C# hello world

This code sample is a "hello world" application written in C#. The sample illustrates how to complete the following tasks:

  • Set up authentication
  • Connect to a Bigtable instance
  • Create a new table.
  • Write data to the table.
  • Read the data back.
  • Delete the table.

Set up authentication

To use the .NET samples on this page in a local development environment, install and initialize the gcloud CLI, and then set up Application Default Credentials with your user credentials.

  1. Install the Google Cloud CLI.

  2. If you're using an external identity provider (IdP), you must first sign in to the gcloud CLI with your federated identity.

  3. If you're using a local shell, then create local authentication credentials for your user account: 

    gcloud auth application-default login

    You don't need to do this if you're using Cloud Shell.

    If an authentication error is returned, and you are using an external identity provider (IdP), confirm that you have signed in to the gcloud CLI with your federated identity.

For more information, see Set up authentication for a local development environment.

Running the sample

This code communicates with Bigtable using the C# Admin API and C# Data API libraries in the Google Cloud Client Libraries for .NET.

To run this sample program, follow the .NET Bigtable Samples instructions on GitHub. Complete the Build and Run and Quick Start steps to create resources that you can use in your Hello World application. Make sure you edit the HelloWorld.cs file to add the names of the resources you create.

Using the Cloud Client Libraries with Bigtable

The sample application connects to Bigtable and demonstrates some simple operations.

Connecting to Bigtable

To get started, create two client objects that you can use to connect to Bigtable. The C# Admin APIs BigtableTableAdminClient helps you create and delete instances and tables. The C# Data APIs BigtableClient helps you read and write table data.

// 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();

Creating a table

Call the CreateTable() method in the BigtableTableAdminClient class to generate a Table object that stores the "hello world" greetings. The table has a single column family that retains one version of each value.

// 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");
}

Writing rows to a table

Use the string array s_greetings[], which contains three simple greetings, as a source of data to write to the table. First, write a single row to the table using MutateRow(). Then loop through the rest of the array to build a MutateRowsRequest object that contains an entry for each greeting. Make the request to write all the entries at once with MutateRows(). Then loop through the returned response to check the status code for each entry to make sure it was written successfully.

// 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.