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# 使用适用于 Ruby 的 SDK 的 DynamoDB 示例
以下代码示例向您展示了如何在 DynamoDB 中使用来执行操作和实现常见场景。 适用于 Ruby 的 AWS SDK
*基本功能*是向您展示如何在服务中执行基本操作的代码示例。
*操作*是大型程序的代码摘录，必须在上下文中运行。您可以通过操作了解如何调用单个服务函数，还可以通过函数相关场景的上下文查看操作。
*场景*是向您演示如何通过在一个服务中调用多个函数或与其他 AWS 服务结合来完成特定任务的代码示例。
每个示例都包含一个指向完整源代码的链接，您可以从中找到有关如何在上下文中设置和运行代码的说明。
**Topics**
+ [开始使用](#get_started)
+ [基本功能](#basics)
+ [操作](#actions)
+ [场景](#scenarios)
+ [无服务器示例](#serverless_examples)
## 开始使用
### 开始使用 DynamoDB
以下代码示例显示如何开始使用 DynamoDB。
**适用于 Ruby 的 SDK**
还有更多相关信息 GitHub。在 [AWS 代码示例存储库](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/ruby/example_code/dynamodb#code-examples)中查找完整示例，了解如何进行设置和运行。
```
require 'aws-sdk-dynamodb'
require 'logger'
# DynamoDBManager is a class responsible for managing DynamoDB operations
# such as listing all tables in the current AWS account.
class DynamoDBManager
def initialize(client)
@client = client
@logger = Logger.new($stdout)
end
# Lists and prints all DynamoDB tables in the current AWS account.
def list_tables
@logger.info('Here are the DynamoDB tables in your account:')
paginator = @client.list_tables(limit: 10)
table_names = []
paginator.each_page do |page|
page.table_names.each do |table_name|
@logger.info("- #{table_name}")
table_names << table_name
end
end
if table_names.empty?
@logger.info("You don't have any DynamoDB tables in your account.")
else
@logger.info("\nFound #{table_names.length} tables.")
end
end
end
if $PROGRAM_NAME == __FILE__
dynamodb_client = Aws::DynamoDB::Client.new
manager = DynamoDBManager.new(dynamodb_client)
manager.list_tables
end
```
+ 有关 API 的详细信息，请参阅 *适用于 Ruby 的 AWS SDK API 参考[ListTables](https://docs.aws.amazon.com/goto/SdkForRubyV3/dynamodb-2012-08-10/ListTables)*中的。
## 基本功能
### 了解基本功能
以下代码示例展示了如何：
+ 创建可保存电影数据的表。
+ 在表中加入单一电影，获取并更新此电影。
+ 向 JSON 示例文件的表中写入电影数据。
+ 查询在给定年份发行的电影。
+ 扫描在年份范围内发行的电影。
+ 删除表中的电影后再删除表。
**适用于 Ruby 的 SDK**
还有更多相关信息 GitHub。在 [AWS 代码示例存储库](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/ruby/example_code/dynamodb#code-examples)中查找完整示例，了解如何进行设置和运行。
创建封装 DynamoDB 表的类。
```
# Creates an Amazon DynamoDB table that can be used to store movie data.
# The table uses the release year of the movie as the partition key and the
# title as the sort key.
#
# @param table_name [String] The name of the table to create.
# @return [Aws::DynamoDB::Table] The newly created table.
def create_table(table_name)
@table = @dynamo_resource.create_table(
table_name: table_name,
key_schema: [
{ attribute_name: 'year', key_type: 'HASH' }, # Partition key
{ attribute_name: 'title', key_type: 'RANGE' } # Sort key
],
attribute_definitions: [
{ attribute_name: 'year', attribute_type: 'N' },
{ attribute_name: 'title', attribute_type: 'S' }
],
billing_mode: 'PAY_PER_REQUEST'
)
@dynamo_resource.client.wait_until(:table_exists, table_name: table_name)
@table
rescue Aws::DynamoDB::Errors::ServiceError => e
@logger.error("Failed create table #{table_name}:\n#{e.code}: #{e.message}")
raise
end
```
创建帮助函数以下载并提取示例 JSON 文件。
```
# Gets sample movie data, either from a local file or by first downloading it from
# the Amazon DynamoDB Developer Guide.
#
# @param movie_file_name [String] The local file name where the movie data is stored in JSON format.
# @return [Hash] The movie data as a Hash.
def fetch_movie_data(movie_file_name)
if !File.file?(movie_file_name)
@logger.debug("Downloading #{movie_file_name}...")
