Logging

For logging use the Logger, exported by the logger module. It encapsulates a Winston logger. Its injection scope is transient, so you can set a context when you inject it.

For better privacy protection and searchability of logs, the logger cannot log arbitrary strings but only so called loggables. If you want to log something you have to use or create a loggable that implements the Loggable interface.

The message should be fixed in each loggable. If you want to log further data, put in the data field of the LogMessage, like in the example below.

export class YourLoggable implements Loggable {
    constructor(private readonly userId: EntityId) {}

    getLogMessage(): LogMessage {
        return {
            message: 'I am a log message.',
            data: { userId: this.userId, },
        };
    }
}

import { Logger } from '@src/core/logger';

export class YourUc {
    constructor(private logger: Logger) {
        this.logger.setContext(YourUc.name);
    }

    public sampleUcMethod(user) {
        this.logger.log(new YourLoggable(userId: user.id));
    }
}

This produces a logging output like

[NestWinston] Info - 2023-05-31 15:20:30.888   [YourUc] {  message: 'I am a log message.',  data: {   userId: '0000d231816abba584714c9e'  }}

Log levels and error logging

The logger exposes the methods log, warn, debug and verbose. It does not expose an error method because we don't want errors to be logged manually. All errors are logged in the exception filter.

Legacy logger

While transitioning to the new logger for loggables, the old logger for strings is still available as LegacyLogger.