Optional list investigation

empty_list.rb

require "bundler/inline"

gemfile do
  gem "racc"
  # gem "graphql", "2.0.16"
  gem "graphql", "2.2.3"
end

class MySchema < GraphQL::Schema
  class Query < GraphQL::Schema::Object
    field :echo, String do
      argument :input, [String], required: false
    end

    def echo(input: :ruby_default_value)
      "#{GraphQL::VERSION}: " + input.inspect
    end
  end

  query(Query)
end

pp MySchema.execute("{ echo }").to_h
pp MySchema.execute("{ echo(input: null) }").to_h
pp MySchema.execute("{ echo(input: []) }").to_h
pp MySchema.execute("{ echo(input: [\"hello\"]) }").to_h

# {"data"=>{"echo"=>"2.0.16: :ruby_default_value"}}
# {"data"=>{"echo"=>"2.0.16: nil"}}
# {"data"=>{"echo"=>"2.0.16: []"}}
# {"data"=>{"echo"=>"2.0.16: [\"hello\"]"}}

# {"data"=>{"echo"=>"2.2.3: :ruby_default_value"}}
# {"data"=>{"echo"=>"2.2.3: nil"}}
# {"data"=>{"echo"=>"2.2.3: []"}}
# {"data"=>{"echo"=>"2.2.3: [\"hello\"]"}}