What is the correct way to create a winston logger in TypeScript that will log the express Morgan middleware logging? I found a number of JavaScript samples but have had trouble converting them over to TypeScript, because I get an error Type '{ write: (message: string, encoding: any) => {}; logger: any; }' is not assignable to type '(options?: any) => ReadableStream'. Object literal may only specify known properties, and 'write' does not exist in type '(options?: any) => ReadableStream'.
Here is my code:
import { Logger, transports } from 'winston';
// http://tostring.it/2014/06/23/advanced-logging-with-nodejs/
// https://www.loggly.com/ultimate-guide/node-logging-basics/
const logger = new Logger({
transports: [
new (transports.Console)({
level: process.env.NODE_ENV === 'production' ? 'error' : 'debug',
handleExceptions: true,
json: false,
colorize: true
}),
new (transports.File)({
filename: 'debug.log', level: 'info',
handleExceptions: true,
json: true,
colorize: false
})
],
exitOnError: false,
});
if (process.env.NODE_ENV !== 'production') {
logger.debug('Logging initialized at debug level');
}
// [ts]
// Type '{ write: (message: string, encoding: any) => {}; logger: any; }' is not assignable to type '(options?: any) => ReadableStream'.
// Object literal may only specify known properties, and 'write' does not exist in type '(options?: any) => ReadableStream'.
logger.stream = {
write: function (message: string, encoding: any) {
logger.info(message);
};
}
export default logger;
I have been able to work around this by adjusting my code to use const winston = require('winston');
but would like to know how you are supposed to do this maintaining types?
Ultimately I ended up with this as a solution. I created a class with one method called write
export class LoggerStream {
write(message: string) {
logger.info(message.substring(0, message.lastIndexOf('\n')));
}
}
then when adding to express I created an instance of the class:
app.use(morgan('combined', { stream: new LoggerStream() }));
This works well for my situation