Simplify collectFields for @defer & @stream

Author: robrichard

src/execution/IncrementalPublisher.ts

@@ -1,3 +1,4 @@
+import { invariant } from '../jsutils/invariant.js';
 import type { ObjMap } from '../jsutils/ObjMap.js';
 import type { Path } from '../jsutils/Path.js';
 import { pathToArray } from '../jsutils/Path.js';
@@ -8,7 +9,7 @@ import type {
   GraphQLFormattedError,
 } from '../error/GraphQLError.js';
 
-import type { GroupedFieldSet } from './collectFields.js';
+import type { DeferUsage, GroupedFieldSet } from './collectFields.js';
 
 interface IncrementalUpdate<TData = unknown, TExtensions = ObjMap<unknown>> {
   pending: ReadonlyArray<PendingResult>;
@@ -609,16 +610,23 @@ export class IncrementalPublisher {
     deferredGroupedFieldSetRecord: DeferredGroupedFieldSetRecord,
   ): IncrementalDeferResult {
     const { data, deferredFragmentRecords } = deferredGroupedFieldSetRecord;
-    let maxLength = deferredFragmentRecords[0].path.length;
-    let maxIndex = 0;
-    for (let i = 1; i < deferredFragmentRecords.length; i++) {
+    let maxLength;
+    let maxIndex;
+    for (let i = 0; i < deferredFragmentRecords.length; i++) {
       const deferredFragmentRecord = deferredFragmentRecords[i];
+      if (deferredFragmentRecord.id == null) {
+        continue;
+      }
       const length = deferredFragmentRecord.path.length;
-      if (length > maxLength) {
+      if (typeof maxLength !== 'number' || length > maxLength) {
         maxLength = length;
         maxIndex = i;
       }
     }
+    invariant(
+      typeof maxIndex === 'number',
+      'No id for deferred incremental result',
+    );
     const recordWithLongestPath = deferredFragmentRecords[maxIndex];
     const longestPath = recordWithLongestPath.path;
     const subPath = deferredGroupedFieldSetRecord.path.slice(
@@ -763,7 +771,6 @@ export class DeferredGroupedFieldSetRecord {
   path: ReadonlyArray<string | number>;
   deferredFragmentRecords: ReadonlyArray<DeferredFragmentRecord>;
   groupedFieldSet: GroupedFieldSet;
-  shouldInitiateDefer: boolean;
   errors: Array<GraphQLError>;
   data: ObjMap<unknown> | undefined;
   sent: boolean;
@@ -772,12 +779,10 @@ export class DeferredGroupedFieldSetRecord {
     path: Path | undefined;
     deferredFragmentRecords: ReadonlyArray<DeferredFragmentRecord>;
     groupedFieldSet: GroupedFieldSet;
-    shouldInitiateDefer: boolean;
   }) {
     this.path = pathToArray(opts.path);
     this.deferredFragmentRecords = opts.deferredFragmentRecords;
     this.groupedFieldSet = opts.groupedFieldSet;
-    this.shouldInitiateDefer = opts.shouldInitiateDefer;
     this.errors = [];
     this.sent = false;
   }
@@ -786,6 +791,7 @@ export class DeferredGroupedFieldSetRecord {
 /** @internal */
 export class DeferredFragmentRecord {
   path: ReadonlyArray<string | number>;
+  deferUsage: DeferUsage;
   label: string | undefined;
   id: string | undefined;
   children: Set<SubsequentResultRecord>;
@@ -795,9 +801,10 @@ export class DeferredFragmentRecord {
   pendingSent?: boolean;
   _pending: Set<DeferredGroupedFieldSetRecord>;
 
-  constructor(opts: { path: Path | undefined; label: string | undefined }) {
+  constructor(opts: { path: Path | undefined; deferUsage: DeferUsage }) {
     this.path = pathToArray(opts.path);
-    this.label = opts.label;
+    this.label = opts.deferUsage.label;
+    this.deferUsage = opts.deferUsage;
     this.children = new Set();
     this.filtered = false;
     this.deferredGroupedFieldSetRecords = new Set();