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Requête avec le paramètre BYTES

Interroger les données à l'aide d'un paramètre BYTES.

Exemple de code

C++

Pour savoir comment installer et utiliser la bibliothèque cliente pour Spanner, consultez la page Bibliothèques clientes Spanner.

Pour vous authentifier auprès de Spanner, configurez les Identifiants par défaut de l'application. Pour en savoir plus, consultez Configurer l'authentification pour un environnement de développement local.

void QueryWithBytesParameter(google::cloud::spanner::Client client) {
  namespace spanner = ::google::cloud::spanner;
  spanner::Bytes example_bytes("Hello World 1");
  spanner::SqlStatement select(
      "SELECT VenueId, VenueName FROM Venues"
      " WHERE VenueInfo = @venue_info",
      {{"venue_info", spanner::Value(example_bytes)}});
  using RowType = std::tuple<std::int64_t, absl::optional<std::string>>;
  auto rows = client.ExecuteQuery(std::move(select));
  for (auto& row : spanner::StreamOf<RowType>(rows)) {
    if (!row) throw std::move(row).status();
    std::cout << "VenueId: " << std::get<0>(*row) << "\t";
    std::cout << "VenueName: " << std::get<1>(*row).value() << "\n";
  }
  std::cout << "Query completed for [spanner_query_with_bytes_parameter]\n";
}

C#

Pour savoir comment installer et utiliser la bibliothèque cliente pour Spanner, consultez la page Bibliothèques clientes Spanner.


using Google.Cloud.Spanner.Data;
using System.Collections.Generic;
using System.Text;
using System.Threading.Tasks;

public class QueryWithBytesAsyncSample
{
    public class Venue
    {
        public int VenueId { get; set; }
        public string VenueName { get; set; }
    }

    public async Task<List<Venue>> QueryWithBytesAsync(string projectId, string instanceId, string databaseId)
    {
        string connectionString = $"Data Source=projects/{projectId}/instances/{instanceId}/databases/{databaseId}";
        // Initialize a Bytes array to use for querying.
        string sampleText = "Hello World 1";
        byte[] exampleBytes = Encoding.UTF8.GetBytes(sampleText);

        using var connection = new SpannerConnection(connectionString);
        var cmd = connection.CreateSelectCommand("SELECT VenueId, VenueName FROM Venues WHERE VenueInfo = @ExampleBytes");
        cmd.Parameters.Add("ExampleBytes", SpannerDbType.Bytes, exampleBytes);

        var venues = new List<Venue>();
        using var reader = await cmd.ExecuteReaderAsync();
        while (await reader.ReadAsync())
        {
            venues.Add(new Venue
            {
                VenueId = reader.GetFieldValue<int>("VenueId"),
                VenueName = reader.GetFieldValue<string>("VenueName")
            });
        }
        return venues;
    }
}

Go

Pour savoir comment installer et utiliser la bibliothèque cliente pour Spanner, consultez la page Bibliothèques clientes Spanner.


import (
	"context"
	"fmt"
	"io"

	"cloud.google.com/go/spanner"
	"google.golang.org/api/iterator"
)

func queryWithBytes(w io.Writer, db string) error {
	ctx := context.Background()
	client, err := spanner.NewClient(ctx, db)
	if err != nil {
		return err
	}
	defer client.Close()

	var exampleBytes = []byte("Hello World 1")
	stmt := spanner.Statement{
		SQL: `SELECT VenueId, VenueName FROM Venues
            	WHERE VenueInfo = @venueInfo`,
		Params: map[string]interface{}{
			"venueInfo": exampleBytes,
		},
	}
	iter := client.Single().Query(ctx, stmt)
	defer iter.Stop()
	for {
		row, err := iter.Next()
		if err == iterator.Done {
			return nil
		}
		if err != nil {
			return err
		}
		var venueID int64
		var venueName string
		if err := row.Columns(&venueID, &venueName); err != nil {
			return err
		}
		fmt.Fprintf(w, "%d %s\n", venueID, venueName)
	}
}

Java

Pour savoir comment installer et utiliser la bibliothèque cliente pour Spanner, consultez la page Bibliothèques clientes Spanner.

static void queryWithBytes(DatabaseClient dbClient) {
  ByteArray exampleBytes =
      ByteArray.fromBase64(BaseEncoding.base64().encode("Hello World 1".getBytes()));
  Statement statement =
      Statement.newBuilder(
              "SELECT VenueId, VenueName FROM Venues " + "WHERE VenueInfo = @venueInfo")
          .bind("venueInfo")
          .to(exampleBytes)
          .build();
  try (ResultSet resultSet = dbClient.singleUse().executeQuery(statement)) {
    while (resultSet.next()) {
      System.out.printf(
          "%d %s\n", resultSet.getLong("VenueId"), resultSet.getString("VenueName"));
    }
  }
}

Node.js

Pour savoir comment installer et utiliser la bibliothèque cliente pour Spanner, consultez la page Bibliothèques clientes Spanner.

