How do you handle errors in Go?

Q: How do you handle errors in Go?

Learn the answer to "How do you handle errors in Go?" with detailed explanations, code examples, and best practices on DeployU.

The Scenario

You are a backend engineer at a fintech company. You are writing a new service that needs to interact with a database. You need to make sure that you handle errors correctly at each step of the process.

The Challenge

Explain how you would handle errors in Go. What are the different error handling patterns that you would use, and what are the key benefits of Go’s approach to error handling?

Wrong Approach

A junior engineer might just ignore errors or use `panic` to handle them. They might not be aware of the importance of handling errors explicitly or the benefits of Go's approach to error handling.

Addresses symptoms, not root cause

Right Approach

A senior engineer would know that error handling is a critical part of writing robust and reliable code in Go. They would be able to explain the different error handling patterns and would have a clear plan for how to handle errors in a consistent and predictable way.

Step 1: Understand Go’s Approach to Error Handling

Go’s approach to error handling is different from many other languages. In Go, errors are returned as the second return value from a function. This makes it explicit that a function can fail, and it forces the caller to handle the error.

Step 2: The `error` Interface

The error interface is the standard way to represent an error in Go. It is a simple interface with a single method:

type error interface {
    Error() string
}

Step 3: Error Handling Patterns

Here are some common error handling patterns in Go:

1. Explicitly check for errors:

val, err := myFunction()
if err != nil {
    // ... (handle the error) ...
}

2. Create custom error types:

You can create custom error types to provide more context about an error.

type MyError struct {
    Msg string
    File string
    Line int
}

func (e *MyError) Error() string {
    return fmt.Sprintf("%s:%d: %s", e.File, e.Line, e.Msg)
}

3. Use the errors package:

The errors package provides functions for creating and wrapping errors.

import "errors"

var ErrMyError = errors.New("my error")

The Benefits of Go’s Approach to Error Handling

Benefit	Description
Explicitness	Errors are explicit, which makes it easy to see which functions can fail and to handle the errors accordingly.
Simplicity	The `error` interface is simple and easy to use.
Consistency	The standard of returning an error as the second return value makes the error handling code consistent and predictable.

Systematic, production-ready debugging

Practice Question

You are writing a function that can fail in multiple ways. Which of the following would be the most appropriate?

Questions