Ruby 版 Hello World

本代码示例是一个在 Ruby 上运行的“hello world”应用，其中演示了如何完成以下任务：

• 设置身份验证
• 连接到 Bigtable 实例。
• 新建一个表。
• 将数据写入表中。
• 重新读取这些数据。
• 删除表。

设置身份验证

如需在本地开发环境中使用本页面上的 Ruby 示例，请安装并初始化 gcloud CLI，然后使用您的用户凭证设置应用默认凭证。

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. To initialize the gcloud CLI, run the following command:

   gcloud init

4. 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.

如需了解详情，请参阅 Set up authentication for a local development environment。 如需了解详情，请参阅身份验证文档中的为本地开发环境设置 ADC。

运行示例

此代码示例使用 Ruby 版 Google Cloud 客户端库的适用于 Bigtable 的 Ruby 客户端库软件包与 Bigtable 通信。

要运行此示例程序，请按照 GitHub 上的相应示例说明执行操作。

将 Cloud 客户端库与 Bigtable 搭配使用

示例应用会连接到 Bigtable 并演示一些简单操作。

需要客户端库

该示例需要使用 google/cloud/bigtable，其中提供了 Bigtable 模块。

require "google/cloud/bigtable"

连接到 Bigtable

建立您要在应用中使用的变量，并将“YOUR_PROJECT_ID”替换为有效 Google Cloud 项目的 ID。然后，创建一个新的 Bigtable 对象，您将使用此对象连接到 Bigtable。

# These variables are used in the sample code below.
# instance_id      = "my-instance"
# table_id         = "my-table"
# column_family    = "cf"
# column_qualifier = "greeting"

bigtable = Google::Cloud::Bigtable.new
table_client = bigtable.table_admin_client

创建表

检查您的表是否已存在。如果不存在，请调用 create_table() 方法来创建一个 Table 对象。该表有一个列族，其中保留了每个值的一个版本。

注意：彼此相关的列通常组合在一起形成一个列族。如需详细了解列族，请参阅 Bigtable 存储模型。

# This is the full resource name for the table. Use this name to make admin
# calls for the table, such as reading or deleting the resource.
table_name = table_client.table_path project: bigtable.project_id,
                                     instance: instance_id,
                                     table: table_id
begin
  # Attempt to get the table to see if it already exists
  table_client.get_table name: table_name
  puts "#{table_id} is already exists."
  exit 0
rescue Google::Cloud::NotFoundError
  # The table doesn't exist, so let's create it.
  # The following is the resource name for the table's instance.
  instance_name = table_client.instance_path project: bigtable.project_id,
                                             instance: instance_id
  # This is the configuration of the table's column families.
  table_config = {
    column_families: {
      column_family => {
        gc_rule: Google::Cloud::Bigtable::Admin::V2::GcRule.max_num_versions(1)
      }
    }
  }
  # Now call the API to create the table.
  table_client.create_table parent: instance_name,
                            table_id: table_id,
                            table: table_config
  puts "Table #{table_id} created."
end

将行写入表

接下来，使用由问候语组成的字符串数组来为表创建一些新行。对于每条问候语，使用表的 new_mutation_entry() 方法创建一个条目。然后，使用条目的 set_cell() 方法为该条目分配列族、列限定符、问候语和时间戳。最后，使用表的 mutate_row() 方法将该条目写入表中。

注意： 在本示例应用中，每次变更仅调用 set_Cell() 一次，但实际上每一次变更可对其调用最多 10000 次。

puts "Write some greetings to the table #{table_id}"
greetings = ["Hello World!", "Hello Bigtable!", "Hello Ruby!"]

