Dancer2::Plugin::GraphQL - a plugin for adding GraphQL route handlers


  package MyWebApp;

  use Dancer2;
  use Dancer2::Plugin::GraphQL;
  use GraphQL::Schema;

  my $schema = GraphQL::Schema->from_doc(<<'EOF');
  schema {
    query: QueryRoot
  type QueryRoot {
    helloWorld: String
  graphql '/graphql' => $schema, { helloWorld => 'Hello, world!' };


  # OR, equivalently:
  graphql '/graphql' => $schema => sub {
    my ($app, $body, $execute) = @_;
    # returns JSON-able Perl data
      undef, # $root_value
      undef, # $field_resolver

  # OR, with bespoke user-lookup and caching:
  graphql '/graphql' => sub {
    my ($app, $body, $execute) = @_;
    my $user = MyStuff::User->lookup($app->request->headers->header('X-Token'));
    die "Invalid user\n" if !$user; # turned into GraphQL { errors => [ ... ] }
    my $cached_result = MyStuff::RequestCache->lookup($user, $body->{query});
    return $cached_result if $cached_result;
      undef, # $root_value
      $user, # per-request info
      undef, # $field_resolver


The graphql keyword which is exported by this plugin allow you to define a route handler implementing a GraphQL endpoint.

Parameters, after the route pattern. The first three can be replaced with a single array-ref. If so, the first element is a classname-part, which will be prepended with "GraphQL::Plugin::Convert::". The other values will be passed to that class's "to_graphql" in GraphQL::Plugin::Convert method. The returned hash-ref will be used to set options.


  graphql '/graphql' => [ 'Test' ]; # uses GraphQL::Plugin::Convert::Test

A GraphQL::Schema object.


An optional root value, passed to top-level resolvers.


An optional field resolver, replacing the GraphQL default.


An optional route-handler, replacing the plugin's default - see example above for possibilities.

It must return JSON-able Perl data in the GraphQL format, which is a hash with at least one of a data key and/or an errors key.

If it throws an exception, that will be turned into a GraphQL-formatted error.

If you supply two code-refs, they will be the $resolver and $handler. If you only supply one, it will be $handler. To be certain, pass all four post-pattern arguments.

The route handler code will be compiled to behave like the following:

  • Passes to the GraphQL execute, possibly via your supplied handler, the given schema, $root_value and $field_resolver.

  • The action built matches POST / GET requests.

  • Returns GraphQL results in JSON form.


By default the plugin will not return GraphiQL, but this can be overridden with plugin setting 'graphiql', to true.

Here is example to use GraphiQL:

      graphiql: true


Ed J

Based heavily on Dancer2::Plugin::Ajax by "Dancer Core Developers".


This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.