use undefined for empty

Author: yaacovCR

src/execution/IncrementalPublisher.ts

@@ -174,7 +174,7 @@ export interface FormattedCompletedResult {
 export function buildIncrementalResponse(
   context: IncrementalPublisherContext,
   result: ObjMap<unknown>,
-  errors: ReadonlyArray<GraphQLError>,
+  errors: ReadonlyArray<GraphQLError> | undefined,
   incrementalDataRecords: ReadonlyArray<IncrementalDataRecord>,
 ): ExperimentalIncrementalExecutionResults {
   const incrementalPublisher = new IncrementalPublisher(context);
@@ -186,7 +186,7 @@ export function buildIncrementalResponse(
 }
 
 interface IncrementalPublisherContext {
-  cancellableStreams: Set<StreamRecord>;
+  cancellableStreams?: Set<StreamRecord> | undefined;
 }
 
 /**
@@ -220,7 +220,7 @@ class IncrementalPublisher {
 
   buildResponse(
     data: ObjMap<unknown>,
-    errors: ReadonlyArray<GraphQLError>,
+    errors: ReadonlyArray<GraphQLError> | undefined,
     incrementalDataRecords: ReadonlyArray<IncrementalDataRecord>,
   ): ExperimentalIncrementalExecutionResults {
     this._addIncrementalDataRecords(incrementalDataRecords);
@@ -229,7 +229,7 @@ class IncrementalPublisher {
     const pending = this._pendingSourcesToResults();
 
     const initialResult: InitialIncrementalExecutionResult =
-      errors.length === 0
+      errors === undefined
         ? { data, pending, hasNext: true }
         : { errors, data, pending, hasNext: true };
 
@@ -441,8 +441,12 @@ class IncrementalPublisher {
     };
 
     const returnStreamIterators = async (): Promise<void> => {
+      const cancellableStreams = this._context.cancellableStreams;
+      if (cancellableStreams === undefined) {
+        return;
+      }
       const promises: Array<Promise<unknown>> = [];
-      for (const streamRecord of this._context.cancellableStreams) {
+      for (const streamRecord of cancellableStreams) {
         if (streamRecord.earlyReturn !== undefined) {
           promises.push(streamRecord.earlyReturn());
         }
@@ -516,7 +520,7 @@ class IncrementalPublisher {
       );
     }
 
-    if (deferredGroupedFieldSetResult.incrementalDataRecords.length > 0) {
+    if (deferredGroupedFieldSetResult.incrementalDataRecords !== undefined) {
       this._addIncrementalDataRecords(
         deferredGroupedFieldSetResult.incrementalDataRecords,
       );
@@ -586,14 +590,20 @@ class IncrementalPublisher {
     if (streamItemsResult.result === undefined) {
       this._completed.push({ id });
       this._pending.delete(streamRecord);
-      this._context.cancellableStreams.delete(streamRecord);
+      const cancellableStreams = this._context.cancellableStreams;
+      if (cancellableStreams !== undefined) {
+        cancellableStreams.delete(streamRecord);
+      }
     } else if (streamItemsResult.result === null) {
       this._completed.push({
         id,
         errors: streamItemsResult.errors,
       });
       this._pending.delete(streamRecord);
-      this._context.cancellableStreams.delete(streamRecord);
+      const cancellableStreams = this._context.cancellableStreams;
+      if (cancellableStreams !== undefined) {
+        cancellableStreams.delete(streamRecord);
+      }
       streamRecord.earlyReturn?.().catch(() => {
         /* c8 ignore next 1 */
         // ignore error
@@ -606,7 +616,7 @@ class IncrementalPublisher {
 
       this._incremental.push(incrementalEntry);
 
-      if (streamItemsResult.incrementalDataRecords.length > 0) {
+      if (streamItemsResult.incrementalDataRecords !== undefined) {
         this._addIncrementalDataRecords(
           streamItemsResult.incrementalDataRecords,
         );
@@ -663,7 +673,7 @@ function isDeferredGroupedFieldSetRecord(
 export interface IncrementalContext {
   deferUsageSet: DeferUsageSet | undefined;
   path: Path | undefined;
-  errors: Array<GraphQLError>;
+  errors?: Array<GraphQLError> | undefined;
 }
 
 export type DeferredGroupedFieldSetResult =
@@ -680,7 +690,7 @@ interface ReconcilableDeferredGroupedFieldSetResult {
   deferredFragmentRecords: ReadonlyArray<DeferredFragmentRecord>;
   path: Array<string | number>;
   result: BareDeferredGroupedFieldSetResult;
-  incrementalDataRecords: ReadonlyArray<IncrementalDataRecord>;
+  incrementalDataRecords: ReadonlyArray<IncrementalDataRecord> | undefined;
   sent?: true | undefined;
 }
 
