NestJS in conjunction with Axios - axios

Question

I have a NestJS application that acts as a BFF (Backend for Frontend) which exposes a certain endpoint. That endpoint uses Axios to send multiple requests to my backend. Some of these requests to the backend can return different status codes, which I want to propagate back to the caller. However, I don't want to catch every request manually. Currently, it throws 500 if any Axios request fails in the pipeline.
I thought about implementing a global exception filter for Axios exceptions, that will check the returned status code from Axios and throw an appropriate HttpException exception that NestJS will catch (e.g. if any Axios request failed and returned 401, throw an UnauthorizedException which NestJS will catch and return back to the client, instead of 500).
Is it a possible approach, or is there anything else I can do?

Answer 1

If you want, you can use Exception filters
So first you need to create a file for the exception filter.
// axios.exception-filter.ts
import { ArgumentsHost, Catch, ExceptionFilter } from '#nestjs/common';
import { Request, Response } from 'express';
import { AxiosError } from 'axios';
#Catch(AxiosError)
export class HttpExceptionFilter implements ExceptionFilter {
catch(exception: AxiosError, host: ArgumentsHost) {
const ctx = host.switchToHttp();
const response = ctx.getResponse<Response>();
const request = ctx.getRequest<Request>();
console.log(exception);
response.status(400).json({
statusCode: 400,
timestamp: new Date().toISOString(),
path: request.url,
});
}
}
And in your main.ts add this
app.useGlobalFilters(new HttpExceptionFilter());
And now in response.status(400).json({}) you can add everything you want in your body. Like the error message of Axios.