[TYPO3-Solr] How to index categories for simple records

[Michael Hübe]

Hi!

I am using TYPO3 6.x and categorize records with the core category api.
Now, I want to add them to the Solr index.

I have tried to use SOLR_MULTIVALUE and a user function to get the category titles, but it did not work.

Any ideas? May be an own indexer?

Thanks for help!