I have a code written in node-nats-streaming and trying to convert it to newer jetstream. A part of code looks like this:
import { Message, Stan } from 'node-nats-streaming';
import { Subjects } from './subjects';
interface Event {
subject: Subjects;
data: any;
}
export abstract class Listener<T extends Event> {
abstract subject: T['subject'];
abstract queueGroupName: string;
abstract onMessage(data: T['data'], msg: Message): void;
private client: Stan;
protected ackWait = 5 * 1000;
constructor(client: Stan) {
this.client = client;
}
subscriptionOptions() {
return this.client
.subscriptionOptions()
.setDeliverAllAvailable()
.setManualAckMode(true)
.setAckWait(this.ackWait)
.setDurableName(this.queueGroupName);
}
listen() {
const subscription = this.client.subscribe(
this.subject,
this.queueGroupName,
this.subscriptionOptions()
);
subscription.on('message', (msg: Message) => {
console.log(`Message received: ${this.subject} / ${this.queueGroupName}`);
const parsedData = this.parseMessage(msg);
this.onMessage(parsedData, msg);
});
}
parseMessage(msg: Message) {
const data = msg.getData();
return typeof data === 'string'
? JSON.parse(data)
: JSON.parse(data.toString('utf8'));
}
}
As I searched through the documents it seems I can do something like following:
import { connect } from "nats";
const jsm = await nc.jetstreamManager();
const cfg = {
name: "EVENTS",
subjects: ["events.>"],
};
await jsm.streams.add(cfg);
But it seems there are only name and subject options available. But from my original code I need a data property it can handle JSON objects. Is there a way I can convert this code to a Jetstream code or I should change the logic of the whole application as well?
Related
Let's say we have a bookshop and an author entity, to show the author their earnings stat, we want to check if the authenticated user is indeed the author themselves. So we have:
#UseGuards(GqlAuthGuard)
#ResolveField(() => [Eearning], { name: 'earnings' })
async getEarnings(
#Parent() author: Author,
#GqlUser() user: User,
) {
if (user.id !== author.id)
throw new UnauthorizedException(
'Each author can only view their own data',
);
// rest of the function implementation
}
We could query this:
query {
author(id: "2bd79-6d7f-76a332b06b") {
earnings {
sells
}
}
}
Now imagine we want to use a custom Guard instead of that if statement. Something like below:
#Injectable()
export class AutherGuard implements CanActivate {
canActivate(context: ExecutionContext): boolean {
const ctx = GqlExecutionContext.create(context);
// const artistId = ?
}
}
How can I access the id argument given to the author query when AutherGuard is used for the getEarnings handler?
Not sure how documented is that but the parent object can be accessed through the getRoot method:
const gqlContext = GqlExecutionContext.create(context);
const root = gqlContext.getRoot();
const authorId = root.id;
In fact, we have a helper function that we use like this:
export function getArgs(context: ExecutionContext): any {
if (context.getType<GqlContextType>() === "graphql") {
const gqlContext = GqlExecutionContext.create(context);
return { ...gqlContext.getArgs(), $parent: gqlContext.getRoot() };
} else if (context.getType() === "http") {
return context.switchToHttp().getRequest().params;
}
}
...
const args = getArgs(context);
const authorId = _.get(args, "$parent.id");
I have this code to change the default message from typeorm when a value in a unique column already exists. It just creates a custom message when we get an error 23505.
if (error.code === '23505') {
// message = This COLUMN VALUE already exists.
const message = error.detail.replace(
/^Key \((.*)\)=\((.*)\) (.*)/,
'The $1 $2 already exists.',
);
throw new BadRequestException(message);
}
throw new InternalServerErrorException();
I will have to use it in other services, so I would like to abstract that code.
I think I could just create a helper and then I import and call it wherever I need it. But I don’t know if there is a better solution to use it globally with a filter or an interceptor, so I don’t have to even import and call it in different services.
Is this possible? how can that be done?
If it is not possible, what do you think the best solution would be?
