Exception filters

To access the I18nContext inside your exception filters use the I18nContext.current() helper function.

src/test.filter.ts

import { ArgumentsHost, Catch, ExceptionFilter, HttpException } from "@nestjs/common";
import { I18nContext } from "nestjs-i18n";

@Catch()
export class TestExceptionFilter implements ExceptionFilter {
  catch(exception: HttpException, host: ArgumentsHost) {
    const i18n = I18nContext.current<I18nTranslations>(host);
    const response = host.switchToHttp().getResponse<any>();

    console.log('current language', i18n.lang);

    response
      .status(500)
      .send(`Your language is: ${i18n.lang}`);
  }
}

caution

When using http or graphql nestjs-i18n uses middleware to make things work. However when throwing exceptions in middleware this can lead to throwing your exception before the nestjs-i18n middleware had been reached. To solve this problem you'll need to register the I18nMiddleware globally.

src/main.ts

import { NestFactory } from '@nestjs/core';
import { AppModule } from './app.module';
import { I18nMiddleware } from 'nestjs-i18n';

async function bootstrap() {
  const app = await NestFactory.create(AppModule);
  app.use(I18nMiddleware);
  await app.listen(3000);
}
bootstrap();

or

src/app.module.ts

import { MiddlewareConsumer, Module, NestModule } from '@nestjs/common';
import { I18nMiddleware } from 'nestjs-i18n';

@Module({
  ...
})
export class AppModule implements NestModule {
  configure(consumer: MiddlewareConsumer) {
    consumer.apply(I18nMiddleware, MyMiddleware).forRoutes('*');
  }
}