jsutils: Add generic Path implementation

src/execution/execute.js

@@ -14,6 +14,7 @@ import promiseForObject from '../jsutils/promiseForObject';
 import promiseReduce from '../jsutils/promiseReduce';
 import { type ObjMap } from '../jsutils/ObjMap';
 import { type PromiseOrValue } from '../jsutils/PromiseOrValue';
+import { type Path, addPath, pathToArray } from '../jsutils/Path';
 
 import { getOperationRootType } from '../utilities/getOperationRootType';
 import { typeFromAST } from '../utilities/typeFromAST';
@@ -32,7 +33,6 @@ import {
   type GraphQLFieldResolver,
   type GraphQLResolveInfo,
   type GraphQLTypeResolver,
-  type ResponsePath,
   type GraphQLList,
   isObjectType,
   isAbstractType,
@@ -235,30 +235,6 @@ function buildResponse(
     : { errors: exeContext.errors, data };
 }
 
-/**
- * Given a ResponsePath (found in the `path` entry in the information provided
- * as the last argument to a field resolver), return an Array of the path keys.
- */
-export function responsePathAsArray(
-  path: ResponsePath,
-): $ReadOnlyArray<string | number> {
-  const flattened = [];
-  let curr = path;
-  while (curr) {
-    flattened.push(curr.key);
-    curr = curr.prev;
-  }
-  return flattened.reverse();
-}
-
-/**
- * Given a ResponsePath and a key, return a new ResponsePath containing the
- * new key.
- */
-export function addPath(prev: ResponsePath | void, key: string | number) {
-  return { prev, key };
-}
-
 /**
  * Essential assertions before executing to provide developer feedback for
  * improper use of the GraphQL library.
@@ -420,7 +396,7 @@ function executeFieldsSerially(
   exeContext: ExecutionContext,
   parentType: GraphQLObjectType,
   sourceValue: mixed,
-  path: ResponsePath | void,
+  path: Path | void,
   fields: ObjMap<Array<FieldNode>>,
 ): PromiseOrValue<ObjMap<mixed>> {
   return promiseReduce(
@@ -459,7 +435,7 @@ function executeFields(
   exeContext: ExecutionContext,
   parentType: GraphQLObjectType,
   sourceValue: mixed,
-  path: ResponsePath | void,
+  path: Path | void,
   fields: ObjMap<Array<FieldNode>>,
 ): PromiseOrValue<ObjMap<mixed>> {
   const results = Object.create(null);
@@ -639,7 +615,7 @@ function resolveField(
   parentType: GraphQLObjectType,
   source: mixed,
   fieldNodes: $ReadOnlyArray<FieldNode>,
-  path: ResponsePath,
+  path: Path,
 ): PromiseOrValue<mixed> {
   const fieldNode = fieldNodes[0];
   const fieldName = fieldNode.name.value;
@@ -685,7 +661,7 @@ export function buildResolveInfo(
   fieldDef: GraphQLField<mixed, mixed>,
   fieldNodes: $ReadOnlyArray<FieldNode>,
   parentType: GraphQLObjectType,
-  path: ResponsePath,
+  path: Path,
 ): GraphQLResolveInfo {
   // The resolve function's optional fourth argument is a collection of
   // information about the current execution state.
@@ -751,7 +727,7 @@ function completeValueCatchingError(
   returnType: GraphQLOutputType,
   fieldNodes: $ReadOnlyArray<FieldNode>,
   info: GraphQLResolveInfo,
-  path: ResponsePath,
+  path: Path,
   result: mixed,
 ): PromiseOrValue<mixed> {
   try {
@@ -788,7 +764,7 @@ function handleFieldError(rawError, fieldNodes, path, returnType, exeContext) {
   const error = locatedError(
     asErrorInstance(rawError),
     fieldNodes,
-    responsePathAsArray(path),
+    pathToArray(path),
   );
 
