fix(Postgres Node): Accommodate null values in query parameters for expressions (#13544)

packages/nodes-base/nodes/Postgres/test/v2/operations.test.ts

@@ -363,6 +363,26 @@ describe('Test PostgresV2, executeQuery operation', () => {
 		);
 	});
 
+	it('should execute queries with null key/value pairs', async () => {
+		const nodeParameters: IDataObject = {
+			operation: 'executeQuery',
+			query: 'SELECT *\nFROM users\nWHERE username IN ($1, $2)',
+			options: {
+				queryReplacement: '"={{ betty }}, {{ null }}"',
+			},
+		};
+		const nodeOptions = nodeParameters.options as IDataObject;
+
+		expect(async () => {
+			await executeQuery.execute.call(
+				createMockExecuteFunction(nodeParameters),
+				runQueries,
+				items,
+				nodeOptions,
+			);
+		}).not.toThrow();
+	});
+
 	it('should execute queries with multiple json key/value pairs', async () => {
 		const nodeParameters: IDataObject = {
 			operation: 'executeQuery',

packages/nodes-base/nodes/Postgres/test/v2/utils.test.ts

@@ -17,6 +17,7 @@ import {
 	isJSON,
 	convertValuesToJsonWithPgp,
 	hasJsonDataTypeInSchema,
+	evaluateExpression,
 } from '../../v2/helpers/utils';
 
 const node: INode = {
@@ -39,6 +40,25 @@ describe('Test PostgresV2, isJSON', () => {
 	});
 });
 
+describe('Test PostgresV2, evaluateExpression', () => {
+	it('should evaluate undefined to an empty string', () => {
+		expect(evaluateExpression(undefined)).toEqual('');
+	});
+	it('should evaluate null to a string with value null', () => {
+		expect(evaluateExpression(null)).toEqual('null');
+	});
+	it('should evaluate object to a string', () => {
+		expect(evaluateExpression({ key: '' })).toEqual('{"key":""}');
+		expect(evaluateExpression([])).toEqual('[]');
+		expect(evaluateExpression([1, 2, 4])).toEqual('[1,2,4]');
+	});
+	it('should evaluate everything else to a string', () => {
+		expect(evaluateExpression(1)).toEqual('1');
+		expect(evaluateExpression('string')).toEqual('string');
+		expect(evaluateExpression(true)).toEqual('true');
+	});
+});
+
 describe('Test PostgresV2, wrapData', () => {
 	it('should wrap object in json', () => {
 		const data = {