Use the Wagtail search backend's autocomplete() search method where suitable

[ababic]

Models that subclass wagtail.search.index.Indexed very often have the optimal search matching criteria / weighting configured on the model using the search_fields attribute.

If using one of these models with AutocompletePanel, it's difficult to imagine a scenario where you wouldn't just want to reuse this configuration for an admin-facing search too. This would be possible with something like:

from wagtail.search.index import Indexed
from wagtail.search.backends import get_search_backend

@require_POST
def search(request):
    ...
    if issubclass(model, Indexed):
        backend = get_search_backend()
        try:
            matches = backend.autocomplete(search_query, model)
        except NotImplementedError:
            matches = backend.search(search_query, model)
    else:
         # continue with existing behaviour