Accessing directives in the Schema SDL with GraphQL-Ruby

example.rb

require "graphql"

# A schema definition with field-level directives
schema = GraphQL::Schema.from_definition <<-GRAPHQL
type Query {
  totalScore: Int! @mock
}

type Mutation {
  incrementScore(by: Int = 1): Int! @mock(with: "SomeClassName")
}
GRAPHQL

# Accessing the directive names
total_score_field = schema.types["Query"].fields["totalScore"]
directive_nodes = total_score_field.ast_node.directives
p directive_nodes.map(&:name)
# ["mock"]

# An example accessing the arguments of a directive
increment_score_field = schema.types["Mutation"].fields["incrementScore"]
directive_nodes = increment_score_field.ast_node.directives
directive_nodes.each do |dir|
  args = dir.arguments.map { |a| "#{a.name} => #{a.value}" }
  puts "#{dir.name}(#{args.join(",")})"
  # mock(with => SomeClassName)
end

@rmosolgo thanks for this. Is it possible to output each type’s SDL from an existing Ruby schema?

It's not super-well supported, but it's possible using Schema::Printer:

https://github.com/rmosolgo/graphql-ruby/blob/a750b69733424b3af8808fc4c9e00cbee3511c5d/lib/graphql/schema/printer.rb#L36-L37