From checking the template Resources/Private/Partials/Module/Export.html
I had the idea, to add it to the template, but wasn't sure which ID.
After some debugging through the extension I realized, that my custom field can easy be added to the ul.extended_export_field
by the mentioned template, because it was already in the {page.fields}
array. The condition for {field.advancedFieldType}
prevented rendering the custom field, because it's type isn't in the advanced and basic fields.
You have therefore 2 solutions to fix that:
change Classes/Domain/Model/Field.php
within your extension
and extend the $advancedFieldTypes
or $basicFieldTypes
array
change the template Resources/Private/Partials/Module/Export.html
by adding a condition for your custom field type and render it into the list like <li id="{field.uid}">{field.title} <span class="info">(<f:translate key="FormField" />)</span></li>
What I still not know is how to manipulate the output within the export.
Update:
Output can be modified within
Resources/Private/Templates/Module/ExportCsv.html