Nestjs Configcat

app.controller.ts

import { ConfigCatClient } from 'configcat-common/lib/ConfigCatClient';

@Controller('travel')
export class AppController {
  constructor(
    private readonly appService: AppService,
    private readonly flags: ConfigCatClient
  ) {}

  @Get('mileage')
  async getMileageFeature(): Promise<Boolean> {
    // Create a variable to store the state of the feature flag from ConfigCat.
    // This variable will be automatically updated every 60 seconds by default.
    const canShowMileageFeature = await this.flags.getValueAsync("canshowmileagefeature", false)

    if (canShowMileageFeature) {
      // When true is returned to the frontend, the Gas Mileage feature is rendered
      return true
    } else {
      // When false is returned to the frontend, the Gas Mileage feature is not rendered. Instead, the subscription form will be rendered.
      return false
    }
  }
}

configcat.module.ts

import { Global, Module, OnModuleDestroy } from '@nestjs/common';
import { ConfigCatClient } from 'configcat-common/lib/ConfigCatClient';
import * as ConfigCat from 'configcat-node';

const configCatClient = {
  provide: ConfigCatClient,
  useFactory: () => {
    // or any other method to get the key
    const key = process.env.CONFIG_CAT_SDK_KEY;
    return ConfigCat.createClient(key);
  },
};

@Global()
@Module({ providers: [configCatClient], exports: [configCatClient] })
export class ConfigCatModule implements OnModuleDestroy {
  constructor(private readonly flags: ConfigCatClient) {}

  async onModuleDestroy(): Promise<void> {
    this.flags.dispose();
  }
}