   // If the field type is non-nullable, then it is resolved without any
@@ -829,7 +805,7 @@ function completeValue(
   returnType: GraphQLOutputType,
   fieldNodes: $ReadOnlyArray<FieldNode>,
   info: GraphQLResolveInfo,
-  path: ResponsePath,
+  path: Path,
   result: mixed,
 ): PromiseOrValue<mixed> {
   // If result is an Error, throw a located error.
@@ -922,7 +898,7 @@ function completeListValue(
   returnType: GraphQLList<GraphQLOutputType>,
   fieldNodes: $ReadOnlyArray<FieldNode>,
   info: GraphQLResolveInfo,
-  path: ResponsePath,
+  path: Path,
   result: mixed,
 ): PromiseOrValue<$ReadOnlyArray<mixed>> {
   invariant(
@@ -982,7 +958,7 @@ function completeAbstractValue(
   returnType: GraphQLAbstractType,
   fieldNodes: $ReadOnlyArray<FieldNode>,
   info: GraphQLResolveInfo,
-  path: ResponsePath,
+  path: Path,
   result: mixed,
 ): PromiseOrValue<ObjMap<mixed>> {
   const resolveTypeFn = returnType.resolveType || exeContext.typeResolver;
@@ -1066,7 +1042,7 @@ function completeObjectValue(
   returnType: GraphQLObjectType,
   fieldNodes: $ReadOnlyArray<FieldNode>,
   info: GraphQLResolveInfo,
-  path: ResponsePath,
+  path: Path,
   result: mixed,
 ): PromiseOrValue<ObjMap<mixed>> {
   // If there is an isTypeOf predicate function, call it with the
@@ -1119,7 +1095,7 @@ function collectAndExecuteSubfields(
   exeContext: ExecutionContext,
   returnType: GraphQLObjectType,
   fieldNodes: $ReadOnlyArray<FieldNode>,
-  path: ResponsePath,
+  path: Path,
   result: mixed,
 ): PromiseOrValue<ObjMap<mixed>> {
   // Collect sub-fields to execute to complete this value.

src/execution/index.js

@@ -1,11 +1,8 @@
 // @flow strict
 
-export {
-  execute,
-  defaultFieldResolver,
-  defaultTypeResolver,
-  responsePathAsArray,
-} from './execute';
+export { pathToArray as responsePathAsArray } from '../jsutils/Path';
+
+export { execute, defaultFieldResolver, defaultTypeResolver } from './execute';
 export type { ExecutionArgs, ExecutionResult } from './execute';
 
 export { getDirectiveValues } from './values';

src/jsutils/Path.js

@@ -0,0 +1,26 @@
+// @flow strict
+
+export type Path = {|
+  +prev: Path | void,
+  +key: string | number,
+|};
+
+/**
+ * Given a Path and a key, return a new Path containing the new key.
+ */
+export function addPath(prev: $ReadOnly<Path> | void, key: string | number) {
+  return { prev, key };
+}
+
+/**
+ * Given a Path, return an Array of the path keys.
+ */
+export function pathToArray(path: $ReadOnly<Path>): Array<string | number> {
+  const flattened = [];
+  let curr = path;
+  while (curr) {
+    flattened.push(curr.key);
+    curr = curr.prev;
+  }
+  return flattened.reverse();
+}

src/subscription/subscribe.js

@@ -2,19 +2,18 @@
 
 import { isAsyncIterable } from 'iterall';
 import inspect from '../jsutils/inspect';
+import { addPath, pathToArray } from '../jsutils/Path';
 import { GraphQLError } from '../error/GraphQLError';
 import { locatedError } from '../error/locatedError';
 import {
   type ExecutionResult,
-  addPath,
   assertValidExecutionArguments,
   buildExecutionContext,
   buildResolveInfo,
   collectFields,
   execute,
   getFieldDef,
   resolveFieldValueOrError,
-  responsePathAsArray,
 } from '../execution/execute';
 import { type GraphQLSchema } from '../type/schema';
 import mapAsyncIterator from './mapAsyncIterator';
@@ -269,9 +268,7 @@ export function createSourceEventStream(
       // If eventStream is an Error, rethrow a located error.
       if (eventStream instanceof Error) {
         return {
-          errors: [
-            locatedError(eventStream, fieldNodes, responsePathAsArray(path)),
-          ],
+          errors: [locatedError(eventStream, fieldNodes, pathToArray(path))],
         };
       }
 

