transactional-server.go

package main

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

	_ "github.com/lib/pq"
)

const pgSqlDsn = "user=leehambley dbname=tt sslmode=disable"

func main() {

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

	mux := http.NewServeMux()
	mux.HandleFunc("/foo", func(w http.ResponseWriter, req *http.Request) {
		tx, _ := db.Begin()
		defer tx.Commit()
		FooHandler{tx: tx}.ServeHTTP(w, req)
	})

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

type FooHandler struct {
	tx *sql.Tx
}

func (self FooHandler) ServeHTTP(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
	}

	// ...

	err = self.tx.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)
	}
}

transactional-server_test.go

package main

import (
	"database/sql"
	"log"
	"net/http"
	"net/http/httptest"
	"testing"

	_ "github.com/lib/pq"
)

func Test_FooHandler_200_OK(t *testing.T) {

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

	tx, _ := db.Begin()
	defer tx.Rollback()

	ts := httptest.NewServer(http.Handler(&FooHandler{tx: tx}))
	defer ts.Close()

	if _, err := tx.Exec("INSERT INTO widgets (id, name) VALUES (123, 'Test Widget')"); err != nil {
		t.Fatalf("Failed to insert test widget: %s\n", err)
	}

	res, err := http.Get(ts.URL + "?id=123")
	if err != nil {
		log.Fatal(err)
	}
	if res.StatusCode != http.StatusOK {
		t.Fatalf("Expected code %d, got %d\n", http.StatusOK, res.StatusCode)
	}
}