Winston log format - json

Question

i am using Winston ^3.0.0-rc6 as below :
var options = {
file: {
level: 'info',
filename: `${appRoot}/logs/app.log`,
handleExceptions: true,
json: true,
prettyPrint: true,
maxsize: 5242880, // 5MB
maxFiles: 5,
colorize: true,
}
};
const jsonFormatter = (logEntry) => {
if (logEntry.type) {
const base = {
timestamp: new Date()
};
const json = Object.assign(base, logEntry);
logEntry[MESSAGE] = JSON.stringify(json);
} else {
logEntry = "";
}
return logEntry;
}
const logger = winston.createLogger({
format: winston.format(jsonFormatter)(),
transports: [
new winston.transports.File(options.file)
],
exceptionHandlers: [
new winston.transports.File(options.uncaughtExceptions)
]
});
my log output :
{"timestamp":"2018-06-10T07:41:03.387Z","type":"Authentication","status":"failed","level":"error","message":"Incorrect password"}
but i want them to be like :
{
"timestamp": "2018-06-10T07:41:03.387Z",
"type": "Authentication",
"status": "failed",
"level": "error",
"message": "Incorrect password"
}
i tried to play around with json : true , and prettyPrint but it did not do the trick .
Can any one help please
Thanks.

Answer 1

I noticed in your code that on the line
logEntry[MESSAGE] = JSON.stringify(json);
you're using JSON.stringify() which takes two more optional arguments
JSON.stringify(value[, replacer[, space]])
If you set space to the amount of spaces you'd like you'll get the output you're looking for. So change the initial line to be:
logEntry[MESSAGE] = JSON.stringify(json, null, 2); // or 4 ;)
(The replacer argument is null because we don't want to change the default behavior.)

Answer 2

This is deprecated: You can check the link here.
I tried to play around with json: true, and prettyPrint but it did not do the trick.
Simple code like this work for you:
const logger = winston.createLogger({
level: 'info',
format: winston.format.json(),
transports: [
//
// - Write to all logs with level `info` and below to `combined.log`
// - Write all logs error (and below) to `error.log`.
//
new winston.transports.File({ filename: 'error.log', level: 'error' }),
new winston.transports.File({ filename: 'combined.log' })
]
});
If this does not work, let me know so that I can improvise.