src/type/definition.js

@@ -15,6 +15,7 @@ import keyValMap from '../jsutils/keyValMap';
 import mapValue from '../jsutils/mapValue';
 import isObjectLike from '../jsutils/isObjectLike';
 import { type ObjMap } from '../jsutils/ObjMap';
+import { type Path } from '../jsutils/Path';
 import { Kind } from '../language/kinds';
 import { valueFromASTUntyped } from '../utilities/valueFromASTUntyped';
 import {
@@ -859,19 +860,14 @@ export type GraphQLResolveInfo = {|
   +fieldNodes: $ReadOnlyArray<FieldNode>,
   +returnType: GraphQLOutputType,
   +parentType: GraphQLObjectType,
-  +path: ResponsePath,
+  +path: Path,
   +schema: GraphQLSchema,
   +fragments: ObjMap<FragmentDefinitionNode>,
   +rootValue: mixed,
   +operation: OperationDefinitionNode,
   +variableValues: { [variable: string]: mixed, ... },
 |};
 
-export type ResponsePath = {|
-  +prev: ResponsePath | void,
-  +key: string | number,
-|};
-
 export type GraphQLFieldConfig<
   TSource,
   TContext,

src/type/index.js

@@ -1,5 +1,7 @@
 // @flow strict
 
+export type { Path as ResponsePath } from '../jsutils/Path';
+
 export {
   // Predicate
   isSchema,
@@ -150,7 +152,6 @@ export type {
   GraphQLIsTypeOfFn,
   GraphQLObjectTypeConfig,
   GraphQLResolveInfo,
-  ResponsePath,
   GraphQLScalarTypeConfig,
   GraphQLTypeResolver,
   GraphQLUnionTypeConfig,

src/utilities/coerceValue.js

@@ -6,6 +6,7 @@ import inspect from '../jsutils/inspect';
 import didYouMean from '../jsutils/didYouMean';
 import isObjectLike from '../jsutils/isObjectLike';
 import suggestionList from '../jsutils/suggestionList';
+import { type Path, addPath, pathToArray } from '../jsutils/Path';
 import { GraphQLError } from '../error/GraphQLError';
 import { type ASTNode } from '../language/ast';
 import {
@@ -22,8 +23,6 @@ type CoercedValue = {|
   +value: mixed,
 |};
 
-type Path = {| +prev: Path | void, +key: string | number |};
-
 /**
  * Coerces a JavaScript value given a GraphQL Type.
  *
@@ -108,12 +107,11 @@ export function coerceValue(
       let errors;
       const coercedValue = [];
       forEach((value: any), (itemValue, index) => {
-        const itemPath = { prev: path, key: index };
         const coercedItem = coerceValue(
           itemValue,
           itemType,
           blameNode,
-          itemPath,
+          addPath(path, index),
         );
         if (coercedItem.errors) {
           errors = add(errors, coercedItem.errors);
@@ -144,7 +142,7 @@ export function coerceValue(
 
     // Ensure every defined field is valid.
     for (const field of objectValues(fields)) {
-      const fieldPath = { prev: path, key: field.name };
+      const fieldPath = addPath(path, field.name);
       const fieldValue = value[field.name];
       if (fieldValue === undefined) {
         if (field.defaultValue !== undefined) {
@@ -215,14 +213,11 @@ function coercionError(message, blameNode, path, subMessage, originalError) {
 
   // Build a string describing the path into the value where the error was found
   if (path) {
-    const segmentStrings = [];
-    for (let currentPath = path; currentPath; currentPath = currentPath.prev) {
-      const { key } = currentPath;
-      segmentStrings.unshift(
-        typeof key === 'string' ? '.' + key : '[' + key.toString() + ']',
-      );
+    fullMessage += ' at value';
+    for (const key of pathToArray(path)) {
+      fullMessage +=
+        typeof key === 'string' ? '.' + key : '[' + key.toString() + ']';
     }
-    fullMessage += ' at value' + segmentStrings.join('');
   }
 
   fullMessage += subMessage ? '.' + subMessage : '.';