NAME

       GraphQL - Perl implementation of GraphQL

SYNOPSIS

         use GraphQL::Schema;
         use GraphQL::Type::Object;
         use GraphQL::Type::Scalar qw($String);
         use GraphQL::Execution qw(execute);

         my $schema = GraphQL::Schema->from_doc(<<'EOF');
         type Query {
           helloWorld: String
         }
         EOF
         post '/graphql' => sub {
           send_as JSON => execute(
             $schema,
             body_parameters->{query},
             { helloWorld => 'Hello world!' },
             undef,
             body_parameters->{variables},
             body_parameters->{operationName},
             undef,
           );
         };

       The above is from the sample Dancer 2 applet <https://github.com/graphql-perl/sample-
       dancer2>.

DESCRIPTION

       This module is a port of the GraphQL reference implementation, graphql-js
       <https://github.com/graphql-js/graphql-js>, to Perl 5.

       It now supports Promises, allowing asynchronous operation. See
       Mojolicious::Plugin::GraphQL for an example of how to take advantage of this.

       As of 0.39, supports GraphQL subscriptions.

       See GraphQL::Type for description of how to create GraphQL types.

   Introduction to GraphQL
       GraphQL is a technology that lets clients talk to APIs via a single endpoint, which acts
       as a single "source of the truth". This means clients do not need to seek the whole
       picture from several APIs. Additionally, it makes this efficient in network traffic, time,
       and programming effort:

       Network traffic
           The request asks for exactly what it wants, which it gets, and no more. No wasted
           traffic.

       Time
           It gets all the things it needs in one go, including any connected resources, so it
           does not need to make several requests to fill its information requirement.

       Programming effort
           With "fragments" that can be attached to user-interface components, keeping track of
           what information a whole page needs to request can be automated. See Relay
           <https://facebook.github.io/relay/> or Apollo <http://dev.apollodata.com/> for more on
           this.

   Basic concepts
       GraphQL implements a system featuring a schema, which features various classes of types,
       some of which are objects. Special objects provide the roots of queries (mandatory), and
       mutations and subscriptions (both optional).

       Objects have fields, each of which can be specified to take arguments, and which have a
       return type. These are effectively the properties and/or methods on the type. If they
       return an object, then a query can specify subfields of that object, and so on - as
       alluded to in the "time-saving" point above.

       For more, see the JavaScript tutorial in "SEE ALSO".

   Hooking your system up to GraphQL
       You will need to decide how to model your system in GraphQL terms. This will involve
       deciding on what output object types you have, what fields they have, and what arguments
       and return-types those fields have.

       Additionally, you will need to design mutations if you want to be able to
       update/create/delete data. This requires some thought for return types, to ensure you can
       get all the information you need to proceed to avoid extra round-trips.

       The easiest way to achieve these things is to make a GraphQL::Plugin::Convert subclass, to
       encapsulate the specifics of your system. See the documentation for further information.

       Finally, you should consider whether you need "subscriptions". These are designed to hook
       into WebSockets. Apollo has a JavaScript module <https://github.com/apollographql/graphql-
       subscriptions> for this.

       Specifying types and fields is straightforward. See the document for how to make
       resolvers.

DEBUGGING

       To debug, set environment variable "GRAPHQL_DEBUG" to a true value.

EXPORT

       None yet.

SEE ALSO

       SQL::Translator::Producer::GraphQL - produce GraphQL schemas from a DBIx::Class::Schema
       (or in fact any SQL database)

       GraphQL::Plugin::Convert::DBIC - produce working GraphQL schema from a DBIx::Class::Schema

       GraphQL::Plugin::Convert::OpenAPI - produce working GraphQL schema from an OpenAPI
       specification

       Sample Mojolicious OpenAPI to GraphQL applet <https://github.com/graphql-perl/sample-
       mojolicious-openapi>

       Sample Dancer 2 applet <https://github.com/graphql-perl/sample-dancer2>

       Sample Mojolicious applet <https://github.com/graphql-perl/sample-mojolicious>

       Dancer2::Plugin::GraphQL

       Mojolicious::Plugin::GraphQL

       <http://facebook.github.io/graphql/> - GraphQL specification

       <http://graphql.org/graphql-js/> - Tutorial on the JavaScript version, highly recommended.
       Translation to graphql-perl <http://blogs.perl.org/users/ed_j/2017/10/graphql-
       perl---graphql-js-tutorial-translation-to-graphql-perl-and-mojoliciousplugingraphql.html>.

AUTHOR

       Ed J, "<etj at cpan.org>"

BUGS

       Please report any bugs or feature requests on
       <https://github.com/graphql-perl/graphql-perl/issues>.

       Or, if you prefer email and/or RT: to "bug-graphql at rt.cpan.org", or through the web
       interface at <http://rt.cpan.org/NoAuth/ReportBug.html?Queue=GraphQL>. I will be notified,
       and then you'll automatically be notified of progress on your bug as I make changes.

ACKNOWLEDGEMENTS

       The creation of this work has been sponsored by Perl Careers: <https://perl.careers/>.

       Artur Khabibullin "<rtkh at cpan.org>" contributed valuable ports of the JavaScript tests.

       The creation of the subscriptions functionality in this work has been sponsored by
       Sanctus.app: <https://sanctus.app>.

LICENSE AND COPYRIGHT

       Copyright 2017 Ed J.

       This program is free software; you can redistribute it and/or modify it under the terms of
       the the Artistic License (2.0). You may obtain a copy of the full license at:

       <http://www.perlfoundation.org/artistic_license_2_0>