database.sql

CREATE DATABASE tt;

\c tt

CREATE TABLE widgets (
  id   INT  PRIMARY KEY NOT NULL,
  name TEXT             NOT NULL
);

INSERT INTO widgets (id, name) VALUES (456, 'AeroPress');

naïve-server.go

package main

import (
	"database/sql"
	"fmt"
	"log"
	"net/http"
	"strconv"

	_ "github.com/lib/pq"
)

const pgSqlDsn = "dbname=tt sslmode=disable"

func main() {
	mux := http.NewServeMux()
	mux.HandleFunc("/foo", FooHandler)
	err := http.ListenAndServe(":3000", mux)
	if err != nil {
		log.Fatalf("Couldn't start server: %v\n", err)
	} else {
		log.Println("Listening...")
	}
}

func FooHandler(w http.ResponseWriter, req *http.Request) {

	var widgetName string

	widgetIdStr := req.FormValue("id")
	widgetId, err := strconv.ParseInt(widgetIdStr, 10, 0)
	if err != nil {
		w.WriteHeader(http.StatusBadRequest)
		if len(widgetIdStr) == 0 {
			widgetIdStr = "(empty)"
		}
		fmt.Fprintf(w, "`%s' is not a valid widget ID\n", widgetIdStr)
		return
	}

	db, err := sql.Open("postgres", pgSqlDsn)
	if err != nil {
		log.Fatalf("Error opening database handle: %s\n", err)
	}

	err = db.QueryRow("SELECT name FROM widgets WHERE id = $1", widgetId).Scan(&widgetName)
	switch {
	case err == sql.ErrNoRows:
		w.WriteHeader(http.StatusNotFound)
		fmt.Fprintf(w, "No widget with ID %d\n", widgetId)
	case err != nil:
		w.WriteHeader(http.StatusInternalServerError)
		fmt.Fprintf(w, http.StatusText(http.StatusInternalServerError), widgetId)
		log.Fatalf("Database Error:", err)
	default:
		fmt.Fprintf(w, "Widget Name: %s\n", widgetName)
	}
}