C# hello world

這個程式碼範例是以 C# 撰寫的「Hello World」應用程式，示範如何完成下列工作：

  • 設定驗證方法
  • 連線至 Bigtable 執行個體
  • 建立新的資料表。
  • 將資料寫入資料表。
  • 讀取資料。
  • 刪除資料表。

設定驗證方法

如要在本機開發環境中使用本頁的 .NET 範例，請安裝並初始化 gcloud CLI，然後使用您的使用者憑證設定應用程式預設憑證。

  1. 安裝 Google Cloud CLI。

  2. 若您採用的是外部識別資訊提供者 (IdP)，請先使用聯合身分登入 gcloud CLI。

  3. 如果您使用本機殼層，請為使用者帳戶建立本機驗證憑證： 

    gcloud auth application-default login

    如果您使用 Cloud Shell，則不需要執行這項操作。

    如果系統傳回驗證錯誤，且您使用外部識別資訊提供者 (IdP)，請確認您已 使用聯合身分登入 gcloud CLI。

詳情請參閱 這篇文章，瞭解如何設定本機開發環境的驗證機制。

執行範例

這個程式碼使用 .NET 適用的 Google Cloud 用戶端程式庫中的 C# Admin API 和 C# Data API 程式庫與 Bigtable 進行通訊。

如要執行這個程式範例，請按照 GitHub 上的 .NET Bigtable 範例操作說明進行。完成「建構及執行」和「快速入門」步驟，建立可用於 Hello World 應用程式的資源。請務必編輯 HelloWorld.cs 檔案，新增您建立的資源名稱。

搭配 Cloud 用戶端程式庫使用 Bigtable

這個應用程式範例會連線至 Bigtable，示範部分簡易作業。

連線至 Bigtable

如要開始使用，請建立可用來連線至 Bigtable 的兩個用戶端物件。C# Admin API BigtableTableAdminClient 可協助您建立及刪除執行個體和資料表。C# Google Data API BigtableClient 可協助您讀取及寫入資料表資料。

// BigtableTableAdminClient API lets us create, manage and delete tables.
BigtableTableAdminClient bigtableTableAdminClient = BigtableTableAdminClient.Create();

// BigtableClient API lets us read and write to a table.
BigtableClient bigtableClient = BigtableClient.Create();

建立資料表

在 BigtableTableAdminClient 類別中呼叫 CreateTable() 方法，產生儲存「hello world」問候語的 Table 物件。資料表有單一資料欄系列，會保留每個值的一個版本。

// Create a table with a single column family.
Console.WriteLine($"Create new table: {tableId} with column family: {columnFamily}, instance: {instanceId}");

// Check whether a table with given TableName already exists.
if (!TableExist(bigtableTableAdminClient))
{
    bigtableTableAdminClient.CreateTable(
        new InstanceName(projectId, instanceId),
        tableId,
        new Table
        {
            Granularity = Table.Types.TimestampGranularity.Millis,
            ColumnFamilies =
            {
                {
                    columnFamily, new ColumnFamily
                    {
                        GcRule = new GcRule
                        {
                            MaxNumVersions = 1
                        }
                    }
                }
            }
        });
    // Confirm that table was created successfully.
    Console.WriteLine(TableExist(bigtableTableAdminClient)
        ? $"Table {tableId} created successfully\n"
        : $"There was a problem creating a table {tableId}");
}
else
{
    Console.WriteLine($"Table: {tableId} already exists");
}

將資料列寫入資料表

使用包含三個簡單問候語的字串陣列 s_greetings[]，做為寫入資料表的資料來源。首先，使用 MutateRow() 將單一資料列寫入資料表。接著，循環處理陣列其餘部分，建構每個問候語包含一個項目的 MutateRowsRequest 物件。使用 MutateRows() 提出一次寫入所有項目的要求。接著，循環處理傳回的回應，檢查每個項目的狀態碼，確認是否已成功寫入。

// Initialize Google.Cloud.Bigtable.V2.TableName object.
Google.Cloud.Bigtable.Common.V2.TableName tableName = new Google.Cloud.Bigtable.Common.V2.TableName(projectId, instanceId, tableId);

// Write some rows
/* Each row has a unique row key.

