RootFilterField in Wagtail -- enables you to index the field without the specific page model string prefix

elasticsearch7.py

from wagtail.search.backends.elasticsearch7 import (
    Elasticsearch7Mapping,
    Elasticsearch7SearchBackend,
    Elasticsearch7SearchQueryCompiler,
    Elasticsearch7SearchResults,
)

from .index import RootFilterField


class SearchMapping(Elasticsearch7Mapping):
    def get_field_mapping(self, field):
        name, mapping = super().get_field_mapping(field)

        if isinstance(field, RootFilterField):
            if mapping["type"] == "string":
                mapping["type"] = self.keyword_type

            if self.set_index_not_analyzed_on_filter_fields:
                # Not required on ES5+ as that uses the "keyword" type for
                # filtered string fields
                mapping["index"] = "not_analyzed"

            mapping["include_in_all"] = False
        return name, mapping

    def get_field_column_name(self, field):
        if isinstance(field, RootFilterField):
            return field.get_attname(self.model) + "_filter"

        return super().get_field_column_name(field)


class SearchQueryCompiler(Elasticsearch7SearchQueryCompiler):
    mapping_class = SearchMapping


class SearchBackend(Elasticsearch7SearchBackend):
    mapping_class = SearchMapping
    query_compiler_class = SearchQueryCompiler
    results_class = Elasticsearch7SearchResults

index.py

from wagtail.search.backends.elasticsearch5 import get_model_root
from wagtail.search.index import BaseField


class RootFilterField(BaseField):
    def get_definition_model(self, cls):
        return get_model_root(cls)