Logging with Winston or Pino in NestJS - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the Winston logger in a NestJS service.

NestJS

import { Logger } from '[1]';

Drag options to blanks, or click blank then click option'

Apino

Bexpress

Cnestjs/common

Dwinston

Attempts:

3 left

💡 Hint

Common Mistakes

Importing from 'nestjs/common' instead of 'winston'.

Confusing Winston with Pino or Express.

Winston is imported from the 'winston' package to use its logging features.

2fill in blank

medium

Complete the code to create a Winston logger instance with console transport.

NestJS

const logger = winston.createLogger({ transports: [new winston.transports.[1]()] });

Drag options to blanks, or click blank then click option'

AFile

BHttp

CConsole

DStream

Attempts:

3 left

💡 Hint

Common Mistakes

Using File transport when console output is needed.

Using Http or Stream transports incorrectly.

The Console transport outputs logs to the console, which is common for development.

3fill in blank

hard

Fix the error in the NestJS logger injection code.

NestJS

constructor(private readonly logger: [1]) {}

Drag options to blanks, or click blank then click option'

ALogger

BConsoleLogger

CWinstonLogger

DLoggerService

Attempts:

3 left

💡 Hint

Common Mistakes

Using LoggerService instead of Logger class.

Using WinstonLogger which is not a NestJS injectable class.

In NestJS, the Logger class is used for logging and can be injected as a service.

4fill in blank

hard

Fill both blanks to configure Pino logger with pretty print and level 'debug'.

NestJS

const logger = pino({ level: '[1]', transport: { target: '[2]' } });

Drag options to blanks, or click blank then click option'

Adebug

Binfo

Cpino-pretty

Dpino-http

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'info' level instead of 'debug' for detailed logs.

Using 'pino-http' which is for HTTP logging middleware.

The level 'debug' enables detailed logs. The 'pino-pretty' target formats logs nicely for console.

5fill in blank

hard

Fill all three blanks to create a Winston logger with JSON format, timestamp, and console transport.

NestJS

const logger = winston.createLogger({ format: winston.format.combine(winston.format.[2](), winston.format.[1]()), transports: [new winston.transports.[3]()] });

Drag options to blanks, or click blank then click option'

Ajson

Btimestamp

CConsole

Dcolorize

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'colorize' instead of 'json' for format.

Using 'File' transport instead of 'Console' for terminal output.

Combining json format with timestamp adds time info to logs. Console transport outputs logs to terminal.

Practice

1.

What is the main purpose of using Winston or Pino in a NestJS application?

easy

A. To handle HTTP requests and responses

B. To log application events and errors for monitoring and debugging

C. To manage database connections efficiently

D. To compile TypeScript code into JavaScript

Solution

1. Step 1: Understand logging role

   Logging tools like Winston or Pino record app events and errors to help developers monitor and debug the app.

2. Step 2: Identify unrelated options

   Database management, HTTP handling, and code compilation are unrelated to logging.

3. Final Answer:

   To log application events and errors for monitoring and debugging -> Option B

4. Quick Check:

   Logging = Monitoring and debugging [OK]

Hint: Logging tools track app events and errors [OK]

Common Mistakes:

• Confusing logging with database or HTTP handling
• Thinking logging compiles code
• Assuming logging manages app logic

2.

Which of the following is the correct way to import and use Logger from @nestjs/common for basic logging?

?

easy

A. import { Logger } from '@nestjs/common'; const logger = new Logger('App'); logger.log('App started');

B. import Logger from 'nestjs'; const logger = Logger(); logger.log('App started');

C. const Logger = require('@nestjs/common'); const logger = new Logger(); logger.info('App started');

D. import { Logger } from 'winston'; const logger = new Logger(); logger.log('App started');

Solution

1. Step 1: Check correct import syntax

   Correct import is from '@nestjs/common' using named import: import { Logger } from '@nestjs/common';

2. Step 2: Verify usage

   Logger is instantiated with a context string, then log method is called. import { Logger } from '@nestjs/common'; const logger = new Logger('App'); logger.log('App started'); matches this.

3. Final Answer:

   import { Logger } from '@nestjs/common'; const logger = new Logger('App'); logger.log('App started'); -> Option A

4. Quick Check:

   Correct import and usage = import { Logger } from '@nestjs/common'; const logger = new Logger('App'); logger.log('App started'); [OK]

Hint: Use named import from '@nestjs/common' for Logger [OK]

Common Mistakes:

• Using default import instead of named import
• Calling wrong method like info instead of log
• Importing Logger from wrong package

3.