Here all the service code:
#Injectable()
export class MerchantsService {
constructor(
#InjectRepository(Merchant)
private merchantRepository: Repository<Merchant>,
) {}
public async create(createMerchantDto: CreateMerchantDto) {
try {
const user = this.merchantRepository.create({
...createMerchantDto,
documentType: DocumentType.NIT,
isActive: false,
});
await this.merchantRepository.save(user);
const { password, ...merchantData } = createMerchantDto;
return {
...merchantData,
};
} catch (error) {
if (error.code === '23505') {
// message = This COLUMN VALUE already exists.
const message = error.detail.replace(
/^Key \((.*)\)=\((.*)\) (.*)/,
'The $1 $2 already exists.',
);
throw new BadRequestException(message);
}
throw new InternalServerErrorException();
}
}
public async findOneByEmail(email: string): Promise<Merchant | null> {
return this.merchantRepository.findOneBy({ email });
}
}
I created an exception filter for typeORM errors.
This was the result:
import {
ArgumentsHost,
Catch,
ExceptionFilter,
HttpStatus,
InternalServerErrorException,
} from '#nestjs/common';
import { Response } from 'express';
import { QueryFailedError, TypeORMError } from 'typeorm';
type ExceptionResponse = {
statusCode: number;
message: string;
};
#Catch(TypeORMError, QueryFailedError)
export class TypeORMExceptionFilter implements ExceptionFilter {
private defaultExceptionResponse: ExceptionResponse =
new InternalServerErrorException().getResponse() as ExceptionResponse;
private exceptionResponse: ExceptionResponse = this.defaultExceptionResponse;
catch(exception: TypeORMError | QueryFailedError, host: ArgumentsHost) {
const ctx = host.switchToHttp();
const response = ctx.getResponse<Response>();
exception instanceof QueryFailedError &&
this.setQueryFailedErrorResponse(exception);
response
.status(this.exceptionResponse.statusCode)
.json(this.exceptionResponse);
}
private setQueryFailedErrorResponse(exception: QueryFailedError): void {
const error = exception.driverError;
if (error.code === '23505') {
const message = error.detail.replace(
/^Key \((.*)\)=\((.*)\) (.*)/,
'The $1 $2 already exists.',
);
this.exceptionResponse = {
statusCode: HttpStatus.BAD_REQUEST,
message,
};
}
// Other error codes can be handled here
}
// Add more methods here to set a different response for any other typeORM error, if needed.
// All typeORM erros: https://github.com/typeorm/typeorm/tree/master/src/error
}
I set it globally:
import { TypeORMExceptionFilter } from './common';
async function bootstrap() {
//...Other code
app.useGlobalFilters(new TypeORMExceptionFilter());
//...Other code
await app.listen(3000);
}
bootstrap();
And now I don't have to add any code when doing changes in the database:
#Injectable()
export class MerchantsService {
constructor(
#InjectRepository(Merchant)
private merchantRepository: Repository<Merchant>,
) {}
public async create(createMerchantDto: CreateMerchantDto) {
const user = this.merchantRepository.create({
...createMerchantDto,
documentType: DocumentType.NIT,
isActive: false,
});
await this.merchantRepository.save(user);
const { password, ...merchantData } = createMerchantDto;
return {
...merchantData,
};
}
}
Notice that now I don't use try catch because nest is handling the exceptions. When the repository save() method returns an error (actually it is a rejected promise), it is caught in the filter.
I tried the sample SSE application provided with nest.js (28-SSE), and modified the sse endpoint to send a counter:
#Sse('sse')
sse(): Observable<MessageEvent> {
return interval(5000).pipe(
map((_) => ({ data: { hello: `world - ${this.c++}` }} as MessageEvent)),
);
}
I expect that each client that is listening to this SSE will receive the message, but when opening multiple browser tabs I can see that each message is consumed only by one browser, so if I have three browsers open I get the following:
How can I get the expected behavior?
To achieve the behavior you're expecting you need to create a separate stream for each connection and push the data stream as you wish.
