title: Typo3 Neos: Filefield in Custom Content Type
body: <p>I want to make a custom content type with the possibility to edit a download file. In my NodeTypes.yaml I have:</p>
  
  <pre><code>'Vendor.Prefix:MyContentType':
    superTypes: ['TYPO3.Neos:Content']
    ui:
      label: My Content Type
      icon: 'icon-file-text'
      inspector:
        groups:
          'props':
            label: Properties
    properties:
      'title':
        type: string
        defaultValue: 'Example Title'
        ui:
          label: 'Title'
          inlineEditable: TRUE
  </code></pre>
  
  <p>Now - how do I create a file upload field? I only found working examples for image fields:</p>
  
  <pre><code>'chapterImage':
    type: 'TYPO3\Media\Domain\Model\ImageVariant'
    ui:
      label: 'Chapter image'
      reloadIfChanged: TRUE
      inspector:
        group: 'document'
  </code></pre>
  
  <p>In the same folder, there are classes for file uploads, but this doesn't work:</p>
  
  <pre><code>'grundriss':
    type: 'TYPO3\Media\Domain\Model\Document'
    ui:
      label: 'Grundriss'
      editor: 'TYPO3.Neos/Inspector/Editors/FileUpload'
      inspector:
        group: 'props'
  </code></pre>
  
  <p>Neither with nor without the 'editor' line. It leads to the JavaScript error:</p>
  
  <pre><code>Uncaught TypeError: Cannot read property 'editor' of undefined 
  Uncaught Error: You cannot modify child views while in the inBuffer state 
  </code></pre>
  
  <p>And to an empty property inspector.</p>
  
  <p>Has anyone a tip for me?</p>