NAME

GraphQL::AsyncIterator - iterator objects that return promise to next result

SYNOPSIS

  use GraphQL::AsyncIterator;
  my $i = GraphQL::AsyncIterator->new(
    promise_code => $pc,
  );
  # also works when publish happens before next_p called
  my $promised_value = $i->next_p;
  $i->publish('hi'); # now $promised_value will be fulfilled

  $i->close_tap; # now next_p will return undef

DESCRIPTION

Encapsulates the asynchronous event-handling needed for the publish/subscribe behaviour needed by GraphQL::Subscription.

ATTRIBUTES

promise_code

A hash-ref matching "PromiseCode" in GraphQL::Type::Library, which must provide the "new" key.

METHODS

publish(@values)

Resolves the relevant promise with @values.

error(@values)

Rejects the relevant promise with @values.

Returns either a "Promise" in GraphQL::Type::Library of the next value, or "undef" when closed off. Do not call this if a previous promised next value has not been settled, as a queue is not maintained.

The promise will have each of the sets of handlers added by "map_then" appended.

close_tap

Switch to being closed off. "next_p" will return "undef" as soon as it runs out of "publish"ed values. "publish" will throw an exception. NB This will not cause the settling of any outstanding promise returned by "next_p".

map_then($then, $catch)

Adds the handlers to this object's list of handlers, which will be attached to promises returned by "next_p". Returns self.