Best practice: Create custom errors using well-defined error types (errors package) Provide more details Properly log errors Properly propagate errors, avoid hiding or suppressing Wrap errors as needed to add context

Best Practices for Error Handling in the Go Framework

Handling errors in Go applications is critical to writing stable, robust code. The Go standard library provides built-in support for error handling, but different frameworks can have their own best practices. This article describes some guidelines for optimal error handling when using the Go framework.

1. Use error types

It is recommended to use clearly defined error types, which can simplify error handling and improve readability. Error types can be created through the New or Errorf functions in the errors package.

For example:

import "errors"

var ErrNotFound = errors.New("not found")

2. Using custom errors

Writing your own error types in the framework can provide more detailed error types than the built-in error types. information. This allows applications to handle errors in a more meaningful way.

For example:

type MyError struct {
    Message string
}

func (e MyError) Error() string {
    return e.Message
}

3. Proper logging

An important aspect of error handling is logging. The framework should provide logging functionality to record all errors that occur. This helps debug issues and track application behavior.

For example, use the log package:

import "log"

func main() {
    log.Fatal(ErrNotFound)
}

4. Error propagation

The function should propagate errors correctly, allowing upper-layer functions deal with them. Avoid hiding or suppressing errors as it makes debugging difficult.

func GetResource() (*Resource, error) {
    db, err := connectToDB()
    if err != nil {
        return nil, err
    }

    resource, err := db.GetResource()
    if err != nil {
        return nil, err
    }

    return resource, nil
}

5. Error packaging

Sometimes, it is necessary to add contextual information to an existing error. Error wrapping (also called error accumulation) allows adding additional layers of errors on top of the original error.

import "fmt"

func GetResource() (*Resource, error) {
    resource, err := db.GetResource()
    if err != nil {
        return nil, fmt.Errorf("failed to get resource: %w", err)
    }

    return resource, nil
}

Practical Case

Consider a REST API built using the Gin framework that handles errors from the database:

import (
    "errors"
    "github.com/gin-gonic/gin"
)

var ErrNotFound = errors.New("not found")

func GetResource(c *gin.Context) {
    db, err := connectToDB()
    if err != nil {
        c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
        return
    }

    resource, err := db.GetResource(c.Param("id"))
    if err == ErrNotFound {
        c.JSON(http.StatusNotFound, gin.H{"error": "resource not found"})
        return
    }

    if err != nil {
        c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
        return
    }

    c.JSON(http.StatusOK, resource)
}

This example demonstrates :

• Use custom error typesErrNotFound
• Properly propagate errors, returning them to Gin's response handler
• According to the error type Return the appropriate HTTP status code

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