Given this NestJS code using Pino logger, what will be the output in the console?

import { Logger } from 'nestjs-pino';
const logger = new Logger();
logger.info('Server started');
logger.error('Failed to connect');

medium

A. {"level":30,"msg":"Server started"} followed by {"level":50,"msg":"Failed to connect"}

B. Plain text logs: 'Server started' and 'Failed to connect' without JSON

C. SyntaxError due to missing import from '@nestjs/common'

D. No output because logger is not instantiated correctly

Solution

1. Step 1: Understand Pino output format

   Pino logs output JSON strings with level numbers (30=info, 50=error) and message keys.

2. Step 2: Analyze code behavior

   Logger instance calls info and error methods, producing JSON logs with messages.

3. Final Answer:

   {"level":30,"msg":"Server started"} followed by {"level":50,"msg":"Failed to connect"} -> Option A

4. Quick Check:

   Pino logs JSON with level and msg [OK]

Hint: Pino logs JSON with level numbers and message keys [OK]

Common Mistakes:

• Expecting plain text logs instead of JSON
• Confusing Pino with NestJS Logger
• Assuming no output due to import confusion

4.

Identify the error in this NestJS Winston logger setup:

import { WinstonModule } from 'nest-winston';
import * as winston from 'winston';

const logger = WinstonModule.forRoot({
  transports: [
    new winston.transports.Console({ level: 'info' })
  ]
});

logger.error('Error occurred');

medium

A. Incorrect transport name; should be winston.Console instead of winston.transports.Console

B. Missing import of Logger from '@nestjs/common'

C. The logger instance does not have an error method directly; it returns a module, not a logger

D. Level 'info' is invalid for Console transport

Solution

1. Step 1: Understand WinstonModule.forRoot return

   This method returns a NestJS module, not a direct logger instance with methods like error.

2. Step 2: Identify correct usage

   To log, you must inject the logger service or use winston.createLogger directly, not call error on the module.

3. Final Answer:

   The logger instance does not have an error method directly; it returns a module, not a logger -> Option C

4. Quick Check:

   WinstonModule.forRoot returns module, not logger instance [OK]

Hint: WinstonModule.forRoot returns module, not logger instance [OK]

Common Mistakes:

• Calling error method on module instead of logger instance
• Confusing transport names
• Assuming level 'info' is invalid

5.

You want to configure NestJS to use Pino for logging with JSON output and also log HTTP requests. Which setup is correct?

?

hard

A. import * as pino from 'pino';

const logger = pino({ prettyPrint: true });
logger.info('HTTP request logged');

B. import { WinstonModule } from 'nest-winston';

WinstonModule.forRoot({
transports: [new winston.transports.File({ filename: 'log.json' })]
});

C. import { Logger } from '@nestjs/common';

const logger = new Logger();
logger.log('HTTP request logged');

D. import { LoggerModule } from 'nestjs-pino';

LoggerModule.forRoot({
pinoHttp: {
level: 'info'
}
});

Solution

1. Step 1: Identify Pino module usage in NestJS

   Use LoggerModule from 'nestjs-pino' with forRoot and pinoHttp config for HTTP logging and JSON output.

2. Step 2: Check options for JSON and pretty printing

   import { LoggerModule } from 'nestjs-pino'; LoggerModule.forRoot({ pinoHttp: { level: 'info' } }); configures nestjs-pino LoggerModule with pinoHttp for HTTP request logging at info level, producing JSON output by default, matching requirements.

3. Final Answer:

   import { LoggerModule } from 'nestjs-pino'; LoggerModule.forRoot({ pinoHttp: { level: 'info' } }); -> Option D

4. Quick Check:

   nestjs-pino with pinoHttp config = import { LoggerModule } from 'nestjs-pino'; LoggerModule.forRoot({ pinoHttp: { level: 'info' } }); [OK]

Hint: Use nestjs-pino LoggerModule with pinoHttp config for HTTP logs [OK]

Common Mistakes:

• Using WinstonModule instead of nestjs-pino for Pino logging
• Using Logger from '@nestjs/common' for HTTP logs
• Using pino directly without NestJS integration