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Return underlying AsyncIterators when execute result is returned (#2843)
# Conflicts: # src/execution/execute.ts
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2 files changed

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-9
lines changed

2 files changed

+277
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‎src/execution/__tests__/stream-test.ts

Lines changed: 248 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1,3 +1,4 @@
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import { assert } from 'chai';
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import { describe, it } from 'mocha';
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34
import { expectJSON } from '../../__testUtils__/expectJSON';
@@ -162,6 +163,37 @@ const query = new GraphQLObjectType({
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yield await Promise.resolve({ string: friends[1].name });
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},
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},
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asyncIterableListDelayed: {
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type: new GraphQLList(friendType),
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async *resolve() {
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for (const friend of friends) {
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// pause an additional ms before yielding to allow time
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// for tests to return or throw before next value is processed.
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// eslint-disable-next-line no-await-in-loop
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await resolveOnNextTick();
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yield friend; /* c8 ignore start */
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// Not reachable, early return
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}
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} /* c8 ignore stop */,
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},
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asyncIterableListNoReturn: {
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type: new GraphQLList(friendType),
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resolve() {
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let i = 0;
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return {
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[Symbol.asyncIterator]: () => ({
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async next() {
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const friend = friends[i++];
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if (friend) {
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await resolveOnNextTick();
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return { value: friend, done: false };
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}
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return { value: undefined, done: true };
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},
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}),
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};
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},
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},
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asyncIterableListDelayedClose: {
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type: new GraphQLList(friendType),
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async *resolve() {
@@ -1344,4 +1376,220 @@ describe('Execute: stream directive', () => {
13441376
},
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]);
13461378
});
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it('Returns underlying async iterables when returned generator is returned', async () => {
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const document = parse(`
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query {
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asyncIterableListDelayed @stream(initialCount: 1) {
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id
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... @defer {
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name
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}
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}
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}
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`);
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const schema = new GraphQLSchema({ query });
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1392+
const executeResult = await execute({ schema, document, rootValue: {} });
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assert(isAsyncIterable(executeResult));
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const iterator = executeResult[Symbol.asyncIterator]();
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1396+
const result1 = await iterator.next();
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expectJSON(result1).toDeepEqual({
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done: false,
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value: {
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data: {
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asyncIterableListDelayed: [
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{
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id: '1',
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},
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],
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},
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hasNext: true,
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},
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});
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const returnPromise = iterator.return();
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// these results had started processing before return was called
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const result2 = await iterator.next();
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expectJSON(result2).toDeepEqual({
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done: false,
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value: {
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incremental: [
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{
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data: {
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name: 'Luke',
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},
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path: ['asyncIterableListDelayed', 0],
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},
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],
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hasNext: true,
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},
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});
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const result3 = await iterator.next();
1429+
expectJSON(result3).toDeepEqual({
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done: false,
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value: {
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incremental: [
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{
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items: [
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{
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id: '2',
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},
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],
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path: ['asyncIterableListDelayed', 1],
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},
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],
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hasNext: true,
1443+
},
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});
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const result4 = await iterator.next();
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expectJSON(result4).toDeepEqual({
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done: true,
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value: undefined,
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});
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await returnPromise;
1451+
});
1452+
it('Can return async iterable when underlying iterable does not have a return method', async () => {
1453+
const document = parse(`
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query {
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asyncIterableListNoReturn @stream(initialCount: 1) {
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name
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id
1458+
}
1459+
}
1460+
`);
1461+
const schema = new GraphQLSchema({ query });
1462+
1463+
const executeResult = await execute({ schema, document, rootValue: {} });
1464+
assert(isAsyncIterable(executeResult));
1465+
const iterator = executeResult[Symbol.asyncIterator]();
1466+
1467+
const result1 = await iterator.next();
1468+
expectJSON(result1).toDeepEqual({
1469+
done: false,
1470+
value: {
1471+
data: {
1472+
asyncIterableListNoReturn: [
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{
1474+
id: '1',
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name: 'Luke',
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},
1477+
],
1478+
},
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hasNext: true,
1480+
},
1481+
});
1482+
1483+
const returnPromise = iterator.return();
1484+
1485+
// this result had started processing before return was called
1486+
const result2 = await iterator.next();
1487+
expectJSON(result2).toDeepEqual({
1488+
done: false,
1489+
value: {
1490+
incremental: [
1491+
{
1492+
items: [
1493+
{
1494+
id: '2',
1495+
name: 'Han',
1496+
},
1497+
],
1498+
path: ['asyncIterableListNoReturn', 1],
1499+
},
1500+
],
1501+
hasNext: true,
1502+
},
1503+
});
1504+
1505+
// third result is not returned because async iterator has returned
1506+
const result3 = await iterator.next();
1507+
expectJSON(result3).toDeepEqual({
1508+
done: true,
1509+
value: undefined,
1510+
});
1511+
await returnPromise;
1512+
});
1513+
it('Returns underlying async iterables when returned generator is thrown', async () => {
1514+
const document = parse(`
1515+
query {
1516+
asyncIterableListDelayed @stream(initialCount: 1) {
1517+
... @defer {
1518+
name
1519+
}
1520+
id
1521+
}
1522+
}
1523+
`);
1524+
const schema = new GraphQLSchema({ query });
1525+
1526+
const executeResult = await execute({ schema, document, rootValue: {} });
1527+
assert(isAsyncIterable(executeResult));
1528+
const iterator = executeResult[Symbol.asyncIterator]();
1529+
1530+
const result1 = await iterator.next();
1531+
expectJSON(result1).toDeepEqual({
1532+
done: false,
1533+
value: {
1534+
data: {
1535+
asyncIterableListDelayed: [
1536+
{
1537+
id: '1',
1538+
},
1539+
],
1540+
},
1541+
hasNext: true,
1542+
},
1543+
});
1544+
1545+
const throwPromise = iterator.throw(new Error('bad'));
1546+
1547+
// these results had started processing before return was called
1548+
const result2 = await iterator.next();
1549+
expectJSON(result2).toDeepEqual({
1550+
done: false,
1551+
value: {
1552+
incremental: [
1553+
{
1554+
data: {
1555+
name: 'Luke',
1556+
},
1557+
path: ['asyncIterableListDelayed', 0],
1558+
},
1559+
],
1560+
hasNext: true,
1561+
},
1562+
});
1563+
const result3 = await iterator.next();
1564+
expectJSON(result3).toDeepEqual({
1565+
done: false,
1566+
value: {
1567+
incremental: [
1568+
{
1569+
items: [
1570+
{
1571+
id: '2',
1572+
},
1573+
],
1574+
path: ['asyncIterableListDelayed', 1],
1575+
},
1576+
],
1577+
hasNext: true,
1578+
},
1579+
});
1580+
1581+
// this result is not returned because async iterator has returned
1582+
const result4 = await iterator.next();
1583+
expectJSON(result4).toDeepEqual({
1584+
done: true,
1585+
value: undefined,
1586+
});
1587+
try {
1588+
await throwPromise; /* c8 ignore start */
1589+
// Not reachable, always throws
1590+
/* c8 ignore stop */
1591+
} catch (e) {
1592+
// ignore error
1593+
}
1594+
});
13471595
});