One possible minimalistic solution is below
import { Controller, Get, MessageEvent, OnModuleDestroy, OnModuleInit, Res, Sse } from '#nestjs/common';
import { readFileSync } from 'fs';
import { join } from 'path';
import { Observable, ReplaySubject } from 'rxjs';
import { map } from 'rxjs/operators';
import { Response } from 'express';
#Controller()
export class AppController implements OnModuleInit, OnModuleDestroy {
private stream: {
id: string;
subject: ReplaySubject<unknown>;
observer: Observable<unknown>;
}[] = [];
private timer: NodeJS.Timeout;
private id = 0;
public onModuleInit(): void {
this.timer = setInterval(() => {
this.id += 1;
this.stream.forEach(({ subject }) => subject.next(this.id));
}, 1000);
}
public onModuleDestroy(): void {
clearInterval(this.timer);
}
#Get()
public index(): string {
return readFileSync(join(__dirname, 'index.html'), 'utf-8').toString();
}
#Sse('sse')
public sse(#Res() response: Response): Observable<MessageEvent> {
const id = AppController.genStreamId();
// Clean up the stream when the client disconnects
response.on('close', () => this.removeStream(id));
// Create a new stream
const subject = new ReplaySubject();
const observer = subject.asObservable();
this.addStream(subject, observer, id);
return observer.pipe(map((data) => ({
id: `my-stream-id:${id}`,
data: `Hello world ${data}`,
event: 'my-event-name',
}) as MessageEvent));
}
private addStream(subject: ReplaySubject<unknown>, observer: Observable<unknown>, id: string): void {
this.stream.push({
id,
subject,
observer,
});
}
private removeStream(id: string): void {
this.stream = this.stream.filter(stream => stream.id !== id);
}
private static genStreamId(): string {
return Math.random().toString(36).substring(2, 15);
}
}
You can make a separate service for it and make it cleaner and push stream data from different places but as an example showcase this would result as shown in the screenshot below
This behaviour is correct. Each SSE connection is a dedicated socket and handled by a dedicated server process. So each client can receive different data.
It is not a broadcast-same-thing-to-many technology.
How can I get the expected behavior?
Have a central record (e.g. in an SQL DB) of the desired value you want to send out to all the connected clients.
Then have each of the SSE server processes watch or poll that central record
and send out an event each time it changes.
you just have to generate a new observable for each sse connection of the same subject
private events: Subject<MessageEvent> = new Subject();
constuctor(){
timer(0, 1000).pipe(takeUntil(this.destroy)).subscribe(async (index: any)=>{
let event: MessageEvent = {
id: index,
type: 'test',
retry: 30000,
data: {index: index}
} as MessageEvent;
this.events.next(event);
});
}
#Sse('sse')
public sse(): Observable<MessageEvent> {
return this.events.asObservable();
}
Note: I'm skipping the rest of the controller code.
Regards,
I have this:
LocationController.ts
import {GenericController} from './_genericController';
interface Response {
id : number,
code: string,
name: string,
type: string,
long: number,
lat: number
}
const fields = ['code','name','type','long','lat'];
class LocationController extends GenericController{
tableName:string = 'location';
fields:Array<any> = fields;
}
const locationController = new LocationController();
const get = async (req, res) => {
await locationController._get(req, res);
}
export {get};
GenericController.ts
interface Response {
id : number
}
export class GenericController{
tableName:string = '';
fields:Array<any> = [];
_get = async (req, res) => {
try{
const id = req.body['id'];
const send = async () => {
const resp : Array<Response> = await db(this.tableName).select(this.fields).where('id', id)
if (resp[0] === undefined) {
// some error handling
}
res.status(status.success).json(resp[0]);
}
await send();
}catch (error){
// some error handling
}
}
}
What I want to do is to pass the Response interface from LocationController to the GenericController parent, so that the response is typed accurately depending on how the child class has defined it. Clearly it doesn't work like this since the interface is defined outside of the class so the parent has no idea about the Response interface in the LocationController.ts file.
I've tried passing interface as an argument in the constructor, that doesn't work. So is there a way I can make this happen? I feel like I'm missing something really simple.
