How to set dynamic point and prefix in service nestjs ?

[supryantowp]

I'm working on a NestJS application that uses rate-limiter-flexible for rate limiting. I want to update the rate limiter's settings, specifically the points and keyPrefix properties, based on dynamic values obtained from a configuration object (throttle.limit and channel). How can I correctly implement this dynamic update in my code to achieve the desired rate limiting behavior?

keyPrefix: string;
  points: number;

  constructor(
    private readonly prisma: PrismaService,
    private readonly schedulerRegistry: SchedulerRegistry,
  ) {
    this.points = 0;
    this.keyPrefix = '';

    this.limiter = new RateLimiterMemory({
      keyPrefix: this.keyPrefix, // Use the keyPrefix property
      points: this.points, // Set the initial points as per your configuration
      duration: 60, // Set the duration as per your configuration
    });
  }
  
  async checkChannelThrottle(channel: string) {
    const config = await this.prisma.timeFrequency.findFirst({
      where: { id: 2 },
      select: { time: true },
    });

    const throttle = Object.values(config?.time || []).find(
      (val) => val.channel.toLowerCase() === channel,
    );

    if (throttle) {
      this.keyPrefix = channel;
      this.points = throttle.limit;
     
      try {
        const { remainingPoints } = await this.limiter.consume(channel, 1);

        console.log('Request accepted.');
        console.log(`Remaining points: ${remainingPoints}`);
      } catch (reason) {
        console.log('Request rejected. Reason:', reason);
        // Handle the rate limiting rejection here
      }
    } else {
      console.log('Channel throttle configuration not found.');
      // Handle the case when throttle configuration is not found
    }
  }

[supryantowp]

it works but this is the correct way to solve problem ?

private rateLimits: Map<string, RateLimiterMemory> = new Map();

let rateLimiter = this.rateLimits.get(keyPrefix);

  if (!rateLimiter) {
        rateLimiter = new RateLimiterMemory({
          keyPrefix,
          points,
          duration: 60, // Set the duration as per your configuration
        });

        this.rateLimits.set(keyPrefix, rateLimiter);
      }

[animir]

Hi @supryantowp
This question is more about what you exactly need. It is fair not only for NestJS.

If you don't need to keep previously consumed points they will be reset after this call this.rateLimits.set(keyPrefix, rateLimiter).
If you need to keep consumed points you can change points of already created limiter on the fly. Just call ateLimiter.points = points.
I hope this answers your question.