@@ -718,7 +728,6 @@ export class DeferredGroupedFieldSetRecord {
     const incrementalContext: IncrementalContext = {
       deferUsageSet,
       path,
-      errors: [],
     };
 
     for (const deferredFragmentRecord of deferredFragmentRecords) {
@@ -786,7 +795,7 @@ interface NonReconcilableStreamItemsResult {
 interface NonTerminatingStreamItemsResult {
   streamRecord: StreamRecord;
   result: BareStreamItemsResult;
-  incrementalDataRecords: ReadonlyArray<IncrementalDataRecord>;
+  incrementalDataRecords: ReadonlyArray<IncrementalDataRecord> | undefined;
 }
 
 interface TerminatingStreamItemsResult {
@@ -826,7 +835,6 @@ export class StreamItemsRecord {
     const incrementalContext: IncrementalContext = {
       deferUsageSet: undefined,
       path: itemPath,
-      errors: [],
     };
 
     this._result = executor(incrementalContext);
@@ -850,7 +858,7 @@ export class StreamItemsRecord {
       ? {
           ...result,
           incrementalDataRecords:
-            result.incrementalDataRecords.length === 0
+            result.incrementalDataRecords === undefined
               ? [this.nextStreamItems]
               : [this.nextStreamItems, ...result.incrementalDataRecords],
         }

src/execution/execute.ts

@@ -141,8 +141,8 @@ export interface ExecutionContext {
   fieldResolver: GraphQLFieldResolver<any, any>;
   typeResolver: GraphQLTypeResolver<any, any>;
   subscribeFieldResolver: GraphQLFieldResolver<any, any>;
-  errors: Array<GraphQLError>;
-  cancellableStreams: Set<StreamRecord>;
+  errors: Array<GraphQLError> | undefined;
+  cancellableStreams: Set<StreamRecord> | undefined;
 }
 
 export interface ExecutionArgs {
@@ -163,7 +163,7 @@ export interface StreamUsage {
   fieldGroup: FieldGroup;
 }
 
-type GraphQLResult<T> = [T, ReadonlyArray<IncrementalDataRecord>];
+type GraphQLResult<T> = [T, ReadonlyArray<IncrementalDataRecord> | undefined];
 
 const UNEXPECTED_EXPERIMENTAL_DIRECTIVES =
   'The provided schema unexpectedly contains experimental directives (@defer or @stream). These directives may only be utilized if experimental execution features are explicitly enabled.';
@@ -329,20 +329,20 @@ function executeOperation(
 }
 
 function withError(
-  errors: Array<GraphQLError>,
+  errors: Array<GraphQLError> | undefined,
   error: GraphQLError,
 ): ReadonlyArray<GraphQLError> {
-  return errors.length === 0 ? [error] : [...errors, error];
+  return errors === undefined ? [error] : [...errors, error];
 }
 
 function buildDataResponse(
   exeContext: ExecutionContext,
   data: ObjMap<unknown>,
-  incrementalDataRecords: ReadonlyArray<IncrementalDataRecord>,
+  incrementalDataRecords: ReadonlyArray<IncrementalDataRecord> | undefined,
 ): ExecutionResult | ExperimentalIncrementalExecutionResults {
   const { errors } = exeContext;
-  if (incrementalDataRecords.length === 0) {
-    return errors.length > 0 ? { errors, data } : { data };
+  if (incrementalDataRecords === undefined) {
+    return errors !== undefined ? { errors, data } : { data };
   }
 
   return buildIncrementalResponse(
@@ -454,8 +454,8 @@ export function buildExecutionContext(
     fieldResolver: fieldResolver ?? defaultFieldResolver,
     typeResolver: typeResolver ?? defaultTypeResolver,
     subscribeFieldResolver: subscribeFieldResolver ?? defaultFieldResolver,
-    errors: [],
-    cancellableStreams: new Set(),
+    errors: undefined,
+    cancellableStreams: undefined,
   };
 }
 
@@ -466,7 +466,7 @@ function buildPerEventExecutionContext(
   return {
     ...exeContext,
     rootValue: payload,
-    errors: [],
+    errors: undefined,
   };
 }
 
@@ -552,16 +552,16 @@ function executeFieldsSerially(
       appendNewIncrementalDataRecords(acc, result[1]);
       return acc;
     },
-    [Object.create(null), []] as GraphQLResult<ObjMap<unknown>>,
+    [Object.create(null), undefined] as GraphQLResult<ObjMap<unknown>>,
   );
 }
 
 function appendNewIncrementalDataRecords(
   acc: GraphQLResult<unknown>,
-  newRecords: ReadonlyArray<IncrementalDataRecord>,
+  newRecords: ReadonlyArray<IncrementalDataRecord> | undefined,
 ): void {
-  if (newRecords.length > 0) {
-    acc[1] = acc[1].length === 0 ? newRecords : [...acc[1], ...newRecords];
+  if (newRecords !== undefined) {
+    acc[1] = acc[1] === undefined ? newRecords : [...acc[1], ...newRecords];
   }
 }
 
@@ -721,7 +721,7 @@ function executeField(
           path,
           incrementalContext,
         );
-        return [null, []];
+        return [null, undefined];
       });
     }
     return completed;
@@ -734,7 +734,7 @@ function executeField(
       path,
       incrementalContext,
     );
-    return [null, []];
+    return [null, undefined];
   }
 }
 
