Over-riding elasticsearch-dsl FacetedSearch to use .filter, not .post_filter for selected facets - see https://twitter.com/simonw/status/797894804700966912

elasticsearch_dsl_facet_override.py

class EmailSearch(FacetedSearch):
    doc_types = [Email]
    # fields that should be searched
    fields = ['subject', 'body']

    facets = {
        'inbox': TermsFacet(field='inbox'),
    }

    def filter(self, search):
        """
        Over-ride default behaviour (which uses post_filter) to use filter instead.
        """
        filters = Q('match_all')
        for f in itervalues(self._filters):
            filters &= f
        return search.filter(filters)