How can I get context generated by my custom context processors to be available in the haystack index template?
(I mean: the template file that haystack reads when you do ./manage.py rebuild_index)
I can load my custom filters with an explicit {% load %} template tag, but I can't see how to get the custom context loaded. When I try to use it, it behaves as if the custom context is not defined.
I need it because the searchable (string) representation of some of the fields of the objects requires a function to generate it (the field is effectively an enum, but the user wants to search for the full text string of the value in that field).
OK, I was confused by your use of "index template" - as I understand it, you're taking about the template used to construct the search document indexed by Haystack.
As you note, there is no request involved when that is rendered, so you can't use a RequestContext. That should really be a clue that context processors are not the right solution: you should be using template tags and filters instead.