TYPO3 Core

The ext:form setup contains some predefined mime types for the elements "FileUpload" and "ImageUpload"

• https://github.com/TYPO3/TYPO3.CMS/blob/master/typo3/sysext/form/Configuration/Yaml/BaseSetup.yaml#L254
• https://github.com/TYPO3/TYPO3.CMS/blob/master/typo3/sysext/form/Configuration/Yaml/BaseSetup.yaml#L260

Such predefined values are used as starting values while the form element is factorized:

• https://github.com/TYPO3/TYPO3.CMS/blob/master/typo3/sysext/form/Classes/Domain/Factory/ArrayFormFactory.php#L104
• https://github.com/TYPO3/TYPO3.CMS/blob/master/typo3/sysext/form/Classes/Domain/Model/FormElements/AbstractSection.php#L138

later on, the values from the form definition will be overlayed (https://github.com/TYPO3/TYPO3.CMS/blob/master/typo3/sysext/form/Classes/Domain/Model/FormElements/AbstractFormElement.php#L148):

• https://github.com/TYPO3/TYPO3.CMS/blob/master/typo3/sysext/form/Classes/Domain/Factory/ArrayFormFactory.php#L119

A form definition like this

type: Form
identifier: test-1
label: test
prototypeName: standard
renderables:
  -
    type: Page
    identifier: page-1
    label: Step
    renderables:
      -
        type: FileUpload
        identifier: fileupload-1
        label: 'File upload'
        properties:
          saveToFileMount: '1:/user_upload/'
          allowedMimeTypes:
            - application/pdf

ends up in a form element like this

        type: FileUpload
        identifier: fileupload-1
        label: 'File upload'
        properties:
          saveToFileMount: '1:/user_upload/'
          allowedMimeTypes:
            - application/msword
            - application/vnd.openxmlformats-officedocument.wordprocessingml.document
            - application/vnd.oasis.opendocument.text
            - application/pdf

We need to remove the predefined mime types from the ext:form setup-