Ruby GraphQL returning union type from query

Question

I want to make a query return a union type

My union type:

class LeadType < ::Types::BaseUnion
  description "Lead"
  possible_types WebsiteLeadType

  def self.resolve_type(object, _context)
    case object.lead_type
    when "website"
      WebsiteLeadType
    else
      raise "Can't find type for lead"
    end
  end
end

I tried to use the type in a query:

class LeadQuery < ::Queries::BaseQuery
  argument :lead_id, ID, required: true, description: "Lead ID"

  type Types::LeadType, null: true

  def resolve(lead_id:, token:)
    lead = Lead.find(lead_id)
  end
end

But I get an error

NameError:
  uninitialized constant Types::BaseEdge

      edge_type_class(Types::BaseEdge)
                           ^^^^^^^^^^
  Did you mean?  Types::BaseField
# ./app/graphql/types/base_object.rb:3:in `<class:BaseObject>'

The query is made available from a query type:

class QueryType < ::Types::BaseObject
  field :lead, resolver: LeadQuery
end

I want to reuse the LeadType union type in other queries and mutations, so the resolve_type logic needs to be reusable and in one file.

Answer 1

A fix is to add the type when adding the query to the main type and remove it from the resolver class

class QueryType < ::Types::BaseObject
  field :lead, Types::LeadType, resolver: LeadQuery
end

class LeadQuery < ::Queries::BaseQuery
  argument :lead_id, ID, required: true, description: "Lead ID"

  def resolve(lead_id:, token:)
    lead = Lead.find(lead_id)
  end
end