title: Angular 5 'Content-Type': 'multipart/form-data' gets reset to 'application/json'
body: <p>Hi I am having trouble trying to get my httpClient patch request to send FormData with content type 'multipart/form-data'.</p>
  
  <p>I have specified the headers as shown:</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>  private httpOptions = {
      headers: new HttpHeaders({
        'Content-Type': 'multipart/form-data', 'Cache-Control': 'no-cache', 'Pragma': 'no-cache'
      })
    };</code></pre>
  </div>
  </div>
  </p>
  
  <p>And I do the following to save to the nodejs server:</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>const formData: FormData = new FormData();
  formData.append('materialFile', 'something');
  return this.httpClient.patch&lt;any&gt;(this.apiUrl  + loan.id, formData, this.httpOptions);</code></pre>
  </div>
  </div>
  </p>
  
  <p>On my Nodejs/Express server I do the following:</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>const Multer  = require('multer');
  
  router.patch('/:id', Multer().fields([{ name: "materialFile", maxCount: 1 }]), (req, res, next) =&gt; {
    console.log(req.files['materialFile']);
  });</code></pre>
  </div>
  </div>
  </p>
  
  <p>When I inspect the request headers on the browser I see that the content-type is application/json.</p>
  
  <p>Anybody knows why?</p>