Enhancing Pino to Support (Message, Payload) Logging Without Breaking Pretty Logs

Introduction Pino is a blazing-fast logging library for Node.js, built for structured logs and high performance. However, one common frustration developers face is that Pino does not natively support logging a message alongside an object the way console.log does. Note: this is my approach and a solution that works well for me. If you have any suggestions, improvements, or use a different method in your projects, I’d love to hear your thoughts! The Problem If you log with: logger.info('User created', { userId: 123 }); You expect: INFO [12:30:45] User created { userId: 123 } But instead, Pino ignores the second argument: INFO [12:30:45] User created Even worse, if you're using pino-pretty, the output doesn’t format correctly when using string interpolation (%s, %j). Understanding Why Pino Ignores Extra Arguments Pino follows a strict logging format: One argument → If it's an object, it's logged as JSON. One argument → If it's a string, it’s logged as a msg field. More than one argument → Only placeholders (%s, %d, %j) are used. logger.info('Hello %s', 'world'); // ✅ Logs correctly logger.info('Hello', { world: true }); // ❌ Logs only "Hello" Unlike console.log, Pino does not merge a message with an object unless explicitly structured. Major Problem: pino-pretty Ignores Error Serializers ❌ Default Behavior: Errors Are Not Properly Serialized Pino does not properly serialize errors when logged using %j: logger.debug('hello %j', new Error('some crazy error'));

Mar 19, 2025 - 13:33

Enhancing Pino to Support (Message, Payload) Logging Without Breaking Pretty Logs

Introduction

Pino is a blazing-fast logging library for Node.js, built for structured logs and high performance. However, one common frustration developers face is that Pino does not natively support logging a message alongside an object the way console.log does.

Note: this is my approach and a solution that works well for me. If you have any suggestions, improvements, or use a different method in your projects, I’d love to hear your thoughts!

The Problem

If you log with:

logger.info('User created', { userId: 123 });

You expect:

INFO  [12:30:45]  User created { userId: 123 }

But instead, Pino ignores the second argument:

INFO  [12:30:45]  User created

Even worse, if you're using pino-pretty, the output doesn’t format correctly when using string interpolation (%s, %j).

Understanding Why Pino Ignores Extra Arguments

Pino follows a strict logging format:

One argument → If it's an object, it's logged as JSON.
One argument → If it's a string, it’s logged as a msg field.
More than one argument → Only placeholders (%s, %d, %j) are used.

logger.info('Hello %s', 'world'); // ✅ Logs correctly
logger.info('Hello', { world: true }); // ❌ Logs only "Hello"

Unlike console.log, Pino does not merge a message with an object unless explicitly structured.

Major Problem: `pino-pretty` Ignores Error Serializers

❌ Default Behavior: Errors Are Not Properly Serialized

Pino does not properly serialize errors when logged using %j:

logger.debug('hello %j', new Error('some crazy error'));