movie_content = URI.open(
'https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/samples/moviedata.zip'
)
movie_json = ''
Zip::File.open_buffer(movie_content) do |zip|
zip.each do |entry|
movie_json = entry.get_input_stream.read
end
end
else
movie_json = File.read(movie_file_name)
end
movie_data = JSON.parse(movie_json)
# The sample file lists over 4000 movies. This returns only the first 250.
movie_data.slice(0, 250)
rescue StandardError => e
puts("Failure downloading movie data:\n#{e}")
raise
end
```
运行交互式场景以创建表并对其执行操作。
```
table_name = "doc-example-table-movies-#{rand(10**4)}"
scaffold = Scaffold.new(table_name)
dynamodb_wrapper = DynamoDBBasics.new(table_name)
new_step(1, 'Create a new DynamoDB table if none already exists.')
unless scaffold.exists?(table_name)
puts("\nNo such table: #{table_name}. Creating it...")
scaffold.create_table(table_name)
print "Done!\n".green
end
new_step(2, 'Add a new record to the DynamoDB table.')
my_movie = {}
my_movie[:title] = CLI::UI::Prompt.ask('Enter the title of a movie to add to the table. E.g. The Matrix')
my_movie[:year] = CLI::UI::Prompt.ask('What year was it released? E.g. 1989').to_i
my_movie[:rating] = CLI::UI::Prompt.ask('On a scale of 1 - 10, how do you rate it? E.g. 7').to_i
my_movie[:plot] = CLI::UI::Prompt.ask('Enter a brief summary of the plot. E.g. A man awakens to a new reality.')
dynamodb_wrapper.add_item(my_movie)
puts("\nNew record added:")
puts JSON.pretty_generate(my_movie).green
print "Done!\n".green
new_step(3, 'Update a record in the DynamoDB table.')
my_movie[:rating] = CLI::UI::Prompt.ask("Let's update the movie you added with a new rating, e.g. 3:").to_i
response = dynamodb_wrapper.update_item(my_movie)
puts("Updated '#{my_movie[:title]}' with new attributes:")
puts JSON.pretty_generate(response).green
print "Done!\n".green
new_step(4, 'Get a record from the DynamoDB table.')
puts("Searching for #{my_movie[:title]} (#{my_movie[:year]})...")
response = dynamodb_wrapper.get_item(my_movie[:title], my_movie[:year])
puts JSON.pretty_generate(response).green
print "Done!\n".green
new_step(5, 'Write a batch of items into the DynamoDB table.')
download_file = 'moviedata.json'
puts("Downloading movie database to #{download_file}...")
movie_data = scaffold.fetch_movie_data(download_file)
puts("Writing movie data from #{download_file} into your table...")
scaffold.write_batch(movie_data)
puts("Records added: #{movie_data.length}.")
print "Done!\n".green
new_step(5, 'Query for a batch of items by key.')
loop do
release_year = CLI::UI::Prompt.ask('Enter a year between 1972 and 2018, e.g. 1999:').to_i
results = dynamodb_wrapper.query_items(release_year)
if results.any?
puts("There were #{results.length} movies released in #{release_year}:")
results.each do |movie|
print "\t #{movie['title']}".green
end
break
else
continue = CLI::UI::Prompt.ask("Found no movies released in #{release_year}! Try another year? (y/n)")
break unless continue.eql?('y')
end
end
print "\nDone!\n".green
new_step(6, 'Scan for a batch of items using a filter expression.')
years = {}
years[:start] = CLI::UI::Prompt.ask('Enter a starting year between 1972 and 2018:')
years[:end] = CLI::UI::Prompt.ask('Enter an ending year between 1972 and 2018:')
releases = dynamodb_wrapper.scan_items(years)
if !releases.empty?
