Create a GraphQL subscription example

[ZenSoftware]

In progress...
Apollo Client connects and everything works, but this needs a publicly available example

• WebSocketLink connects and Nest @GqlGuard and @Roles decorators work with Subscriptions.
• Create an example

[ZenSoftware]

• Implemented client side GraphQL Subscription over WebSockets
• Implemented server side sample of a pub/sub Nest GraphQL Subscription service
• Works with the @Roles(roles: string | string[]) authorization to be used in conjunction with the JWT @UseGuards(GqlGuard) decorator.

zen/libs/main/src/lib/zen-portal/zen-super/zen-sample-subscription/zen-sample-subscription.component.ts

Lines 22 to 26 in 1019403

	constructor(private sampleSubscriptionGQL: SampleSubscriptionGQL) {
	this.#sub = this.sampleSubscriptionGQL.subscribe().subscribe(({ data }) => {
	this.recentValue = data?.sampleSubscription.message;
	});
	}

zen/apps/api/src/app/graphql/resolvers/Sample.ts

Lines 11 to 56 in 1019403

	export const typeDefs = gql`
	extend type Mutation {
	sampleUpload(file: Upload!): Boolean!
	}
	type SampleSubscriptionResult {
	message: String!
	}
	type Subscription {
	sampleSubscription: SampleSubscriptionResult!
	}
	`;
	const pubSub = new PubSub();
	interval(1000).subscribe(i =>
	pubSub.publish('sampleSubscription', {
	sampleSubscription: {
	message: `Server ticker ${i}`,
	},
	})
	);
	@Resolver()
	@UseGuards(GqlGuard)
	@Roles('Super')
	export class SampleResolver {
	@Mutation()
	async sampleUpload(@Args('file', { type: () => GraphQLUpload }) file: FileInfo) {
	const readStream = file.file.createReadStream();
	const chunks = [];
	for await (const chunk of readStream) {
	chunks.push(chunk);
	}
	const buffer = Buffer.concat(chunks);
	Logger.log(`Recieved '${file.file.filename}' ${buffer.byteLength} bytes`);
	return true;
	}
	@Subscription()
	async sampleSubscription(@GqlUser() user: RequestUser) {
	Logger.log(`sampleSubscription subscribed to by user with id ${user.id}`);
	return pubSub.asyncIterator('sampleSubscription');
	}
	}