </blockquote>
  
  <p>I know this is happening because I defined <code>registration</code> as <code>&lt;String, dynamic&gt;</code>. How to fix this?</p>