       Note: This example uses sequential numeric IDs for simplicity, but
       this can result in poor performance in a production application.
       Since rows are stored in sorted order by key, sequential keys can
       result in poor distribution of operations across nodes.

       For more information about how to design a Bigtable schema for the
       best performance, see the documentation:

       https://cloud.google.com/bigtable/docs/schema-design */

Console.WriteLine($"Write some greetings to the table {tableId}");

// Insert 1 row using MutateRow()
s_greetingIndex = 0;
try
{
    bigtableClient.MutateRow(tableName, rowKeyPrefix + s_greetingIndex, MutationBuilder());
    Console.WriteLine($"\tGreeting:   -- {s_greetings[s_greetingIndex],-18}-- written successfully");
}
catch (Exception ex)
{
    Console.WriteLine($"\tFailed to write greeting: --{s_greetings[s_greetingIndex]}");
    Console.WriteLine(ex.Message);
    throw;
}

// Insert multiple rows using MutateRows()
// Build a MutateRowsRequest (contains table name and a collection of entries).
MutateRowsRequest request = new MutateRowsRequest
{
    TableNameAsTableName = tableName
};

s_mapToOriginalGreetingIndex = new List<int>();
while (++s_greetingIndex < s_greetings.Length)
{
    s_mapToOriginalGreetingIndex.Add(s_greetingIndex);
    // Build an entry for every greeting (consists of rowkey and a collection of mutations).
    string rowKey = rowKeyPrefix + s_greetingIndex;
    request.Entries.Add(Mutations.CreateEntry(rowKey, MutationBuilder()));
}

// Make the request to write multiple rows.
MutateRowsResponse response = bigtableClient.MutateRows(request);

// Check the status code of each entry to ensure that it was written successfully.
foreach (MutateRowsResponse.Types.Entry entry in response.Entries)
{
    s_greetingIndex = s_mapToOriginalGreetingIndex[(int)entry.Index];
    if (entry.Status.Code == 0)
    {
        Console.WriteLine($"\tGreeting:   -- {s_greetings[s_greetingIndex],-18}-- written successfully");
    }
    else
    {
        Console.WriteLine($"\tFailed to write greeting: --{s_greetings[s_greetingIndex]}");
        Console.WriteLine(entry.Status.Message);
    }
}

Mutation MutationBuilder() =>
    Mutations.SetCell(columnFamily, columnName, s_greetings[s_greetingIndex], new BigtableVersion(DateTime.UtcNow));

建立篩選器

讀取已寫入的資料前，請先建立篩選器，藉此限制 Bigtable 傳回的資料。即使資料表中含有符合垃圾回收資格但尚未刪除的較舊儲存格，篩選器仍會指示 Bigtable 僅傳回每個值的最新版本。

RowFilter filter = RowFilters.CellsPerRowLimit(1);

依資料列索引鍵讀取資料列

使用 ReadRow() 方法傳入您剛建立的篩選器，取得該資料列中每個值的一個版本。

// Read from the table.
Console.WriteLine("Read the first row");

int rowIndex = 0;

// Read a specific row. Apply a filter to return latest only cell value accross entire row.
Row rowRead = bigtableClient.ReadRow(
    tableName, rowKey: rowKeyPrefix + rowIndex, filter: filter);
Console.WriteLine(
    $"\tRow key: {rowRead.Key.ToStringUtf8()} " +
    $"  -- Value: {rowRead.Families[0].Columns[0].Cells[0].Value.ToStringUtf8(),-16} " +
    $"  -- Time Stamp: {rowRead.Families[0].Columns[0].Cells[0].TimestampMicros}");

掃描所有資料表資料列

呼叫 ReadRows() 方法並傳入篩選器，即可取得資料表中的所有資料列。您已傳入篩選器，因此 Bigtable 只會傳回每個值的一個版本。

Console.WriteLine("Read all rows using streaming");
// stream the content of the whole table. Apply a filter to return latest only cell values accross all rows.
ReadRowsStream responseRead = bigtableClient.ReadRows(tableName, filter: filter);

