Mojolicious::Plugin::GraphQL - a plugin for adding GraphQL route handlers
my $schema = GraphQL::Schema->from_doc(<<'EOF'); schema { query: QueryRoot } type QueryRoot { helloWorld: String } EOF # for Mojolicious substitute "plugin" with $app->plugin(... # Mojolicious::Lite (with endpoint under "/graphql") plugin GraphQL => { schema => $schema, root_value => { helloWorld => 'Hello, world!' } }; # OR, equivalently: plugin GraphQL => {schema => $schema, handler => sub { my ($c, $body, $execute, $subscribe_fn) = @_; # returns JSON-able Perl data $execute->( $schema, $body->{query}, { helloWorld => 'Hello, world!' }, # $root_value $c->req->headers, $body->{variables}, $body->{operationName}, undef, # $field_resolver $subscribe_fn ? (undef, $subscribe_fn) : (), # only passed for subs ); }}; # OR, with bespoke user-lookup and caching: plugin GraphQL => {schema => $schema, handler => sub { my ($c, $body, $execute, $subscribe_fn) = @_; 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 $cached_result; MyStuff::RequestCache->cache_and_return($execute->( $schema, $body->{query}, undef, # $root_value $user, # per-request info $body->{variables}, $body->{operationName}, undef, # $field_resolver $subscribe_fn ? (undef, $subscribe_fn) : (), # only passed for subs )); }; # With GraphiQL, on /graphql plugin GraphQL => {schema => $schema, graphiql => 1};
This plugin allows you to easily define a route handler implementing a GraphQL endpoint, including a websocket for subscriptions following Apollo's subscriptions-transport-ws protocol.
subscriptions-transport-ws
As of version 0.09, it will supply the necessary promise_code parameter to "execute" in GraphQL::Execution. This means your resolvers can (and indeed should) return Promise objects to function asynchronously. As of 0.15 these must be "Promises/A+" as subscriptions require resolve and reject methods.
promise_code
resolve
reject
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. Note as above that the wrapper used in this plugin will supply the hash-ref matching "PromiseCode" in GraphQL::Type::Library.
$root_value
$field_resolver
The action built matches POST / GET requests.
Returns GraphQL results in JSON form.
Mojolicious::Plugin::GraphQL supports the following options.
Array-ref. 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, particularly schema, and probably at least one of resolver and root_value.
schema
resolver
root_value
String. Defaults to /graphql.
/graphql
A GraphQL::Schema object. As of 0.15, must be supplied.
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.
data
errors
If it throws an exception, that will be turned into a GraphQL-formatted error.
If being used for a subscription, it will be called with a fourth parameter as shown above. It is safe to not handle this if you are content with GraphQL's defaults.
Boolean controlling whether requesting the endpoint with Accept: text/html will return the GraphiQL user interface. Defaults to false.
Accept: text/html
# Mojolicious::Lite plugin GraphQL => {schema => $schema, graphiql => 1};
Defaults to 0, which means do not send. Otherwise will send a keep-alive packet over websocket every specified number of seconds.
Mojolicious::Plugin::GraphQL inherits all methods from Mojolicious::Plugin and implements the following new ones.
my $route = $plugin->register(Mojolicious->new, {schema => $schema});
Register renderer in Mojolicious application.
Exportable is the function promise_code, which returns a hash-ref suitable for passing as the 8th argument to "execute" in GraphQL::Execution.
To use subscriptions within your web app, just insert this JavaScript:
<script src="//unpkg.com/subscriptions-transport-ws@0.9.16/browser/client.js"></script> # ... const subscriptionsClient = new window.SubscriptionsTransportWs.SubscriptionClient(websocket_uri, { reconnect: true }); subscriptionsClient.request({ query: "subscription s($c: [String!]) {subscribe(channels: $c) {channel username dateTime message}}", variables: { c: channel }, }).subscribe({ next(payload) { var msg = payload.data.subscribe; console.log(msg.username + ' said', msg.message); }, error: console.error, });
Note the use of parameterised queries, where you only need to change the variables parameter. The above is adapted from the sample app, https://github.com/graphql-perl/sample-mojolicious.
variables
GraphQL
GraphQL::Plugin::Convert
https://github.com/apollographql/subscriptions-transport-ws#client-browser - Apollo documentation
Ed J
Based heavily on Mojolicious::Plugin::PODRenderer.
This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.
To install Mojolicious::Plugin::GraphQL, copy and paste the appropriate command in to your terminal.
cpanm
cpanm Mojolicious::Plugin::GraphQL
CPAN shell
perl -MCPAN -e shell install Mojolicious::Plugin::GraphQL
For more information on module installation, please visit the detailed CPAN module installation guide.