fix(GraphQL Node): Prevent duplicate error items in error output routing

packages/nodes-base/nodes/GraphQL/GraphQL.node.ts

@@ -514,6 +514,46 @@ export class GraphQL implements INodeType {
 				} else {
 					response = await this.helpers.request(requestOptions);
 				}
+
+				// Parse string responses
+				if (typeof response === 'string' && responseFormat !== 'string') {
+					try {
+						response = JSON.parse(response);
+					} catch (error) {
+						throw new NodeOperationError(
+							this.getNode(),
+							'Response body is not valid JSON. Change "Response Format" to "String"',
+							{ itemIndex },
+						);
+					}
+				}
+
+				// Check for GraphQL errors BEFORE adding to returnItems
+				let parsedForErrorCheck = response;
+				if (typeof response === 'string') {
+					try {
+						parsedForErrorCheck = JSON.parse(response);
+					} catch {
+						// Not JSON, no errors to check
+						parsedForErrorCheck = response;
+					}
+				}
+
+				if (
+					typeof parsedForErrorCheck === 'object' &&
+					parsedForErrorCheck !== null &&
+					'errors' in parsedForErrorCheck
+				) {
+					const errors = parsedForErrorCheck.errors;
+					if (Array.isArray(errors) && errors.length > 0) {
+						const message =
+							errors.map((error: IDataObject) => error.message).join(', ') || 'Unexpected error';
+						const errorPayload: JsonObject = { errors };
+						throw new NodeApiError(this.getNode(), errorPayload, { message });
+					}
+				}
+
+				// Only add to returnItems if there are no GraphQL errors
 				if (responseFormat === 'string') {
 					const dataPropertyName = this.getNodeParameter('dataPropertyName', 0);
 					returnItems.push({
@@ -522,41 +562,12 @@ export class GraphQL implements INodeType {
 						},
 					});
 				} else {
-					if (typeof response === 'string') {
-						try {
-							response = JSON.parse(response);
-						} catch (error) {
-							throw new NodeOperationError(
-								this.getNode(),
-								'Response body is not valid JSON. Change "Response Format" to "String"',
-								{ itemIndex },
-							);
-						}
-					}
-
 					const executionData = this.helpers.constructExecutionMetaData(
 						this.helpers.returnJsonArray(response as IDataObject),
 						{ itemData: { item: itemIndex } },
 					);
 					returnItems.push(...executionData);
 				}
-
-				// parse error string messages
-				if (typeof response === 'string' && response.startsWith('{"errors":')) {
-					try {
-						const errorResponse = JSON.parse(response) as IDataObject;
-						if (Array.isArray(errorResponse.errors)) {
-							response = errorResponse;
-						}
-					} catch (e) {}
-				}
-				// throw from response object.errors[]
-				if (typeof response === 'object' && response.errors) {
-					const message =
-						response.errors?.map((error: IDataObject) => error.message).join(', ') ||
-						'Unexpected error';
-					throw new NodeApiError(this.getNode(), response.errors as JsonObject, { message });
-				}
 			} catch (error) {
 				if (!this.continueOnFail()) {
 					throw error;
@@ -565,10 +576,10 @@ export class GraphQL implements INodeType {
 				const errorData = this.helpers.returnJsonArray({
 					error: error.message,
 				});
-				const exectionErrorWithMetaData = this.helpers.constructExecutionMetaData(errorData, {
+				const executionErrorWithMetaData = this.helpers.constructExecutionMetaData(errorData, {
 					itemData: { item: itemIndex },
 				});
-				returnItems.push(...exectionErrorWithMetaData);
+				returnItems.push(...executionErrorWithMetaData);
 			}
 		}
 		return [returnItems];

