1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
|
package GraphQL::Subscription;
use 5.014;
use strict;
use warnings;
use Types::Standard -all;
use Types::TypeTiny -all;
use GraphQL::Type::Library -all;
use GraphQL::MaybeTypeCheck;
use GraphQL::Language::Parser qw(parse);
use GraphQL::Error;
use GraphQL::Debug qw(_debug);
require GraphQL::Execution;
use Exporter 'import';
=head1 NAME
GraphQL::Subscription - Implement GraphQL subscriptions
=cut
our @EXPORT_OK = qw(
subscribe
);
our $VERSION = '0.02';
use constant DEBUG => $ENV{GRAPHQL_DEBUG}; # "DEBUG and" gets optimised out if false
=head1 SYNOPSIS
use GraphQL::Subscription qw(subscribe);
my $result = subscribe($schema, $doc, $root_value);
=head1 DESCRIPTION
Implements a GraphQL "subscription" - a feed of events, commonly of
others' mutations.
=head1 METHODS
=head2 subscribe
my $result = subscribe(
$schema,
$doc, # can also be AST
$root_value,
$context_value,
$variable_values,
$operation_name,
$field_resolver,
$promise_code,
$subscribe_resolver,
);
Takes the same args as L<GraphQL::Execution/execute>, except
that the C<$promise_code> is mandatory, and there is the optional
C<$subscribe_resolver> which, supplied or not, will be used instead
of the C<$field_resolver> to resolve the initial subscription. The
C<$field_resolver> will still be used for resolving each result.
Returns a promise of either:
=over
=item *
an error result if the subscription fails (generated by GraphQL)
=item *
a L<GraphQL::AsyncIterator> instance generated by a resolver, probably
hooked up to a L<GraphQL::PubSub> instance
=back
The event source returns values by using
L<GraphQL::AsyncIterator/publish>. To communicate errors, resolvers
can throw errors in the normal way, or at the top level, use
L<GraphQL::AsyncIterator/error>.
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.
=cut
fun subscribe(
(InstanceOf['GraphQL::Schema']) $schema,
Str | ArrayRef[HashRef] $doc,
Any $root_value,
Any $context_value,
Maybe[HashRef] $variable_values,
Maybe[Str] $operation_name,
Maybe[CodeLike] $field_resolver,
PromiseCode $promise_code,
Maybe[CodeLike] $subscribe_resolver = undef,
) :ReturnType(Promise) {
die 'Must supply $promise_code' if !$promise_code;
my $result = eval {
my $ast;
my $context = eval {
$ast = ref($doc) ? $doc : parse($doc);
GraphQL::Execution::_build_context(
$schema,
$ast,
$root_value,
$context_value,
$variable_values,
$operation_name,
$subscribe_resolver,
$promise_code,
);
};
DEBUG and _debug('subscribe', $context, $@);
die $@ if $@;
# from GraphQL::Execution::_execute_operation
my $operation = $context->{operation};
my $op_type = $operation->{operationType} || 'subscription';
my $type = $context->{schema}->$op_type;
my ($fields) = $type->_collect_fields(
$context,
$operation->{selections},
[[], {}],
{},
);
DEBUG and _debug('subscribe(fields)', $fields, $root_value);
# from GraphQL::Execution::_execute_fields
my ($field_names, $nodes_defs) = @$fields;
die "Subscription needs to have only one field; got (@$field_names)\n"
if @$field_names != 1;
my $result_name = $field_names->[0];
my $nodes = $nodes_defs->{$result_name};
my $field_node = $nodes->[0];
my $field_name = $field_node->{name};
my $field_def = GraphQL::Execution::_get_field_def($context->{schema}, $type, $field_name);
DEBUG and _debug('subscribe(resolve)', $type->to_string, $nodes, $root_value, $field_def);
die "The subscription field '$field_name' is not defined\n"
if !$field_def;
my $resolve = $field_def->{subscribe} || $context->{field_resolver};
my $path = [ $result_name ];
my $info = GraphQL::Execution::_build_resolve_info(
$context,
$type,
$field_def,
$path,
$nodes,
);
my $result = GraphQL::Execution::_resolve_field_value_or_error(
$context,
$field_def,
$nodes,
$resolve,
$root_value,
$info,
);
DEBUG and _debug('subscribe(result)', $result, $@);
die "The subscription field '$field_name' returned non-AsyncIterator '$result'\n"
if !is_AsyncIterator($result);
$result->map_then(
sub {
GraphQL::Execution::execute(
$schema,
$ast,
$_[0],
$context_value,
$variable_values,
$operation_name,
$field_resolver,
$promise_code,
)
},
sub {
my ($error) = @_;
die $error if !GraphQL::Error->is($error);
GraphQL::Execution::_build_response(GraphQL::Execution::_wrap_error($error));
},
);
};
$result = GraphQL::Execution::_build_response(GraphQL::Execution::_wrap_error($@)) if $@;
$promise_code->{resolve}->($result);
}
1;
|