puts("Found #{releases.length} movies.")
count = Question.ask(
'How many do you want to see? ', method(:is_int), in_range(1, releases.length)
)
puts("Here are your #{count} movies:")
releases.take(count).each do |release|
puts("\t#{release['title']}")
end
else
puts("I don't know about any movies released between #{years[:start]} "\
"and #{years[:end]}.")
end
print "\nDone!\n".green
new_step(7, 'Delete an item from the DynamoDB table.')
answer = CLI::UI::Prompt.ask("Do you want to remove '#{my_movie[:title]}'? (y/n) ")
if answer.eql?('y')
dynamodb_wrapper.delete_item(my_movie[:title], my_movie[:year])
puts("Removed '#{my_movie[:title]}' from the table.")
print "\nDone!\n".green
end
new_step(8, 'Delete the DynamoDB table.')
answer = CLI::UI::Prompt.ask('Delete the table? (y/n)')
if answer.eql?('y')
scaffold.delete_table
puts("Deleted #{table_name}.")
else
puts("Don't forget to delete the table when you're done!")
end
print "\nThanks for watching!\n".green
rescue Aws::Errors::ServiceError
puts('Something went wrong with the demo.')
rescue Errno::ENOENT
true
end
```
+ 有关 API 详细信息，请参阅《适用于 Ruby 的 AWS SDK API 参考》**中的以下主题。
+ [BatchWriteItem](https://docs.aws.amazon.com/goto/SdkForRubyV3/dynamodb-2012-08-10/BatchWriteItem)
+ [CreateTable](https://docs.aws.amazon.com/goto/SdkForRubyV3/dynamodb-2012-08-10/CreateTable)
+ [DeleteItem](https://docs.aws.amazon.com/goto/SdkForRubyV3/dynamodb-2012-08-10/DeleteItem)
+ [DeleteTable](https://docs.aws.amazon.com/goto/SdkForRubyV3/dynamodb-2012-08-10/DeleteTable)
+ [DescribeTable](https://docs.aws.amazon.com/goto/SdkForRubyV3/dynamodb-2012-08-10/DescribeTable)
+ [GetItem](https://docs.aws.amazon.com/goto/SdkForRubyV3/dynamodb-2012-08-10/GetItem)
+ [PutItem](https://docs.aws.amazon.com/goto/SdkForRubyV3/dynamodb-2012-08-10/PutItem)
+ [Query](https://docs.aws.amazon.com/goto/SdkForRubyV3/dynamodb-2012-08-10/Query)
+ [Scan](https://docs.aws.amazon.com/goto/SdkForRubyV3/dynamodb-2012-08-10/Scan)
+ [UpdateItem](https://docs.aws.amazon.com/goto/SdkForRubyV3/dynamodb-2012-08-10/UpdateItem)
## 操作
### `BatchExecuteStatement`
以下代码示例演示了如何使用 `BatchExecuteStatement`。
**适用于 Ruby 的 SDK**
还有更多相关信息 GitHub。在 [AWS 代码示例存储库](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/ruby/example_code/dynamodb#code-examples)中查找完整示例，了解如何进行设置和运行。
使用 PartiQL 读取一批项目。
```
class DynamoDBPartiQLBatch
attr_reader :dynamo_resource, :table
def initialize(table_name)
client = Aws::DynamoDB::Client.new(region: 'us-east-1')
@dynamodb = Aws::DynamoDB::Resource.new(client: client)
@table = @dynamodb.table(table_name)
end
# Selects a batch of items from a table using PartiQL
#
# @param batch_titles [Array] Collection of movie titles
# @return [Aws::DynamoDB::Types::BatchExecuteStatementOutput]
def batch_execute_select(batch_titles)
request_items = batch_titles.map do |title, year|
{
statement: "SELECT * FROM \"#{@table.name}\" WHERE title=? and year=?",
parameters: [title, year]
