NAME

       GraphQL::Subscription - Implement GraphQL subscriptions

SYNOPSIS

         use GraphQL::Subscription qw(subscribe);
         my $result = subscribe($schema, $doc, $root_value);

DESCRIPTION

       Implements a GraphQL "subscription" - a feed of events, commonly of others' mutations.

METHODS

   subscribe
         my $result = subscribe(
           $schema,
           $doc, # can also be AST
           $root_value,
           $context_value,
           $variable_values,
           $operation_name,
           $field_resolver,
           $promise_code,
           $subscribe_resolver,
         );

       Takes the same args as "execute" in GraphQL::Execution, except that the $promise_code is
       mandatory, and there is the optional $subscribe_resolver which, supplied or not, will be
       used instead of the $field_resolver to resolve the initial subscription. The
       $field_resolver will still be used for resolving each result.

       Returns a promise of either:

       •   an error result if the subscription fails (generated by GraphQL)

       •   a GraphQL::AsyncIterator instance generated by a resolver, probably hooked up to a
           GraphQL::PubSub instance

       The event source returns values by using "publish" in GraphQL::AsyncIterator. To
       communicate errors, resolvers can throw errors in the normal way, or at the top level, use
       "error" in GraphQL::AsyncIterator.

       The values will be resolved in the normal GraphQL fashion, including that if there is no
       specific-to-field resolver, it must be a value acceptable to the supplied or default
       field-resolver, typically a hash-ref with a key of the field's name.