I have my own TYPO3 plugin that displays records. Now I want to add a link to a second page to each record.
The second page should be a powermail form. Now I want that the link to the second Mail contains a parameter that should prefill a input field in the powermail form.
Is that possible? And if so how?
Yes it is possible. See documentation of powermail: https://docs.typo3.org/typo3cms/extensions/powermail/ForAdministrators/BestPractice/PrefillField/Index.html
The standard way
Prefilling (input, textarea, hidden) or preselecting (select, check, radio) of fields will be done by the PrefillFieldViewHelper. It listen to the following methods and parameters (in this ordering):
Fill with TypoScript cObject like
Fill with simple TypoScript like
Fill with your own PHP with a Signal. Look at In2codePowermailViewHelpersMiscPrefillFieldViewHelper::render()