basic go postgres and logging example

go.mod

module monitor

go 1.13

require (
	github.com/jackc/pgx/v4 v4.1.2
	github.com/jinzhu/gorm v1.9.11
	github.com/joho/godotenv v1.3.0
	go.uber.org/zap v1.13.0
)

monitor.go

// this is for fun.
package main

import (
	"context"
	"fmt"
	"os"
	"time"

	"github.com/jackc/pgx/v4"
	"github.com/joho/godotenv"
	"go.uber.org/zap"
)

// The Queue struct represents a table in the database.
//
// It is meant to be used with gorm.
type Queue struct {
	ID       uint `gorm:"primary_key"`
	Message  string
	Status   string
	Inserted time.Time
}

func (Queue) TableName() string {
	return "queue"
}

func main() {
	devlog, _ := zap.NewProduction()
	sugar := devlog.Sugar()
	defer sugar.Sync()
	sugar.Infow("failed to fetch URL",
		"url", "http://example.com",
		"attempt", 3,
		"backoff", time.Second,
	)

	err := godotenv.Load()

	if err != nil {
		sugar.Infow("failed to find .env file")
	}

	conn, err := pgx.Connect(context.Background(), os.Getenv("DATABASE_URL"))
	if err != nil {
		sugar.Infof("Unable to connection to database: %v\n", err)
		os.Exit(1)
	}

	defer conn.Close(context.Background())

	rows, err := conn.Query(context.Background(),
		"select status, count(*) as count "+
			"from queue where status is not NULL "+
			"group by status")
	if err != nil {
		sugar.Fatal(err)
	}

	// rows.Close is called by rows.Next when all rows are read
	// or an error occurs in Next or Scan. So it may optionally be
	// omitted if nothing in the rows.Next loop can panic. It is
	// safe to close rows multiple times.
	defer rows.Close()


	// rows.Next() prepares the next row for scanning.
	// Scanning simply loads the row contents into the
	// prepared variables, passed as pointers.
	var count uint
	var status string
	for rows.Next() {
		err = rows.Scan(&status, &count)
		fmt.Printf("%20s%15d\n", status, count)
	}
}