在nestjs中的过滤器内注入服务

Question

我正在尝试将nestjs-config注入到我创建的以下异常处理程序中：

import { ExceptionFilter, Catch, ArgumentsHost, Injectable } from '@nestjs/common';
import { HttpException } from '@nestjs/common';
import { InjectConfig } from 'nestjs-config';

@Injectable()
@Catch()
export class HttpExceptionFilter implements ExceptionFilter {
  constructor(
    @InjectConfig()
    private readonly config,
  ) {
    this.config = config.get('errors');
  }
  catch(exception: HttpException, host: ArgumentsHost) {
    // some code here that calls this.config
  }
}

但是它返回了未定义的：TypeError: Cannot read property 'get' of undefined

以下是异常处理程序的全局定义方式：

const app = await NestFactory.create(AppModule, { cors: true });
app.useGlobalFilters(new HttpExceptionFilter());
await app.listen(3000);

Answer 1

好的，我刚刚意识到，在你的代码中，你在容器之外创建了过滤器，因此ConfigService没有被注入。有几种方法可以解决这个问题。一

ConfigService.load(path.resolve(__dirname, 'config', '*.ts'))

const app = await NestFactory.create(AppModule, { cors: true });
app.useGlobalFilters(new HttpExceptionFilter(ConfigService));
await app.listen(3000);

或

const app = await NestFactory.create(AppModule, {cors: true});
const config = app.get<ConfigService>(ConfigService);
app.useGlobalFilters(new HttpExceptionFilter(config));
await app.listen(3000);

这取决于您的AppModule如下所示

@Module({
    imports: [ConfigModule.load(path.resolve(__dirname, 'config', '*.ts')],
})
export AppModule {}

或者像这样：

const app = await NestFactory.create(AppModule, {cors: true});
const httpExceptionFilter = app.get(HttpExpectionFilter);
app.useGlobalFilters(httpExpectionFilter);

Answer 2

通过调用ConfigService解决了这个问题，方法如下：

export class HttpExceptionFilter implements ExceptionFilter {

  constructor(private readonly config: ConfigService) {
    this.config = ConfigService.get('errors');
  }
  catch(exception: HttpException, host: ArgumentsHost) {
    // some code here that calls this.config
  }
}

Answer 3

对于Nestjs V8，您可以将其放在AppModule提供程序中：

{
  provide: APP_FILTER,
  useClass: HttpExceptionFilter,
},