Using payloads for expanded query terms

[Manuel Le Normand <ma...@gmail.com>]

Hello,
I'm trying to handle a situation with taxonomy search - that is for each
taxonomy I have a list of words with their boosts. These taxonomies are
updated frequently so I retrieve these scored lists at query time from an
external service.

My expectation would be:
 q={!some_query_parser}Cities_France OR Cities_England => q=max(Paris^0.5
Lyon^0.4 "La Defense"^0.3) OR max(London^0.5, Oxford^4)

Implementations possibilities I thought about:

   1. An adapted synonym filter, where query term boosts are encoded as
   payloads.
   2. Query parser that handles the term expansion and weighting. The main
   drawback is the fact it forces me to stick to my own query parser.
   3. Building the query outside Solr.

What would you recommand?

Thanks,
Manuel