Task printRead = PrintReadRowsAsync();
printRead.Wait();

async Task PrintReadRowsAsync()
{
    var responseEnumerator = responseRead.GetAsyncEnumerator(default);
    while (await responseEnumerator.MoveNextAsync())
    {
        Row row = responseEnumerator.Current;
        Console.WriteLine(
            $"\tRow key: {row.Key.ToStringUtf8()} " +
            $"  -- Value: {row.Families[0].Columns[0].Cells[0].Value.ToStringUtf8(),-16} " +
            $"  -- Time Stamp: {row.Families[0].Columns[0].Cells[0].TimestampMicros}");
    }
}

刪除資料表

使用 DeleteTable() 方法刪除資料表。

// Clean up. Delete the table.
Console.WriteLine($"Delete table: {tableId}");

bigtableTableAdminClient.DeleteTable(name: tableName);
if (!TableExist(bigtableTableAdminClient))
{
    Console.WriteLine($"Table: {tableId} deleted successfully");
}

全面整合使用

以下是不含評論的完整程式碼範例。



using Google.Cloud.Bigtable.Admin.V2;
using Google.Cloud.Bigtable.Common.V2;
using Google.Cloud.Bigtable.V2;
using Grpc.Core;
using System;
using System.Collections.Generic;
using System.Threading.Tasks;

namespace GoogleCloudSamples.Bigtable
{
    public class HelloWorld
    {
        private const string projectId = "YOUR-PROJECT-ID";

        private const string instanceId = "YOUR-INSTANCE-ID";

        private const string tableId = "Hello-Bigtable";
        private const string columnFamily = "cf";
        private const string columnName = "greeting";
        private static readonly string[] s_greetings = { "Hello World!", "Hello Bigtable!", "Hello C#!" };
        private static List<int> s_mapToOriginalGreetingIndex;
        private const string rowKeyPrefix = "greeting";
        private static int s_greetingIndex;

        private static void DoHelloWorld()
        {
            try
            {
                BigtableTableAdminClient bigtableTableAdminClient = BigtableTableAdminClient.Create();

                BigtableClient bigtableClient = BigtableClient.Create();

                Console.WriteLine($"Create new table: {tableId} with column family: {columnFamily}, instance: {instanceId}");

                if (!TableExist(bigtableTableAdminClient))
                {
                    bigtableTableAdminClient.CreateTable(
                        new InstanceName(projectId, instanceId),
                        tableId,
                        new Table
                        {
                            Granularity = Table.Types.TimestampGranularity.Millis,
                            ColumnFamilies =
                            {
                                {
                                    columnFamily, new ColumnFamily
                                    {
                                        GcRule = new GcRule
                                        {
                                            MaxNumVersions = 1
                                        }
                                    }
                                }
                            }
                        });
                    Console.WriteLine(TableExist(bigtableTableAdminClient)
                        ? $"Table {tableId} created successfully\n"
                        : $"There was a problem creating a table {tableId}");
                }
                else
                {
                    Console.WriteLine($"Table: {tableId} already exists");
                }

                Google.Cloud.Bigtable.Common.V2.TableName tableName = new Google.Cloud.Bigtable.Common.V2.TableName(projectId, instanceId, tableId);


                       Note: This example uses sequential numeric IDs for simplicity, but
                       this can result in poor performance in a production application.
                       Since rows are stored in sorted order by key, sequential keys can
                       result in poor distribution of operations across nodes.

                       For more information about how to design a Bigtable schema for the
                       best performance, see the documentation:

                       https://cloud.google.com/bigtable/docs/schema-design */

                Console.WriteLine($"Write some greetings to the table {tableId}");

                s_greetingIndex = 0;
                try
                {
                    bigtableClient.MutateRow(tableName, rowKeyPrefix + s_greetingIndex, MutationBuilder());
                    Console.WriteLine($"\tGreeting:   -- {s_greetings[s_greetingIndex],-18}-- written successfully");
                }
                catch (Exception ex)
                {
                    Console.WriteLine($"\tFailed to write greeting: --{s_greetings[s_greetingIndex]}");
                    Console.WriteLine(ex.Message);
                    throw;
                }