packages/nodes-base/nodes/GraphQL/test/GraphQL.node.test.ts

@@ -110,4 +110,49 @@ describe('GraphQL Node', () => {
 			credentials,
 		});
 	});
+
+	describe('error output routing with continueOnFail', () => {
+		const baseUrl = 'http://test.example.com';
+
+		// Mock the first request that returns a GraphQL error
+		nock(baseUrl)
+			.post('/graphql', '{"query":"INVALID_QUERY","variables":{},"operationName":null}')
+			.reply(200, {
+				errors: [
+					{
+						message: 'Syntax Error: Invalid query syntax',
+						extensions: {
+							code: 'GRAPHQL_PARSE_FAILED',
+						},
+					},
+				],
+			});
+
+		// Mock the second request that returns successful data
+		nock(baseUrl)
+			.post(
+				'/graphql',
+				'{"query":"query { users { id name email } }","variables":{},"operationName":null}',
+			)
+			.reply(200, {
+				data: {
+					users: [
+						{
+							id: '1',
+							name: 'John Doe',
+							email: '[email protected]',
+						},
+						{
+							id: '2',
+							name: 'Jane Smith',
+							email: '[email protected]',
+						},
+					],
+				},
+			});
+
+		new NodeTestHarness().setupTests({
+			workflowFiles: ['workflow.error_output_routing.json'],
+		});
+	});
 });

packages/nodes-base/nodes/GraphQL/test/workflow.error_output_routing.json

@@ -0,0 +1,119 @@
+{
+	"name": "Test GraphQL Error Output Routing",
+	"nodes": [
+		{
+			"parameters": {},
+			"id": "manual-trigger",
+			"name": "Manual Trigger",
+			"type": "n8n-nodes-base.manualTrigger",
+			"typeVersion": 1,
+			"position": [0, 0]
+		},
+		{
+			"parameters": {
+				"jsCode": "return [\n  // This query will fail with a GraphQL error\n  {\n    query: 'INVALID_QUERY'\n  },\n  // This query will succeed\n  {\n    query: 'query { users { id name email } }'\n  }\n]"
+			},
+			"id": "code-node",
+			"name": "Generate Queries",
+			"type": "n8n-nodes-base.code",
+			"typeVersion": 2,
+			"position": [200, 0]
+		},
+		{
+			"parameters": {
+				"endpoint": "http://test.example.com/graphql",
+				"query": "={{ $json.query }}"
+			},
+			"id": "graphql-node",
+			"name": "GraphQL",
+			"type": "n8n-nodes-base.graphql",
+			"typeVersion": 1.1,
+			"position": [400, 0],
+			"onError": "continueErrorOutput"
+		},
+		{
+			"parameters": {},
+			"id": "success-output",
+			"name": "Success Output",
+			"type": "n8n-nodes-base.noOp",
+			"typeVersion": 1,
+			"position": [600, -100]
+		},
+		{
+			"parameters": {},
+			"id": "error-output",
+			"name": "Error Output",
+			"type": "n8n-nodes-base.noOp",
+			"typeVersion": 1,
+			"position": [600, 100]
+		}
+	],
+	"connections": {
+		"Manual Trigger": {
+			"main": [
+				[
+					{
+						"node": "Generate Queries",
+						"type": "main",
+						"index": 0
+					}
+				]
+			]
+		},
+		"Generate Queries": {
+			"main": [
+				[
+					{
+						"node": "GraphQL",
+						"type": "main",
+						"index": 0
+					}
+				]
+			]
+		},
+		"GraphQL": {
+			"main": [
+				[
+					{
+						"node": "Success Output",
+						"type": "main",
+						"index": 0
+					}
+				],
+				[
+					{
+						"node": "Error Output",
+						"type": "main",
+						"index": 0
+					}
+				]
+			]
+		}
+	},
+	"pinData": {
+		"Success Output": [
+			{
+				"data": {
+					"users": [
+						{
+							"id": "1",
+							"name": "John Doe",
+							"email": "[email protected]"
+						},
+						{
+							"id": "2",
+							"name": "Jane Smith",
+							"email": "[email protected]"
+						}
+					]
+				}
+			}
+		],
+		"Error Output": [
+			{
+				"query": "INVALID_QUERY",
+				"error": "Syntax Error: Invalid query syntax"
+			}
+		]
+	}
+}