Typically, generics are used in a situation like this. Here's how I'd do it:
interface Response {
id: number;
}
// Note the generic parameter <R extends Response>
export class GenericController<R extends Response> {
tableName: string = "";
fields: Array<any> = [];
_get = async (req, res) => {
try {
const id = req.body["id"];
const send = async () => {
// The array is now properly typed. You don't know the exact type,
// but you do know the constraint - R is some type of `Response`
let resp: Array<R> = await db(this.tableName).select(this.fields).where("id", id);
if (resp[0] === undefined) {
// some error handling
}
res.status(status.success).json(resp[0]);
};
await send();
} catch (error) {
// some error handling
}
};
}
import { GenericController } from "./_genericController";
interface Response {
id: number;
code: string;
name: string;
type: string;
long: number;
lat: number;
}
const fields = ["code", "name", "type", "long", "lat"];
// Here we tell the GenericController exactly what type of Response it's going to get
class LocationController extends GenericController<Response> {
tableName: string = "location";
fields: Array<any> = fields;
}
const locationController = new LocationController();
const get = async (req, res) => {
await locationController._get(req, res);
};
export { get };
If this is not enough and you wish to somehow know the exact response type you're going to get, I believe the only way is a manual check. For example:
import { LocationResponse } from './locationController';
// ... stuff
// Manual runtime type check
if (this.tableName === 'location') {
// Manual cast
resp = resp as Array<LocationResponse>
}
// ...
You could also check the form of resp[0] (if (resp[0].hasOwnProperty('code')) { ... }) and cast accordingly. There are also nicer ways to write this, but the basic idea remains the same.
Generally, a properly written class should be unaware of any classes that inherit from it. Putting child-class-specific logic into your generic controller is a code smell. Though as always, it all depends on a particular situation.
I'm just getting into Fastify with Typescript and really enjoying it.
However, I'm trying to figure out if I can type the response payload. I have the response schema for serialization working and that may be sufficient, but I have internally typed objects (such as IUser) that it would be nice to have Typescript check against.
The following works great, but I'd like to return an TUser for example and have typescript if I return something different. Using schema merely discludes fields.
interface IUser {
firstname: string,
lastname: string
} // Not in use in example
interface IUserRequest extends RequestGenericInterface {
Params: { username: string };
}
const getUserHandler = async (
req: FastifyRequest<IUserRequest, RawServerBase, IncomingMessage | Http2ServerRequest>
) => {
const { username } = req.params;
return { ... }; // Would like to return instance of IUser
};
app.get<IUserRequest>('/:username', { schema }, helloWorldHandler);
Is there an equivalent of RequestGenericInterface I can extend for the response?
Small Update: It seems that the reply.send() can be used to add the type, but it would be nice for self-documentation sake to provide T higher up.
From the documentation:
Using the two interfaces, define a new API route and pass them as generics. The shorthand route methods (i.e. .get) accept a generic object RouteGenericInterface containing five named properties: Body, Querystring, Params, Headers and Reply.
You can use the Reply type.
interface MiscIPAddressRes {
ipv4: string
}
server.get<{
Reply: MiscIPAddressRes
}>('/misc/ip-address', async (req, res) => {
res
.status(_200_OKAY)
.send({
ipv4: req.ip // this will be typechecked
})
})
After looking at the type definitions, I found out that there is also an alternative way to only type-check the handler (like in Julien TASSIN's answer), like this:
import { FastifyReply, FastifyRequest, RawReplyDefaultExpression, RawRequestDefaultExpression, RawServerDefault } from "fastify";
import { RouteGenericInterface } from "fastify/types/route";
interface IUser {
firstname: string;
lastname: string;
}
interface IUserRequest extends RouteGenericInterface {
Params: { username: string };
Reply: IUser; // put the response payload interface here
}
function getUserHandler(
