fix cast-csv read action for csv field's revisions (#16438)

Co-authored-by: Rijk van Zanten <rijkvanzanten@me.com>

api/src/services/payload.test.ts

@@ -61,6 +61,19 @@ describe('Integration Tests', () => {
 					expect(result).toMatchObject([]);
 				});
 
+				it('Returns array values as is', async () => {
+					const result = await service.transformers['cast-csv']({
+						value: ['test', 'directus'],
+						action: 'read',
+						payload: {},
+						accountability: { role: null },
+						specials: [],
+						helpers,
+					});
+
+					expect(result).toEqual(['test', 'directus']);
+				});
+
 				it('Splits the CSV string', async () => {
 					const result = await service.transformers['cast-csv']({
 						value: 'test,directus',

api/src/services/payload.ts

@@ -121,7 +121,9 @@ export class PayloadService {
 		async 'cast-csv'({ action, value }) {
 			if (Array.isArray(value) === false && typeof value !== 'string') return;
 
-			if (action === 'read' && Array.isArray(value) === false) {
+			if (action === 'read') {
+				if (Array.isArray(value)) return value;
+
 				if (value === '') return [];
 
 				return value.split(',');