How to get response body in format function

[hotrush]

Can i get response body inside format function to log it?

[rosston]

Given that the format function is being called by the internals of winston (not express-winston) and that we call log on the winston instance only once all the log meta has been put together, I believe you should be able to just use info.meta.res to get at the response object in your format function.

You may also need to add body to your responseWhitelist (and perhaps add a responseFilter if you're worried about logging sensitive information).

[hotrush]

Hi @rosston Problem is that i tried to add body into response whitelist (responseWhitelist: [...expressWinston.responseWhitelist, 'body']), but info.meta.res still contains only { statusCode: 200 }

[rosston]

Hm, @hotrush, I'm unable to replicate the issue you're seeing. Here's my code:

const express = require('express');
const winston = require('winston');
const expressWinston = require('express-winston');

const app = express();

app.use(expressWinston.logger({
  transports: [
    new winston.transports.Console()
  ],
  format: winston.format.combine(
    winston.format.timestamp(),
    winston.format.printf((info) => {
      console.log('res', info.meta.res);
      return `${info.meta.res.body}`;
    })
  ),
  responseWhitelist: [...expressWinston.responseWhitelist, 'body']
}));

app.use('/', (req, res, next) => {
  res.status(200).send('this is the response body');
});

app.listen('9999');

console.log('listening on 9999');

When it runs, I get the following output:

res { statusCode: 200, body: 'this is the response body' }
this is the response body

[rosston]

I'm going to close this for now since I don't think the problem is within express-winston. If you feel it still needs attention from someone working on express-winston, feel free to comment here.

[nowycondro]

It only works if the body is a string, doesn't work with json.