Meta is null in Winston-mongodb - node.js

Question

I am using winston-mongodb modlue to log the request response.
Logger.service.ts
const options = {
console: {
db: DB_URL,
level: 'info',
format: format.combine(format.timestamp(), format.json()),
collection: 'logs',
},
error: {
db: DB_URL,
level: 'error',
format: format.combine(format.timestamp(), format.json()),
collection: 'logs',
}
};
const logger = createLogger({
transports: [
new MongoDB(options.console),
new MongoDB(options.error)
],
});
Server.ts
server.listen(port, () => {
logger.info({message:`Server is up and running on port ${port}`, meta: {
myProp: 'foo'
}});
);
Result:
{
"_id" : ObjectId("5ed8bd2c726d273004b082ca"),
"timestamp" : ISODate("2020-06-04T09:21:48.835Z"),
"level" : "info",
"message" : "Server is up and running on port 4000 HI",
**"meta" : null**
}
I am trying to add meta data to logger. But it is adding null to the result.

Answer 1

To get err object stored in the meta (with all its javascript properties), you need to specify :
format.metadata()
In the createLogger call.
Here is a working sample code:
// Declare winston
const winston = require("winston");
// Import all needed using Object Destructuring
const { createLogger, format, transports } = require("winston");
const { combine, timestamp, printf } = format;
// Export the module
module.exports = function (err, req, res, next) {
const logger = createLogger({
level: "error",
format: combine(
format.errors({ stack: true }), // log the full stack
timestamp(), // get the time stamp part of the full log message
printf(({ level, message, timestamp, stack }) => {
// formating the log outcome to show/store
return `${timestamp} ${level}: ${message} - ${stack}`;
}),
format.metadata() // >>>> ADD THIS LINE TO STORE the ERR OBJECT IN META field
),
transports: [
new transports.Console(), // show the full stack error on the console
new winston.transports.File({
// log full stack error on the file
filename: "logfile.log",
format: format.combine(
format.colorize({
all: false,
})
),
}),
new winston.transports.MongoDB({
db: "mongodb://localhost/logdb",
// collection: "log",
level: "error",
storeHost: true,
capped: true,
// metaKey: 'meta'
}),
],
});
logger.log({
level: "error",
message: err,
});
// Response sent to client but nothing related to winston
res.status(500).json(err.message);
};

Answer 2

try this
// create new meta object to store in database
let logMeta={
stack: err.stack, // error stack
otherInfo: otherInfoData // any other info you want to store
}
// use metadata propery for meta
logger.error(err.message, {metadata: logMeta });

Answer 3

OR another way, if you are exporting the function as error middleware (using nodejs, express):
module.exports = function (err, req, res, next) {
logger.log({
level: "error",
message: err.message,
stack: err.stack,
metadata: err.stack, // Put what you like as meta
});
res.status(500).send("Uncaught error caught here.");
};

Answer 4

Specify metadata object explicitly:
logger.error(err.message, {metadata: err.stack});

Answer 5

apparently i had the same problem where the meta property in mongoDB transport was null: This is how i fixed it....
const winston = require("winston")
const { format } = require("winstone")
winstone.add(new
winstone.transports.MongoDB({
format:format.metadata()})