log

Documentation

Overview

Package log is a module injecting a `*slog.Logger` instance. It provides a group of functions to log with the injected instance. See [examples_test.go](./examples_test.go) for the usage.

Index

• Variables
• func DEBUG(ctx context.Context, msg string, args ...any)
• func ERROR(ctx context.Context, msg string, args ...any)
• func INFO(ctx context.Context, msg string, args ...any)
• func WARN(ctx context.Context, msg string, args ...any)
• func With(ctx context.Context, args ...any) context.Context

Examples

• With

Variables

var (
	// Module for injecting `*slog.Logger`
	Module = module.New[*slog.Logger]()

	// TextLogger provides a instance with `slog.TextHandler` logging to `os.Stderr`
	TextLogger = Module.ProvideWithFunc(func(ctx context.Context) (*slog.Logger, error) {
		handler := slog.NewTextHandler(os.Stderr, nil)
		return slog.New(handler), nil
	})

	// JSONLogger provides a instance with `slog.JSONHandler` logging to `os.Stderr`
	JSONLogger = Module.ProvideWithFunc(func(ctx context.Context) (*slog.Logger, error) {
		handler := slog.NewJSONHandler(os.Stderr, nil)
		return slog.New(handler), nil
	})
)

Functions

func DEBUG

func DEBUG(ctx context.Context, msg string, args ...any)

DEBUG logs with the injected instance at DEBUG level. If no injected `*slog.Logger`, the function does nothing.

func ERROR

func ERROR(ctx context.Context, msg string, args ...any)

ERROR logs with the injected instance at ERROR level. If no injected `*slog.Logger`, the function does nothing.

func INFO

func INFO(ctx context.Context, msg string, args ...any)

INFO logs with the injected instance at INFO level. If no injected `*slog.Logger`, the function does nothing.

func WARN

func WARN(ctx context.Context, msg string, args ...any)

WARN logs with the injected instance at WARN level. If no injected `*slog.Logger`, the function does nothing.

func With

func With(ctx context.Context, args ...any) context.Context

With creates a new `context.Context` with new attrs. It's similar to [`slog.Logger.With()`](https://pkg.go.dev/log/slog#Logger.With).

Example

package main

import (
	"context"
	"log/slog"
	"os"

	"github.com/googollee/module"
	"github.com/googollee/module/log"
)

func removeTimeAttr(groups []string, a slog.Attr) slog.Attr {

	if a.Key == slog.TimeKey {
		return slog.Attr{}
	}

	return a
}

func main() {
	loggerOption := slog.HandlerOptions{
		AddSource:   false, // Remove code position from the output for predictable test output.
		ReplaceAttr: removeTimeAttr,
	}

	repo := module.NewRepo()
	// repo.Add(log.TextLogger)) in common usage
	// Provide a customed slog.Logger for predictable test output.
	repo.Add(log.Module.ProvideValue(slog.New(slog.NewTextHandler(os.Stdout, &loggerOption))))

	ctx, err := repo.InjectTo(context.Background())
	if err != nil {
		return
	}

	log.INFO(ctx, "before")
	{
		ctx := log.With(ctx, "span", "abc")
		log.INFO(ctx, "in")
	}
	log.INFO(ctx, "after")

}

Output:

level=INFO msg=before
level=INFO msg=in span=abc
level=INFO msg=after