# README

dbhook

This is a hook for any database/sql driver.
DBhook allows to log requests, measure their duration, control the behavior of requests without changing the code base.
This is the middelware for your database.

Install

go get github.com/loghole/dbhook

Usage

package main

import (
	"context"
	"database/sql"
	"log"
	"time"

	sqlite "github.com/mattn/go-sqlite3"

	"github.com/loghole/dbhook"
)

const durationName = "duration"

type Hook struct {
	log *log.Logger
}

func (h *Hook) Before(ctx context.Context, input *dbhook.HookInput) (context.Context, error) {
	h.log.Printf("before %s: %s", input.Caller, input.Query)

	return context.WithValue(ctx, durationName, time.Now()), nil
}

func (h *Hook) After(ctx context.Context, input *dbhook.HookInput) (context.Context, error) {
	h.log.Printf("after %s: %s. duration: %v", input.Caller, input.Query, time.Since(ctx.Value(durationName).(time.Time)))

	return ctx, nil
}

func (h *Hook) Error(ctx context.Context, input *dbhook.HookInput) (context.Context, error) {
	h.log.Printf("error %s: %v. duration: %v", input.Caller, input.Error, time.Since(ctx.Value(durationName).(time.Time)))

	return ctx, input.Error // if return nil, then the query will not return an error
}

func main() {
	// Init hooks
	hooks := dbhook.NewHooks(dbhook.WithHook(&Hook{log: log.Default()}))

	// Register the wrapper
	sql.Register("sqlite_with_hook", dbhook.Wrap(&sqlite.SQLiteDriver{}, hooks))

	// Connect to the registered wrapped driver
	db, _ := sql.Open("sqlite_with_hook", ":memory:")

	ctx := context.Background()
	// Queries
	db.ExecContext(ctx, "CREATE TABLE t (id INTEGER, text VARCHAR(3))")

	tx, _ := db.BeginTx(context.Background(), nil)
	tx.ExecContext(ctx, "INSERT into t (text) VALUES(?), (?)", "foo", "bar")
	tx.QueryContext(ctx, "SELECT id, text FROM t")
	tx.Commit()

	db.QueryContext(ctx, "SELEC id, text FROM t")
}

/*
  Output:
  before exec: CREATE TABLE t (id INTEGER, text VARCHAR(3))
  after exec: CREATE TABLE t (id INTEGER, text VARCHAR(3)). duration: 66.915µs
  before begin:
  after begin: . duration: 3.456µs
  before exec: INSERT into t (text) VALUES(?), (?)
  after exec: INSERT into t (text) VALUES(?), (?). duration: 13.756µs
  before query: SELECT id, text FROM t
  after query: SELECT id, text FROM t. duration: 6.382µs
  before commit:
  after commit: . duration: 24.786µs
  before query: SELEC id, text FROM t
  error query: near "SELEC": syntax error. duration: 10.57µs
*/