Ruby hello world

這個程式碼範例是在 Ruby 上執行的「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 Ruby 範例，請安裝並初始化 gcloud CLI，然後使用使用者憑證設定應用程式預設憑證。

  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.

詳情請參閱 Set up authentication for a local development environment。

執行範例

本程式碼範例使用 Ruby 適用的 Google Cloud 用戶端程式庫的 Bigtable Ruby 用戶端程式庫套件，與 Bigtable 進行通訊。

如要執行這個範例程式，請按照 GitHub 網頁上的說明操作。

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。

須使用用戶端程式庫

範例需要 google/cloud/bigtable，其中提供 Bigtable 模組。

require "google/cloud/bigtable"

連線至 Bigtable

建立要在應用程式中使用的變數，並將「YOUR_PROJECT_ID」替換為有效專案的 ID。 Google Cloud 然後建立新的 Bigtable 物件，用來連線至 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

建立資料表

檢查資料表是否已存在。如果沒有，請呼叫 create_table() 方法來建立 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。

# 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

將資料列寫入資料表

接著，使用問候語字串陣列為資料表建立幾個新的資料列。針對每則問候語，使用資料表的 new_mutation_entry() 方法建立項目。接著，使用項目的 set_cell() 方法，將資料欄系列、資料欄限定詞、問候語和時間戳記指派給項目。最後，使用資料表的 mutate_row() 方法，將該項目寫入資料表。

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

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。即使資料表中含有每個值未經過垃圾收集處理的較舊版本，篩選器仍能指示 Bigtable 僅傳回每個值的最新版本。

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

依資料列索引鍵讀取資料列

建立資料列物件，然後呼叫 read_row() 方法並傳入篩選器，即可取得該資料列中每個資料值的一個版本。

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}"

掃描所有資料表資料列

呼叫 read_rows() 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。

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

刪除資料表

運用資料表的 delete() 方法來刪除資料表。

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

全面整合使用

以下是不含評論的完整程式碼範例。

# 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