graphql_resolver_example.rb

# app/graphql/types/category_type.rb

class CategoryType < GraphQL::Schema::Object
  field :key, String, null: true
  field :name, String, null: false
  field :icon_url, String, null: true
  field :related_categories, 
        [CategoryType],
        null: false,
        resolver: Resolvers::RelatedCategoryResolver
  
  def name
    object.display_name
  end
  
  def icon_url
    CategoryResolver.icon_url(object, context)
  end
end

class CategoryResolver
  # ...
  def icon_url(object, context)
    # business logic here
    object.icon&.image_url
  end
  # ...
end