Rocket.Chat/server/publications/room.js

const fields = {
	_id: 1,
	name: 1,
	fname: 1,
	t: 1,
	cl: 1,
	u: 1,
	// usernames: 1,
	topic: 1,
	announcement: 1,
	muted: 1,
	_updatedAt: 1,
	archived: 1,
	jitsiTimeout: 1,
	description: 1,
	default: 1,
	customFields: 1,

	// @TODO create an API to register this fields based on room type
	livechatData: 1,
	tags: 1,
	sms: 1,
	code: 1,
	joinCodeRequired: 1,
	open: 1,
	v: 1,
	label: 1,
	ro: 1,
	sentiment: 1
};


const roomMap = (record, fields) => {
	if (record._room) {
		return _.pick(record._room, ...Object.keys(fields));
	}
	console.log('Empty Room for Subscription', record);
	return {};
};

function getFieldsForUserId(userId) {
	if (RocketChat.authz.hasPermission(userId, 'view-join-code')) {
		return {
			...fields,
			joinCode: 1
		};
	}

	return fields;
}

Meteor.methods({
	'rooms/get'(updatedAt) {
		let options = {fields};

		if (!Meteor.userId()) {
			if (RocketChat.settings.get('Accounts_AllowAnonymousRead') === true) {
				return RocketChat.models.Rooms.findByDefaultAndTypes(true, ['c'], options).fetch();
			}
			return [];
		}

		this.unblock();

		options = {
			fields: getFieldsForUserId(this.userId)
		};

		if (updatedAt instanceof Date) {
			return {
				update: RocketChat.models.Rooms.findBySubscriptionUserIdUpdatedAfter(Meteor.userId(), updatedAt, options).fetch(),
				remove: RocketChat.models.Rooms.trashFindDeletedAfter(updatedAt, {}, {fields: {_id: 1, _deletedAt: 1}}).fetch()
			};
		}

		return RocketChat.models.Rooms.findBySubscriptionUserId(Meteor.userId(), options).fetch();
	},

	getRoomByTypeAndName(type, name) {
		if (!Meteor.userId() && RocketChat.settings.get('Accounts_AllowAnonymousRead') === false) {
			throw new Meteor.Error('error-invalid-user', 'Invalid user', { method: 'getRoomByTypeAndName' });
		}

		const roomFind = RocketChat.roomTypes.getRoomFind(type);

		let room;

		if (roomFind) {
			room = roomFind.call(this, name);
		} else {
			room = RocketChat.models.Rooms.findByTypeAndName(type, name).fetch();
		}

		if (!room) {
			throw new Meteor.Error('error-invalid-room', 'Invalid room', { method: 'getRoomByTypeAndName' });
		}

		if (!Meteor.call('canAccessRoom', room._id, Meteor.userId())) {
			throw new Meteor.Error('error-no-permission', 'No permission', { method: 'getRoomByTypeAndName' });
		}

		return roomMap({_room: room}, getFieldsForUserId(this.userId));
	}
});

RocketChat.models.Rooms.cache.on('sync', (type, room/*, diff*/) => {
	const records = RocketChat.models.Subscriptions.findByRoomId(room._id).fetch();
	for (const record of records) {
		RocketChat.Notifications.notifyUserInThisInstance(record.u._id, 'rooms-changed', type, roomMap({_room: room}, getFieldsForUserId(record.u._id)));
	}
});

RocketChat.models.Subscriptions.on('changed', (type, subscription/*, diff*/) => {
	if (type === 'inserted' || type === 'removed') {
		const room = RocketChat.models.Rooms.findOneById(subscription.rid);
		if (room) {
			RocketChat.Notifications.notifyUserInThisInstance(subscription.u._id, 'rooms-changed', type, roomMap({_room: room}, getFieldsForUserId(subscription.u._id)));
		}
	}
});