Fix session usage

[fritzmg]

Fixes #63

The point of WidgetHelper::addFilesToSession was (presumably) to make Contao\Form::processFormData behave in the same way as with the regular file upload. i.e. if email sending is enabled, Contao will either attach the uploaded file to the email or append the absolute path to the image for easy access/download (when file storing is enabled).

However, this is currently not the case with the FineUploader. Any uploaded files only show up in the regular email content, with field name: relative/file/path. Uploaded files are not attached, nor is a direct link appended to the email by Contao.

This is because WidgetHelper::addFilesToSession uses Symfony's Session service to write the information to the session. However, Symfony's Session stores all session data always in "session bags" with unique namespaces (see Session Data Management), not directly to $_SESSION, in order to not interfere with other session data. Contao\Form::processFormData however uses $_SESSION['FILES'] directly, without Symfony's Session service - thus this never worked.

This PR fixes that by instead writing the session data directly to $_SESSION['FILES'] as expected from Contao\Form::processFormData.

Note: the Symfony Session is still added via Dependency Injection to the WidgetHelper, even though nothing in it uses it any more. Should I remove it?

[qzminski]

Sounds logical to me. Please remove the session dependency and I will merge this 😉

[qzminski]

Released as 1.3.7, thank you @fritzmg !

[tsarma]

Why is this fix got removed from version 3.3.3 to 3.4.*?

Related issues:
#93
#91
#75

[fritzmg]

Why is this fix got removed from version 3.3.3 to 3.4.*?

Likely due to its incompatibility with Contao 5.

[tsarma]

Oh ok. But unfortunate to remove it so early.