Get a top-level argument from a nested field in GraphQL-Ruby

top_level_argument.rb

require "bundler/inline"

gemfile do
  gem "graphql", "2.4.4"
end

class MySchema < GraphQL::Schema
  class NestedThingInput < GraphQL::Schema::InputObject
    argument :env, String
  end

  class NestedThing < GraphQL::Schema::Object
    field :nested, NestedThing do
      argument :input, NestedThingInput, required: false
    end

    def nested(input: nil)
      # Add this value to scoped context so that it will be available to child fields
      # see https://graphql-ruby.org/queries/executing_queries.html#scoped-context
      if input
        context.scoped_set!(:top_level_env, input.env)
      end
      :some_nested_thing
    end

    field :top_level_env, String

    def top_level_env
      # This will have been set by _something_ upstream in the query:
      context[:top_level_env]
    end
  end

  class Query < GraphQL::Schema::Object
    field :nested, NestedThing do
      argument :input, NestedThingInput, required: false
    end

    def nested(input: nil)
      # This is duplicated from NestedThing#nested -- you could use your DRY technique of choice here.
      if input
        context.scoped_set!(:top_level_env, input.env)
      end
      :some_nested_thing
    end

  end

  query(Query)
end


# Access the value with shallow nesting:
pp MySchema.execute("{ nested(input: { env: \"staging\" }) { nested { topLevelEnv } } }").to_h
# {"data"=>{"nested"=>{"nested"=>{"topLevelEnv"=>"staging"}}}}

# Access the value with no nesting:
pp MySchema.execute("{ nested(input: { env: \"production\" }) { topLevelEnv } }").to_h
# {"data"=>{"nested"=>{"topLevelEnv"=>"production"}}}

# Access the value with very deep nesting, with an override in the tree:
pp MySchema.execute("{ nested(input: { env: \"ignored\" }) { nested { nested { nested(input: { env: \"local-override\" }) { topLevelEnv } } } } }").to_h
# {"data"=>{"nested"=>{"nested"=>{"nested"=>{"nested"=>{"topLevelEnv"=>"local-override"}}}}}}