request: FastifyRequest<IUserRequest>,
reply: FastifyReply<
RawServerDefault,
RawRequestDefaultExpression,
RawReplyDefaultExpression,
IUserRequest // put the request interface here
>
) {
const { username } = request.params;
// do something
// the send() parameter is now type-checked
return reply.send({
firstname: "James",
lastname: "Bond",
});
}
You can also create your own interface with generic to save writing repeating lines, like this:
import { FastifyReply, FastifyRequest, RawReplyDefaultExpression, RawRequestDefaultExpression, RawServerDefault } from "fastify";
import { RouteGenericInterface } from "fastify/types/route";
export interface FastifyReplyWithPayload<Payload extends RouteGenericInterface>
extends FastifyReply<
RawServerDefault,
RawRequestDefaultExpression,
RawReplyDefaultExpression,
Payload
> {}
then use the interface like this:
function getUserHandler(
request: FastifyRequest<IUserRequest>,
reply: FastifyReplyWithPayload<IUserRequest>
) {
const { username } = request.params;
// do something
// the send() parameter is also type-checked like above
return reply.send({
firstname: "James",
lastname: "Bond",
});
}
If you want to type the handler only, you can perform it this way
import { RawReplyDefaultExpression, RawRequestDefaultExpression, RawServerDefault, RouteHandler, RouteHandlerMethod } from "fastify";
const getUserHandler: RouteHandlerMethod<
RawServerDefault,
RawRequestDefaultExpression,
RawReplyDefaultExpression,
{ Reply: IUser; Params: { username: string } }
> = async (
req: FastifyRequest<IUserRequest, RawServerBase, IncomingMessage | Http2ServerRequest>
) => {
const { username } = req.params;
return { ... }; // Would like to return instance of IUser
};
Trying to type these was a truely awful experience. Thanks to the other answers, this is where I ended up. Bit of a code dump to make life easier for others.
request-types.ts
With this I am standardising my response to optionally have data and message.
import {
FastifyReply,
FastifyRequest,
RawReplyDefaultExpression,
RawRequestDefaultExpression,
RawServerDefault,
} from 'fastify';
type ById = {
id: string;
};
type ApiRequest<Body = void, Params = void, Reply = void> = {
Body: Body;
Params: Params;
Reply: { data?: Reply & ById; message?: string };
};
type ApiResponse<Body = void, Params = void, Reply = {}> = FastifyReply<
RawServerDefault,
RawRequestDefaultExpression,
RawReplyDefaultExpression,
ApiRequest<Body, Params, Reply>
>;
type RouteHandlerMethod<Body = void, Params = void, Reply = void> = (
request: FastifyRequest<ApiRequest<Body, Params, Reply>>,
response: ApiResponse<Body, Params, Reply>
) => void;
export type DeleteRequestHandler<ReplyPayload = ById> = RouteHandlerMethod<void, ById, ReplyPayload>;
export type GetRequestHandler<ReplyPayload> = RouteHandlerMethod<void, ById, ReplyPayload>;
export type PostRequestHandler<Payload, ReplyPayload> = RouteHandlerMethod<Payload, void, ReplyPayload>;
export type PatchRequestHandler<Payload, ReplyPayload> = RouteHandlerMethod<Payload, ById, ReplyPayload>;
export type PutRequestHandler<Payload, ReplyPayload> = RouteHandlerMethod<Payload, ById, ReplyPayload>;
Usage
get-account.ts - GetRequestHandler
export const getAccount: GetRequestHandler<AccountResponseDto> = async (request, reply) => {
const { id } = request.params;
...
const account = await Account.findOne....
...
if (account) {
return reply.status(200).send({ data: account });
}
return reply.status(404).send({ message: 'Account not found' });
};
delete-entity.ts - DeleteRequestHandler
export const deleteEntity: DeleteRequestHandler = async (request, reply) => {
const { id } = request.params;
...
// Indicate success by 200 and returning the id of the deleted entity
return reply.status(200).send({ data: { id } });
};
update-account.ts - PatchRequestHandler
export const updateAccount: PatchRequestHandler<
UpdateAccountRequestDto,
AccountResponseDto
> = async (request, reply) => {
const { id } = request.params;
...
return reply.status(200).send({ data: account });
};
register-account-routes.ts - No errors with provided handler.
export const registerAccountRoutes = (app: FastifyInstance) => {
app.get(EndPoints.ACCOUNT_BY_ID, getAccount);
app.patch(EndPoints.ACCOUNT_BY_ID, updateAccount);
app.post(EndPoints.ACCOUNTS_AUTHENTICATE, authenticate);
app.put(EndPoints.ACCOUNTS, createAccount);
};