Golang http server with sql null values and json

go_null_json_example.go

package main

import (
	"database/sql"
	"encoding/json"
	"log"
	"net/http"
	"strconv"

	_ "github.com/mattn/go-sqlite3"
	"gopkg.in/guregu/null.v3"
)

// DB is the database connector
var DB *sql.DB

// Person represents a single row in a database. Using the type null.
type Person struct {
	Name     string      `json:"id"`
	Age      int         `json:"age"`
	NickName null.String `json:"nickname"` // Optional
}

// InsertPerson adds a person to the database
func InsertPerson(p Person) {
	cnx, _ := DB.Prepare(`
          INSERT INTO people (name, age, nickname) VALUES (?, ?, ?)`)
	defer cnx.Close()
  
	log.Printf("Adding person: %v\n", p)
	cnx.Exec(p.Name, p.Age, p.NickName)
}

// GetPeople will retur N number of people from database
func GetPeople(n int) []Person {
	people := make([]Person, 0)
	rows, _ := DB.Query(`SELECT name, age, nickname from people LIMIT ?`, n)
	for rows.Next() {
		p := new(Person)
		rows.Scan(&p.Name, &p.Age, &p.NickName)
		people = append(people, *p)
	}
	return people
}

func addPersonRouter(w http.ResponseWriter, r *http.Request) {
	r.ParseForm()

	age, _ := strconv.Atoi(r.FormValue("age"))

	// Get nickname from the form and create a new null.String. If the string
	// is empty, it will be considered invalid (null) in the database and not
	// empty
	nick := r.FormValue("nickname")
	nickName := null.NewString(
		nick, nick != "")

	p := Person{
		Name:     r.FormValue("name"),
		Age:      age,
		NickName: nickName,
	}

	InsertPerson(p)

	w.WriteHeader(http.StatusCreated)
}

func getPeopleRouter(w http.ResponseWriter, r *http.Request) {
	r.ParseForm()
	limit, _ := strconv.Atoi(r.FormValue("limit"))
	people := GetPeople(limit)

	peopleJSON, _ := json.Marshal(people)
	w.Header().Set("Content-Type", "application/json")
	w.Write(peopleJSON)
}

// CreateTable is a helper function to create the table for the first run
func CreateTable() error {

	createSQL := `
    CREATE TABLE people (
        id INTEGER PRIMARY KEY AUTOINCREMENT,
		name TXT NOT NULL,
		age INTEGER NOT NULL,
		nickname TXT
	);`
  
	statement, err := DB.Prepare(createSQL)
	if err != nil {
		return err
	}

	statement.Exec()
	statement.Close()

	return nil
}

func main() {
	var err error
	DB, err = sql.Open("sqlite3", ":memory:")
	if err != nil {
		log.Fatal(err)
	}

	err = CreateTable()
	if err != nil {
		log.Fatal(err)
	}

	http.HandleFunc("/add", addPersonRouter)
	http.HandleFunc("/list", getPeopleRouter)
	http.ListenAndServe(":8080", nil)
}