‎src/execution/execute.ts

Lines changed: 29 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -1747,6 +1747,7 @@ async function executeStreamIterator(
17471747
label,
17481748
path: fieldPath,
17491749
parentContext,
1750+
iterator,
17501751
});
17511752

17521753
const dataPromise = executeStreamIteratorItem(
@@ -1789,6 +1790,7 @@ function yieldSubsequentPayloads(
17891790
initialResult: ExecutionResult,
17901791
): AsyncGenerator<AsyncExecutionResult, void, void> {
17911792
let _hasReturnedInitialResult = false;
1793+
let isDone = false;
17921794

17931795
async function race(): Promise<IteratorResult<AsyncExecutionResult>> {
17941796
if (exeContext.subsequentPayloads.length === 0) {
@@ -1866,19 +1868,37 @@ function yieldSubsequentPayloads(
18661868
},
18671869
done: false,
18681870
});
1869-
} else if (exeContext.subsequentPayloads.length === 0) {
1871+
} else if (exeContext.subsequentPayloads.length === 0 || isDone) {
18701872
return Promise.resolve({ value: undefined, done: true });
18711873
}
18721874
return race();
18731875
},
1874-
// TODO: implement return & throw
1875-
// c8 ignore next 2
1876-
// will be covered in follow up
1877-
return: () => Promise.resolve({ value: undefined, done: true }),
1878-
1879-
// c8 ignore next 2
1880-
// will be covered in follow up
1881-
throw: (error?: unknown) => Promise.reject(error),
1876+
async return(): Promise<IteratorResult<AsyncExecutionResult, void>> {
1877+
await Promise.all(
1878+
exeContext.subsequentPayloads.map((asyncPayloadRecord) => {
1879+
if (isStreamPayload(asyncPayloadRecord)) {
1880+
return asyncPayloadRecord.iterator?.return?.();
1881+
}
1882+
return undefined;
1883+
}),
1884+
);
1885+
isDone = true;
1886+
return { value: undefined, done: true };
1887+
},
1888+
async throw(
1889+
error?: unknown,
1890+
): Promise<IteratorResult<AsyncExecutionResult, void>> {
1891+
await Promise.all(
1892+
exeContext.subsequentPayloads.map((asyncPayloadRecord) => {
1893+
if (isStreamPayload(asyncPayloadRecord)) {
1894+
return asyncPayloadRecord.iterator?.return?.();
1895+
}
1896+
return undefined;
1897+
}),
1898+
);
1899+
isDone = true;
1900+
return Promise.reject(error);
1901+
},
18821902
};
18831903
}
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