}
end
@dynamodb.client.batch_execute_statement({ statements: request_items })
end
```
使用 PartiQL 删除一批项目。
```
class DynamoDBPartiQLBatch
attr_reader :dynamo_resource, :table
def initialize(table_name)
client = Aws::DynamoDB::Client.new(region: 'us-east-1')
@dynamodb = Aws::DynamoDB::Resource.new(client: client)
@table = @dynamodb.table(table_name)
end
# Deletes a batch of items from a table using PartiQL
#
# @param batch_titles [Array] Collection of movie titles
# @return [Aws::DynamoDB::Types::BatchExecuteStatementOutput]
def batch_execute_write(batch_titles)
request_items = batch_titles.map do |title, year|
{
statement: "DELETE FROM \"#{@table.name}\" WHERE title=? and year=?",
parameters: [title, year]
}
end
@dynamodb.client.batch_execute_statement({ statements: request_items })
end
```
+ 有关 API 的详细信息，请参阅 *适用于 Ruby 的 AWS SDK API 参考[BatchExecuteStatement](https://docs.aws.amazon.com/goto/SdkForRubyV3/dynamodb-2012-08-10/BatchExecuteStatement)*中的。
### `BatchWriteItem`
以下代码示例演示了如何使用 `BatchWriteItem`。
**适用于 Ruby 的 SDK**
还有更多相关信息 GitHub。在 [AWS 代码示例存储库](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/ruby/example_code/dynamodb#code-examples)中查找完整示例，了解如何进行设置和运行。
```
class DynamoDBBasics
attr_reader :dynamo_resource, :table
def initialize(table_name)
client = Aws::DynamoDB::Client.new(region: 'us-east-1')
@dynamo_resource = Aws::DynamoDB::Resource.new(client: client)
@table = @dynamo_resource.table(table_name)
end
# Fills an Amazon DynamoDB table with the specified data. Items are sent in
# batches of 25 until all items are written.
#
# @param movies [Enumerable] The data to put in the table. Each item must contain at least
# the keys required by the schema that was specified when the
# table was created.
def write_batch(movies)
index = 0
slice_size = 25
while index < movies.length
movie_items = []
movies[index, slice_size].each do |movie|
movie_items.append({ put_request: { item: movie } })
end
@dynamo_resource.client.batch_write_item({ request_items: { @table.name => movie_items } })
index += slice_size
end
rescue Aws::DynamoDB::Errors::ServiceError => e
puts(
"Couldn't load data into table #{@table.name}. Here's why:"
)
puts("\t#{e.code}: #{e.message}")
raise
end
```
+ 有关 API 的详细信息，请参阅 *适用于 Ruby 的 AWS SDK API 参考[BatchWriteItem](https://docs.aws.amazon.com/goto/SdkForRubyV3/dynamodb-2012-08-10/BatchWriteItem)*中的。
### `CreateTable`
以下代码示例演示了如何使用 `CreateTable`。
**适用于 Ruby 的 SDK**
还有更多相关信息 GitHub。在 [AWS 代码示例存储库](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/ruby/example_code/dynamodb#code-examples)中查找完整示例，了解如何进行设置和运行。
```
# Encapsulates an Amazon DynamoDB table of movie data.
class Scaffold
attr_reader :dynamo_resource, :table_name, :table
def initialize(table_name)
client = Aws::DynamoDB::Client.new(region: 'us-east-1')
@dynamo_resource = Aws::DynamoDB::Resource.new(client: client)
@table_name = table_name
@table = nil
@logger = Logger.new($stdout)
