gqlschema.rb

class MySchema < GraphQL::Schema
  # Required:
  query Types::Query
  # Optional:
  mutation Types::Mutation
  subscription Types::Subscription
end

# app/graphql/types/query_type.rb
class Types::QueryType < GraphQL::Schema::Object
  field :character, Types::CharacterType, resolver: Resolvers::Character
end

# Similarly:
class Types::MutationType < GraphQL::Schema::Object
  # ...
end
# and
class Types::SubscriptionType < GraphQL::Schema::Object
  # ...
end

module Types
  class CharacterType < BaseObject
    field :first_name, String, null: false
    field :last_name, String, null: true    
    field :full_name, String, null: false

    def full_name
      [object.full_name, object.last_name].join(' ')
    end
  end
end

module Types
  class CharacterType < BaseObject
    field :first_name, String, null: false
    field :last_name, String, null: true    
    field :full_name, String, null: false, resolver: Resolvers::CharacterFullName
  end
end





module Resolvers
  class Character < Resolvers::Base
    type Character, null: false

    argument :id, ID, required: true

    def resolve(id:)
      Character.find_by_id(id: id)
    end
  end
end



class Types::CharacterAttributes < Types::BaseInputObject
  argument :first_name, String, required: true
  argument :last_name, String, required: false
  argument :role, Types::RoleEnum, required: false
end

GraphQL.scan(query)

[
  (QUERY "query" [2:1]),
  (LCURLY "{" [2:7]),
  (IDENTIFIER "character" [3:3]),
  (LCURLY "{" [3:13]),
  (IDENTIFIER "firstName" [4:5]),
  (IDENTIFIER "lastName" [5:5]),
  (IDENTIFIER "friends" [6:5]),
  (LCURLY "{" [6:13]),
  (IDENTIFIER "firstName" [7:7]),
  (IDENTIFIER "lastName" [8:7]),
  (RCURLY "}" [9:5]),
  (RCURLY "}" [10:3]),
  (RCURLY "}" [11:1])
]


#<GraphQL::Language::Nodes::Document:0x00007fbd8ae3dec0
 @definitions=
  [#<GraphQL::Language::Nodes::OperationDefinition:0x00007fbd8ae3e0c8
    @col=1,
    @directives=[],
    @filename=nil,
    @line=2,
    @name=nil,
    @operation_type="query",
    @selections=
     [#<GraphQL::Language::Nodes::Field:0x00007fbd8ae3e370
       @alias=nil,
       @arguments=[],
       @col=3,
       @directives=[],
       @filename=nil,
       @line=3,
       @name="character",
       @selections=
        [#<GraphQL::Language::Nodes::Field:0x00007fbd8ae3ff68 @alias=nil, @arguments=[], @col=5, @directives=[], @filename=nil, @line=4, @name="firstName", @selections=[]>,
         #<GraphQL::Language::Nodes::Field:0x00007fbd8ae3fbd0 @alias=nil, @arguments=[], @col=5, @directives=[], @filename=nil, @line=5, @name="lastName", @selections=[]>,
         #<GraphQL::Language::Nodes::Field:0x00007fbd8ae3e5c8
          @alias=nil,
          @arguments=[],
          @col=5,
          @directives=[],
          @filename=nil,
          @line=6,
          @name="friends",
          @selections=
           [#<GraphQL::Language::Nodes::Field:0x00007fbd8ae3f478 @alias=nil, @arguments=[], @col=7, @directives=[], @filename=nil, @line=7, @name="firstName", @selections=[]>,
            #<GraphQL::Language::Nodes::Field:0x00007fbd8ae3eeb0 @alias=nil, @arguments=[], @col=7, @directives=[], @filename=nil, @line=8, @name="lastName", @selections=[]>]>]>],
    @variables=[]>],
 @filename=nil>

             
             
             
            #<GraphQL::Language::Nodes::Field:0x00007fbd8ae3eeb0 @alias=nil, @arguments=[], @col=7, @directives=[], @filename=nil, @line=8, @name="lastName", @selections=[]>]>]>],
    @variables=[]>],
 @filename=nil>