                MutateRowsRequest request = new MutateRowsRequest
                {
                    TableNameAsTableName = tableName
                };

                s_mapToOriginalGreetingIndex = new List<int>();
                while (++s_greetingIndex < s_greetings.Length)
                {
                    s_mapToOriginalGreetingIndex.Add(s_greetingIndex);
                    string rowKey = rowKeyPrefix + s_greetingIndex;
                    request.Entries.Add(Mutations.CreateEntry(rowKey, MutationBuilder()));
                }

                MutateRowsResponse response = bigtableClient.MutateRows(request);

                foreach (MutateRowsResponse.Types.Entry entry in response.Entries)
                {
                    s_greetingIndex = s_mapToOriginalGreetingIndex[(int)entry.Index];
                    if (entry.Status.Code == 0)
                    {
                        Console.WriteLine($"\tGreeting:   -- {s_greetings[s_greetingIndex],-18}-- written successfully");
                    }
                    else
                    {
                        Console.WriteLine($"\tFailed to write greeting: --{s_greetings[s_greetingIndex]}");
                        Console.WriteLine(entry.Status.Message);
                    }
                }

                Mutation MutationBuilder() =>
                    Mutations.SetCell(columnFamily, columnName, s_greetings[s_greetingIndex], new BigtableVersion(DateTime.UtcNow));

                RowFilter filter = RowFilters.CellsPerRowLimit(1);

                Console.WriteLine("Read the first row");

                int rowIndex = 0;

                Row rowRead = bigtableClient.ReadRow(
                    tableName, rowKey: rowKeyPrefix + rowIndex, filter: filter);
                Console.WriteLine(
                    $"\tRow key: {rowRead.Key.ToStringUtf8()} " +
                    $"  -- Value: {rowRead.Families[0].Columns[0].Cells[0].Value.ToStringUtf8(),-16} " +
                    $"  -- Time Stamp: {rowRead.Families[0].Columns[0].Cells[0].TimestampMicros}");

                Console.WriteLine("Read all rows using streaming");
                ReadRowsStream responseRead = bigtableClient.ReadRows(tableName, filter: filter);

                Task printRead = PrintReadRowsAsync();
                printRead.Wait();

                async Task PrintReadRowsAsync()
                {
                    var responseEnumerator = responseRead.GetAsyncEnumerator(default);
                    while (await responseEnumerator.MoveNextAsync())
                    {
                        Row row = responseEnumerator.Current;
                        Console.WriteLine(
                            $"\tRow key: {row.Key.ToStringUtf8()} " +
                            $"  -- Value: {row.Families[0].Columns[0].Cells[0].Value.ToStringUtf8(),-16} " +
                            $"  -- Time Stamp: {row.Families[0].Columns[0].Cells[0].TimestampMicros}");
                    }
                }

                Console.WriteLine($"Delete table: {tableId}");

                bigtableTableAdminClient.DeleteTable(name: tableName);
                if (!TableExist(bigtableTableAdminClient))
                {
                    Console.WriteLine($"Table: {tableId} deleted successfully");
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine($"Exception while running HelloWorld: {ex.Message}");
            }
        }

        private static bool TableExist(BigtableTableAdminClient bigtableTableAdminClient)
        {
            GetTableRequest request = new GetTableRequest
            {
                TableName = new Google.Cloud.Bigtable.Common.V2.TableName(projectId, instanceId, tableId),
                View = Table.Types.View.NameOnly
            };
            try
            {
                var tables = bigtableTableAdminClient.GetTable(request);
                return true;
            }
            catch (RpcException ex)
            {
                if (ex.StatusCode == StatusCode.NotFound)
                {
                    return false;
                }

                throw;
            }
        }

        public static int Main(string[] args)
        {
            if (projectId == "YOUR-PROJECT" + "-ID")
            {
                Console.WriteLine("Edit HelloWorld.cs and replace YOUR-PROJECT-ID with your project ID.");
                return -1;
            }
            if (instanceId == "YOUR-INSTANCE" + "-ID")
            {
                Console.WriteLine("Edit HelloWorld.cs and replace YOUR-INSTANCE-ID with your instance ID.");
                return -1;
            }

            DoHelloWorld();
            return 0;
        }
    }
}