1👍
You should create template in:
templates\search\indexes\APP_NAME\company_text.txt
what represent searchable fields from you CompanyIndex
{{ object.text }}
{{ object.name }}
{{ object.sector }}
Whatever you write in template will be searched from your indexes regardless it is present in search_index.py or not.
Following is enough to make an index.
text = CharField(document=True, use_template=True)
Source:stackexchange.com