How to create text index in mongoid 5?

I have this in my model

index({company_name: 1, first_name: 1, last_name: 1 })

Model.text_search 'something'

gives this error

Mongo::Error::OperationFailure: text index required for $text query

I found the solution

index({company_name: 'text', first_name: 'text', last_name: 'text' })

You just have to pass 'text' instead of 1.