Funzioni

Eseguire il collegamento utilizzando le funzioni.

Per saperne di più

Per la documentazione dettagliata che include questo esempio di codice, consulta quanto segue:

Esempio di codice

Go

Per scoprire come installare e utilizzare la libreria client per Spanner, consulta Librerie client Spanner.

Per autenticarti a Spanner, configura le credenziali predefinite dell'applicazione. Per ulteriori informazioni, vedi Configura l'autenticazione per un ambiente di sviluppo locale. 


// 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)
	}
}

Java

Per scoprire come installare e utilizzare la libreria client per Spanner, consulta Librerie client Spanner.

Per eseguire l'autenticazione su Spanner, configura Credenziali predefinite dell'applicazione. Per maggiori informazioni, consulta Configurare l'autenticazione per un ambiente di sviluppo locale. 

import com.google.api.client.http.HttpStatusCodes;
import com.google.cloud.functions.HttpFunction;
import com.google.cloud.functions.HttpRequest;
import com.google.cloud.functions.HttpResponse;
import com.google.cloud.spanner.DatabaseClient;
import com.google.cloud.spanner.DatabaseId;
import com.google.cloud.spanner.LazySpannerInitializer;
import com.google.cloud.spanner.ResultSet;
import com.google.cloud.spanner.SpannerException;
import com.google.cloud.spanner.SpannerOptions;
import com.google.cloud.spanner.Statement;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.MoreObjects;
import java.io.PrintWriter;
import java.util.logging.Level;
import java.util.logging.Logger;

// HelloSpanner is an example of querying Spanner from a Cloud Function.
public class HelloSpanner implements HttpFunction {
  private static final Logger logger = Logger.getLogger(HelloSpanner.class.getName());

  // TODO<developer>: Set these environment variables.
  private static final String SPANNER_INSTANCE_ID =
      MoreObjects.firstNonNull(System.getenv("SPANNER_INSTANCE"), "my-instance");
  private static final String SPANNER_DATABASE_ID =
      MoreObjects.firstNonNull(System.getenv("SPANNER_DATABASE"), "example-db");

  private static final DatabaseId databaseId =
      DatabaseId.of(
          SpannerOptions.getDefaultProjectId(),
          SPANNER_INSTANCE_ID,
          SPANNER_DATABASE_ID);

  // The LazySpannerInitializer instance is shared across all instances of the HelloSpanner class.
  // It will create a Spanner instance the first time one is requested, and continue to return that
  // instance for all subsequent requests.
  private static final LazySpannerInitializer SPANNER_INITIALIZER = new LazySpannerInitializer();

  @VisibleForTesting
  DatabaseClient getClient() throws Throwable {
    return SPANNER_INITIALIZER.get().getDatabaseClient(databaseId);
  }

  @Override
  public void service(HttpRequest request, HttpResponse response) throws Exception {
    var writer = new PrintWriter(response.getWriter());
    try {
      DatabaseClient client = getClient();
      try (ResultSet rs =
          client
              .singleUse()
              .executeQuery(Statement.of("SELECT SingerId, AlbumId, AlbumTitle FROM Albums"))) {
        writer.printf("Albums:%n");
        while (rs.next()) {
          writer.printf(
              "%d %d %s%n",
              rs.getLong("SingerId"), rs.getLong("AlbumId"), rs.getString("AlbumTitle"));
        }
      } catch (SpannerException e) {
        writer.printf("Error querying database: %s%n", e.getMessage());
        response.setStatusCode(HttpStatusCodes.STATUS_CODE_SERVER_ERROR, e.getMessage());
      }
    } catch (Throwable t) {
      logger.log(Level.SEVERE, "Spanner example failed", t);
      writer.printf("Error setting up Spanner: %s%n", t.getMessage());
      response.setStatusCode(HttpStatusCodes.STATUS_CODE_SERVER_ERROR, t.getMessage());
    }
  }
}

Node.js

Per scoprire come installare e utilizzare la libreria client per Spanner, consulta Librerie client di Spanner.

Per eseguire l'autenticazione su Spanner, configura Credenziali predefinite dell'applicazione. Per maggiori informazioni, consulta Configurare l'autenticazione per un ambiente di sviluppo locale. 

// Imports the Google Cloud client library
const {Spanner} = require('@google-cloud/spanner');

// Imports the functions framework to register your HTTP function
const functions = require('@google-cloud/functions-framework');

// Instantiates a client
const spanner = new Spanner();

// Your Cloud Spanner instance ID
const instanceId = 'test-instance';

// Your Cloud Spanner database ID
const databaseId = 'example-db';

/**
 * HTTP Cloud Function.
 *
 * @param {Object} req Cloud Function request context.
 * @param {Object} res Cloud Function response context.
 */
functions.http('spannerQuickstart', async (req, res) => {
  // Gets a reference to a Cloud Spanner instance and database
  const instance = spanner.instance(instanceId);
  const database = instance.database(databaseId);

  // The query to execute
  const query = {
    sql: 'SELECT * FROM Albums',
  };

  // Execute the query
  try {
    const results = await database.run(query);
    const rows = results[0].map(row => row.toJSON());
    rows.forEach(row => {
      res.write(
        `SingerId: ${row.SingerId}, ` +
          `AlbumId: ${row.AlbumId}, ` +
          `AlbumTitle: ${row.AlbumTitle}\n`
      );
    });
    res.status(200).end();
  } catch (err) {
    res.status(500).send(`Error querying Spanner: ${err}`);
  }
});

Python

Per scoprire come installare e utilizzare la libreria client per Spanner, consulta Librerie client di Spanner.

Per eseguire l'autenticazione su Spanner, configura Credenziali predefinite dell'applicazione. Per ulteriori informazioni, vedi Configura l'autenticazione per un ambiente di sviluppo locale. 

import functions_framework
from google.cloud import spanner

instance_id = "test-instance"
database_id = "example-db"

client = spanner.Client()
instance = client.instance(instance_id)
database = instance.database(database_id)


@functions_framework.http
def spanner_read_data(request):
    query = "SELECT * FROM Albums"

    outputs = []
    with database.snapshot() as snapshot:
        results = snapshot.execute_sql(query)

        for row in results:
            output = "SingerId: {}, AlbumId: {}, AlbumTitle: {}".format(*row)
            outputs.append(output)

    return "\n".join(outputs)

Passaggi successivi

Per cercare e filtrare esempi di codice per altri prodotti Google Cloud, consulta Browser di esempio Google Cloud.