Ed J


GraphQL::Plugin::Convert::OpenAPI - convert OpenAPI schema to GraphQL schema


  use GraphQL::Plugin::Convert::OpenAPI;
  my $converted = GraphQL::Plugin::Convert::OpenAPI->to_graphql(
  print $converted->{schema}->to_doc;


This module implements the GraphQL::Plugin::Convert API to convert a JSON::Validator::OpenAPI specification to GraphQL::Schema etc.

It uses, from the given API spec:

  • the given "definitions" as output types

  • the given "definitions" as input types when required for an input parameter

  • the given operations as fields of either Query if a GET, or Mutation otherwise

If an output type has additionalProperties (effectively a hash whose values are of a specified type), this poses a problem for GraphQL which does not have such a concept. It will be treated as being made up of a list of pairs of objects (i.e. hashes) with two keys: key and value.

The queries will be run against the spec's server. If the spec starts with a /, and a Mojolicious app is supplied (see below), that server will instead be the given app.


To the to_graphql method: a URL to a specification, or a filename containing a JSON specification, or a data structure, of an OpenAPI v2.

Optionally, a Mojolicious app can be given as the second argument. In this case, with a Mojolicious::Lite app, do:

  my $api = plugin OpenAPI => {spec => 'data://main/api.yaml'};
  plugin(GraphQL => {convert => [ 'OpenAPI', $api->validator->bundle, app ]});

with the usual mapping in the case of a full app. For this to work you need Mojolicious::Plugin::OpenAPI version 1.25+, which returns itself on register.



This is available as \&GraphQL::Plugin::Convert::OpenAPI::make_field_resolver in case it is wanted for use outside of the "bundle" of the to_graphql method. It takes arguments:

  • a hash-ref mapping from a GraphQL type-name to another hash-ref with information about that type. There are addition pseudo-types with stored information, named eg TypeName.fieldName, for the obvious purpose. The use of . avoids clashing with real types. This will only have information about input types.

    Valid keys:


    True value if that type needs transforming from a hash into pairs.


    Hash-ref mapping from a GraphQL operation field-name (which will only be done on the Query or Mutation types, for obvious reasons) to an operationId.


    Hash-ref mapping from a GraphQL type's field-name to hash-ref mapping its arguments, if any, to the corresponding GraphQL type-name.


    Hash-ref mapping from a GraphQL type's field-name to the corresponding OpenAPI property-name.


    Boolean value indicating whether the type is a GraphQL::Type::Enum.

and returns a closure that can be used as a field resolver.


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


Ed J, <etj at cpan.org>

Parts based on https://github.com/yarax/swagger-to-graphql


Copyright (C) Ed J

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