# Get a table data object for the new table we created.
table = bigtable.table instance_id, table_id

# Insert rows one by one
# Note: To perform multiple mutation on multiple rows use `mutate_rows`.
greetings.each_with_index do |value, i|
  puts " Writing,  Row key: greeting#{i}, Value: #{value}"

  entry = table.new_mutation_entry "greeting#{i}"
  entry.set_cell(
    column_family,
    column_qualifier,
    value,
    timestamp: (Time.now.to_f * 1_000_000).round(-3)
  )

  table.mutate_row entry
end

创建过滤条件

在读取您写入的数据之前，请创建过滤条件，以限制 Bigtable 返回的数据。此过滤条件指示 Bigtable 仅返回每个值的最新版本，即使该表包含尚未被垃圾回收的旧版本。

# Only retrieve the most recent version of the cell.
filter = Google::Cloud::Bigtable::RowFilter.cells_per_column 1

按行键读取行

创建一个行对象，然后调用 read_row() 方法并传入过滤条件，以获取该行中每个值的一个版本。

puts "Reading a single row by row key"
row = table.read_row "greeting0", filter: filter
puts "Row key: #{row.key}, Value: #{row.cells[column_family].first.value}"

扫描所有表行

调用 read_rows() 方法并传入过滤条件，以获取表中的所有行。由于您传入了过滤条件，因此 Bigtable 仅会返回每个值的一个版本。

puts "Reading the entire table"
table.read_rows.each do |row|
  puts "Row key: #{row.key}, Value: #{row.cells[column_family].first.value}"
end

删除表

使用表的 delete() 方法删除表。

puts "Deleting the table #{table_id}"
# Call the admin API to delete the table given its full resource path.
table_client.delete_table name: table_name

综合应用

以下为不包含注释的完整代码示例。

# Copyright 2021 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

def hello_world instance_id, table_id, column_family, column_qualifier
  require "google/cloud/bigtable"

  # These variables are used in the sample code below.
  # instance_id      = "my-instance"
  # table_id         = "my-table"
  # column_family    = "cf"
  # column_qualifier = "greeting"

  bigtable = Google::Cloud::Bigtable.new
  table_client = bigtable.table_admin_client

  # This is the full resource name for the table. Use this name to make admin
  # calls for the table, such as reading or deleting the resource.
  table_name = table_client.table_path project: bigtable.project_id,
                                       instance: instance_id,
                                       table: table_id
  begin
    # Attempt to get the table to see if it already exists
    table_client.get_table name: table_name
    puts "#{table_id} is already exists."
    exit 0
  rescue Google::Cloud::NotFoundError
    # The table doesn't exist, so let's create it.
    # The following is the resource name for the table's instance.
    instance_name = table_client.instance_path project: bigtable.project_id,
                                               instance: instance_id
    # This is the configuration of the table's column families.
    table_config = {
      column_families: {
        column_family => {
          gc_rule: Google::Cloud::Bigtable::Admin::V2::GcRule.max_num_versions(1)
        }
      }
    }
    # Now call the API to create the table.
    table_client.create_table parent: instance_name,
                              table_id: table_id,
                              table: table_config
    puts "Table #{table_id} created."
  end

  puts "Write some greetings to the table #{table_id}"
  greetings = ["Hello World!", "Hello Bigtable!", "Hello Ruby!"]

  # Get a table data object for the new table we created.
  table = bigtable.table instance_id, table_id

  # Insert rows one by one
  # Note: To perform multiple mutation on multiple rows use `mutate_rows`.
  greetings.each_with_index do |value, i|
    puts " Writing,  Row key: greeting#{i}, Value: #{value}"

    entry = table.new_mutation_entry "greeting#{i}"
    entry.set_cell(
      column_family,
      column_qualifier,
      value,
      timestamp: (Time.now.to_f * 1_000_000).round(-3)
    )

    table.mutate_row entry
  end

  # Only retrieve the most recent version of the cell.
  filter = Google::Cloud::Bigtable::RowFilter.cells_per_column 1

  puts "Reading a single row by row key"
  row = table.read_row "greeting0", filter: filter
  puts "Row key: #{row.key}, Value: #{row.cells[column_family].first.value}"

  puts "Reading the entire table"
  table.read_rows.each do |row|
    puts "Row key: #{row.key}, Value: #{row.cells[column_family].first.value}"
  end

  puts "Deleting the table #{table_id}"
  # Call the admin API to delete the table given its full resource path.
  table_client.delete_table name: table_name
end