fix(Postgres Node): Account for JSON expressions (#12012)

Co-authored-by: Shireen Missi <94372015+ShireenMissi@users.noreply.github.com>

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

@@ -4,6 +4,7 @@ import type {
 	INode,
 	INodeExecutionData,
 	INodePropertyOptions,
+	NodeParameterValueType,
 } from 'n8n-workflow';
 import { NodeOperationError, jsonParse } from 'n8n-workflow';
 
@@ -20,6 +21,23 @@ import type {
 } from './interfaces';
 import { generatePairedItemData } from '../../../../utils/utilities';
 
+export function isJSON(str: string) {
+	try {
+		JSON.parse(str.trim());
+		return true;
+	} catch {
+		return false;
+	}
+}
+
+export function stringToArray(str: NodeParameterValueType | undefined) {
+	if (str === undefined) return [];
+	return String(str)
+		.split(',')
+		.filter((entry) => entry)
+		.map((entry) => entry.trim());
+}
+
 export function wrapData(data: IDataObject | IDataObject[]): INodeExecutionData[] {
 	if (!Array.isArray(data)) {
 		return [{ json: data }];