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

/**
 * TODO(developer): Uncomment the following lines before running the sample.
 */
// const projectId = 'my-project-id';
// const instanceId = 'my-instance';
// const databaseId = 'my-database';

// Creates a client
const spanner = new Spanner({
  projectId: projectId,
});

// Gets a reference to a Cloud Spanner instance and database.
const instance = spanner.instance(instanceId);
const database = instance.database(databaseId);

const fieldType = {
  type: 'bytes',
};

const exampleBytes = new Buffer.from('Hello World 1');

const query = {
  sql: `SELECT VenueId, VenueName FROM Venues
          WHERE VenueInfo = @venueInfo`,
  params: {
    venueInfo: exampleBytes,
  },
  types: {
    venueInfo: fieldType,
  },
};

// Queries rows from the Venues table.
try {
  const [rows] = await database.run(query);

  rows.forEach(row => {
    const json = row.toJSON();
    console.log(`VenueId: ${json.VenueId}, VenueName: ${json.VenueName}`);
  });
} catch (err) {
  console.error('ERROR:', err);
} finally {
  // Close the database when finished.
  database.close();
}

PHP

Pour savoir comment installer et utiliser la bibliothèque cliente pour Spanner, consultez la page Bibliothèques clientes Spanner.

use Google\Cloud\Spanner\SpannerClient;
use Google\Cloud\Spanner\Database;

/**
 * Queries sample data from the database using SQL with a BYTES parameter.
 * Example:
 * ```
 * query_data_with_bytes_parameter($instanceId, $databaseId);
 * ```
 *
 * @param string $instanceId The Spanner instance ID.
 * @param string $databaseId The Spanner database ID.
 */
function query_data_with_bytes_parameter(string $instanceId, string $databaseId): void
{
    $spanner = new SpannerClient();
    $instance = $spanner->instance($instanceId);
    $database = $instance->database($databaseId);

    $exampleBytes = base64_encode('Hello World 1');

    $results = $database->execute(
        'SELECT VenueId, VenueName FROM Venues ' .
        'WHERE VenueInfo = @venueInfo',
        [
            'parameters' => [
                'venueInfo' => $exampleBytes
            ],
            'types' => [
                'venueInfo' => Database::TYPE_BYTES
            ]
        ]
    );

    foreach ($results as $row) {
        printf('VenueId: %s, VenueName: %s' . PHP_EOL,
            $row['VenueId'], $row['VenueName']);
    }
}

Python

Pour savoir comment installer et utiliser la bibliothèque cliente pour Spanner, consultez la page Bibliothèques clientes Spanner.

# instance_id = "your-spanner-instance"
# database_id = "your-spanner-db-id"
spanner_client = spanner.Client()
instance = spanner_client.instance(instance_id)
database = instance.database(database_id)

exampleBytes = base64.b64encode("Hello World 1".encode())
param = {"venue_info": exampleBytes}
param_type = {"venue_info": param_types.BYTES}

with database.snapshot() as snapshot:
    results = snapshot.execute_sql(
        "SELECT VenueId, VenueName FROM Venues " "WHERE VenueInfo = @venue_info",
        params=param,
        param_types=param_type,
    )

    for row in results:
        print("VenueId: {}, VenueName: {}".format(*row))

Ruby

Pour savoir comment installer et utiliser la bibliothèque cliente pour Spanner, consultez la page Bibliothèques clientes Spanner.

# project_id  = "Your Google Cloud project ID"
# instance_id = "Your Spanner instance ID"
# database_id = "Your Spanner database ID"

require "google/cloud/spanner"

spanner = Google::Cloud::Spanner.new project: project_id
client  = spanner.client instance_id, database_id

example_bytes = StringIO.new "Hello World 1"
sql_query = "SELECT VenueId, VenueName FROM Venues
             WHERE VenueInfo = @venue_info"

params      = { venue_info: example_bytes }
param_types = { venue_info: :BYTES }

client.execute(sql_query, params: params, types: param_types).rows.each do |row|
  puts "#{row[:VenueId]} #{row[:VenueName]}"
end

Étapes suivantes

Pour rechercher et filtrer des exemples de code pour d'autres produits Google Cloud, consultez l'exemple de navigateur Google Cloud.