add date formatter example

api/src/graphql/events.sdl.ts

@@ -19,6 +19,14 @@ export const schema = gql`
     capacity: Int
     createdAt: DateTime!
     updatedAt: DateTime!
+
+    formattedStartAt: String
+    formattedEndAt: String
+    formattedRegistrationStartAt: String
+    formattedRegistrationEndAt: String
+    formattedCreatedAt: String
+    formattedUpdatedAt: String
+
     sessions: [EventSession]
     speakers: [EventSpeaker]
     registrants: [EventRegistrant]

api/src/lib/formatters.ts

@@ -0,0 +1,7 @@
+import { utcToZonedTime, format } from 'date-fns-tz';
+
+export function formatDateTime(dt: Date, tz?: string): string {
+  return format(utcToZonedTime(dt, tz), 'MMM d, yyyy hh:mmaaa zzz', {
+    timeZone: tz || 'Etc/UTC',
+  });
+}

api/src/services/events/events.ts

@@ -1,6 +1,11 @@
-import type { QueryResolvers, MutationResolvers } from 'types/graphql';
+import type {
+  QueryResolvers,
+  MutationResolvers,
+  EventRelationResolvers,
+} from 'types/graphql';
 
 import { db } from 'src/lib/db';
+import { formatDateTime } from 'src/lib/formatters';
 
 export const events: QueryResolvers['events'] = () => {
   return db.event.findMany();
@@ -34,7 +39,25 @@ export const deleteEvent: MutationResolvers['deleteEvent'] = ({ id }) => {
   });
 };
 
-export const Event = {
+export const Event: EventRelationResolvers = {
+  formattedStartAt: (_obj, { root }) => {
+    return formatDateTime(root.startAt, root.timezone);
+  },
+  formattedEndAt: (_obj, { root }) => {
+    return formatDateTime(root.endAt, root.timezone);
+  },
+  formattedRegistrationStartAt: (_obj, { root }) => {
+    return formatDateTime(root.registrationStartAt, root.timezone);
+  },
+  formattedRegistrationEndAt: (_obj, { root }) => {
+    return formatDateTime(root.registrationEndAt, root.timezone);
+  },
+  formattedCreatedAt: (_obj, { root }) => {
+    return formatDateTime(root.createdAt, root.timezone);
+  },
+  formattedUpdatedAt: (_obj, { root }) => {
+    return formatDateTime(root.updatedAt, root.timezone);
+  },
   sessions: (_obj, { root }) => {
     return db.event.findUnique({ where: { id: root?.id } }).sessions();
   },