@@ -783,7 +783,13 @@ function handleFieldError(
 
   // Otherwise, error protection is applied, logging the error and resolving
   // a null value for this field if one is encountered.
-  (incrementalContext ?? exeContext).errors.push(error);
+  const context = incrementalContext ?? exeContext;
+  let errors = context.errors;
+  if (errors === undefined) {
+    errors = [];
+    context.errors = errors;
+  }
+  errors.push(error);
 }
 
 /**
@@ -845,7 +851,7 @@ function completeValue(
 
   // If result value is null or undefined then return null.
   if (result == null) {
-    return [null, []];
+    return [null, undefined];
   }
 
   // If field type is List, complete each item in the list with the inner type
@@ -865,7 +871,7 @@ function completeValue(
   // If field type is a leaf type, Scalar or Enum, serialize to a valid value,
   // returning null if serialization is not possible.
   if (isLeafType(returnType)) {
-    return [completeLeafValue(returnType, result), []];
+    return [completeLeafValue(returnType, result), undefined];
   }
 
   // If field type is an abstract type, Interface or Union, determine the
@@ -940,7 +946,7 @@ async function completePromisedValue(
       path,
       incrementalContext,
     );
-    return [null, []];
+    return [null, undefined];
   }
 }
 
@@ -1030,7 +1036,7 @@ async function completeAsyncIteratorValue(
 ): Promise<GraphQLResult<ReadonlyArray<unknown>>> {
   let containsPromise = false;
   const completedResults: Array<unknown> = [];
-  const acc: GraphQLResult<Array<unknown>> = [completedResults, []];
+  const acc: GraphQLResult<Array<unknown>> = [completedResults, undefined];
   let index = 0;
   // eslint-disable-next-line no-constant-condition
   while (true) {
@@ -1107,7 +1113,7 @@ async function completeAsyncIteratorValueWithPossibleStream(
 ): Promise<GraphQLResult<ReadonlyArray<unknown>>> {
   let containsPromise = false;
   const completedResults: Array<unknown> = [];
-  const acc: GraphQLResult<Array<unknown>> = [completedResults, []];
+  const acc: GraphQLResult<Array<unknown>> = [completedResults, undefined];
   let index = 0;
   const initialCount = streamUsage.initialCount;
   // eslint-disable-next-line no-constant-condition
@@ -1119,6 +1125,9 @@ async function completeAsyncIteratorValueWithPossibleStream(
         earlyReturn: asyncIterator.return?.bind(asyncIterator),
       });
 
+      if (exeContext.cancellableStreams === undefined) {
+        exeContext.cancellableStreams = new Set();
+      }
       exeContext.cancellableStreams.add(streamRecord);
 
       const firstStreamItems = firstAsyncStreamItems(
@@ -1300,7 +1309,7 @@ function completeIterableValue(
   // where the list contains no Promises by avoiding creating another Promise.
   let containsPromise = false;
   const completedResults: Array<unknown> = [];
-  const acc: GraphQLResult<Array<unknown>> = [completedResults, []];
+  const acc: GraphQLResult<Array<unknown>> = [completedResults, undefined];
   let index = 0;
   for (const item of items) {
     // No need to modify the info object containing the path,
@@ -1361,7 +1370,7 @@ function completeIterableValueWithPossibleStream(
   // where the list contains no Promises by avoiding creating another Promise.
   let containsPromise = false;
   const completedResults: Array<unknown> = [];
-  const acc: GraphQLResult<Array<unknown>> = [completedResults, []];
+  const acc: GraphQLResult<Array<unknown>> = [completedResults, undefined];
   let index = 0;
   const initialCount = streamUsage.initialCount;
   const iterator = items[Symbol.iterator]();
@@ -2332,7 +2341,7 @@ function buildDeferredGroupedFieldSetResult(
     deferredFragmentRecords,
     path: pathToArray(path),
     result:
-      errors.length === 0 ? { data: result[0] } : { data: result[0], errors },
+      errors === undefined ? { data: result[0] } : { data: result[0], errors },
     incrementalDataRecords: result[1],
   };
 }
@@ -2548,7 +2557,7 @@ function completeStreamItems(
           itemPath,
           incrementalContext,
         );
-        return [null, []] as GraphQLResult<unknown>;
+        return [null, undefined] as GraphQLResult<unknown>;
       })
       .then(
         (resolvedItem) =>
@@ -2587,7 +2596,7 @@ function completeStreamItems(
         itemPath,
         incrementalContext,
       );
-      result = [null, []];
+      result = [null, undefined];
     }
   } catch (error) {
     return {
@@ -2608,7 +2617,7 @@ function completeStreamItems(
           itemPath,
           incrementalContext,
         );
-        return [null, []] as GraphQLResult<unknown>;
+        return [null, undefined] as GraphQLResult<unknown>;
       })
       .then(
         (resolvedItem) =>
@@ -2637,7 +2646,7 @@ function buildStreamItemsResult(
   return {
     streamRecord,
     result:
-      errors.length === 0
+      errors === undefined
         ? { items: [result[0]] }
         : {
             items: [result[0]],