// Package spanner contains an example of using Spanner from a Cloud Function.
package spanner
import (
"context"
"fmt"
"log"
"net/http"
"sync"
"cloud.google.com/go/spanner"
"github.com/GoogleCloudPlatform/functions-framework-go/functions"
"google.golang.org/api/iterator"
)
// client is a global Spanner client, to avoid initializing a new client for
// every request.
var client *spanner.Client
var clientOnce sync.Once
// db is the name of the database to query.
var db = "projects/my-project/instances/my-instance/databases/example-db"
func init() {
functions.HTTP("HelloSpanner", HelloSpanner)
}
// HelloSpanner is an example of querying Spanner from a Cloud Function.
func HelloSpanner(w http.ResponseWriter, r *http.Request) {
clientOnce.Do(func() {
// Declare a separate err variable to avoid shadowing client.
var err error
client, err = spanner.NewClient(context.Background(), db)
if err != nil {
http.Error(w, "Error initializing database", http.StatusInternalServerError)
log.Printf("spanner.NewClient: %v", err)
return
}
})
fmt.Fprintln(w, "Albums:")
stmt := spanner.Statement{SQL: `SELECT SingerId, AlbumId, AlbumTitle FROM Albums`}
iter := client.Single().Query(r.Context(), stmt)
defer iter.Stop()
for {
row, err := iter.Next()
if err == iterator.Done {
return
}
if err != nil {
http.Error(w, "Error querying database", http.StatusInternalServerError)
log.Printf("iter.Next: %v", err)
return
}
var singerID, albumID int64
var albumTitle string
if err := row.Columns(&singerID, &albumID, &albumTitle); err != nil {
http.Error(w, "Error parsing database response", http.StatusInternalServerError)
log.Printf("row.Columns: %v", err)
return
}
fmt.Fprintf(w, "%d %d %s\n", singerID, albumID, albumTitle)
}
}