@logger.level = Logger::DEBUG
end
# Creates an Amazon DynamoDB table that can be used to store movie data.
# The table uses the release year of the movie as the partition key and the
# title as the sort key.
#
# @param table_name [String] The name of the table to create.
# @return [Aws::DynamoDB::Table] The newly created table.
def create_table(table_name)
@table = @dynamo_resource.create_table(
table_name: table_name,
key_schema: [
{ attribute_name: 'year', key_type: 'HASH' }, # Partition key
{ attribute_name: 'title', key_type: 'RANGE' } # Sort key
],
attribute_definitions: [
{ attribute_name: 'year', attribute_type: 'N' },
{ attribute_name: 'title', attribute_type: 'S' }
],
billing_mode: 'PAY_PER_REQUEST'
)
@dynamo_resource.client.wait_until(:table_exists, table_name: table_name)
@table
rescue Aws::DynamoDB::Errors::ServiceError => e
@logger.error("Failed create table #{table_name}:\n#{e.code}: #{e.message}")
raise
end
```
+ 有关 API 的详细信息，请参阅 *适用于 Ruby 的 AWS SDK API 参考[CreateTable](https://docs.aws.amazon.com/goto/SdkForRubyV3/dynamodb-2012-08-10/CreateTable)*中的。
### `DeleteItem`
以下代码示例演示了如何使用 `DeleteItem`。
**适用于 Ruby 的 SDK**
还有更多相关信息 GitHub。在 [AWS 代码示例存储库](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/ruby/example_code/dynamodb#code-examples)中查找完整示例，了解如何进行设置和运行。
```
class DynamoDBBasics
attr_reader :dynamo_resource, :table
def initialize(table_name)
client = Aws::DynamoDB::Client.new(region: 'us-east-1')
@dynamo_resource = Aws::DynamoDB::Resource.new(client: client)
@table = @dynamo_resource.table(table_name)
end
# Deletes a movie from the table.
#
# @param title [String] The title of the movie to delete.
# @param year [Integer] The release year of the movie to delete.
def delete_item(title, year)
@table.delete_item(key: { 'year' => year, 'title' => title })
rescue Aws::DynamoDB::Errors::ServiceError => e
puts("Couldn't delete movie #{title}. Here's why:")
puts("\t#{e.code}: #{e.message}")
raise
end
```
+ 有关 API 的详细信息，请参阅 *适用于 Ruby 的 AWS SDK API 参考[DeleteItem](https://docs.aws.amazon.com/goto/SdkForRubyV3/dynamodb-2012-08-10/DeleteItem)*中的。
### `DeleteTable`
以下代码示例演示了如何使用 `DeleteTable`。
**适用于 Ruby 的 SDK**
还有更多相关信息 GitHub。在 [AWS 代码示例存储库](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/ruby/example_code/dynamodb#code-examples)中查找完整示例，了解如何进行设置和运行。
```
# Encapsulates an Amazon DynamoDB table of movie data.
class Scaffold
attr_reader :dynamo_resource, :table_name, :table
def initialize(table_name)
client = Aws::DynamoDB::Client.new(region: 'us-east-1')
@dynamo_resource = Aws::DynamoDB::Resource.new(client: client)
@table_name = table_name
@table = nil
@logger = Logger.new($stdout)
@logger.level = Logger::DEBUG
end
# Deletes the table.
def delete_table
@table.delete
@table = nil
rescue Aws::DynamoDB::Errors::ServiceError => e
puts("Couldn't delete table. Here's why:")
puts("\t#{e.code}: #{e.message}")
raise
end
```
+ 有关 API 的详细信息，请参阅 *适用于 Ruby 的 AWS SDK API 参考[DeleteTable](https://docs.aws.amazon.com/goto/SdkForRubyV3/dynamodb-2012-08-10/DeleteTable)*中的。
### `DescribeTable`
以下代码示例演示了如何使用 `DescribeTable`。
**适用于 Ruby 的 SDK**
还有更多相关信息 GitHub。在 [AWS 代码示例存储库](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/ruby/example_code/dynamodb#code-examples)中查找完整示例，了解如何进行设置和运行。
```
# Encapsulates an Amazon DynamoDB table of movie data.
class Scaffold
attr_reader :dynamo_resource, :table_name, :table
def initialize(table_name)
client = Aws::DynamoDB::Client.new(region: 'us-east-1')
@dynamo_resource = Aws::DynamoDB::Resource.new(client: client)
@table_name = table_name
@table = nil
@logger = Logger.new($stdout)
@logger.level = Logger::DEBUG
end
# Determines whether a table exists. As a side effect, stores the table in
# a member variable.
#
# @param table_name [String] The name of the table to check.
# @return [Boolean] True when the table exists; otherwise, False.
def exists?(table_name)
@dynamo_resource.client.describe_table(table_name: table_name)
@logger.debug("Table #{table_name} exists")
rescue Aws::DynamoDB::Errors::ResourceNotFoundException
@logger.debug("Table #{table_name} doesn't exist")
false
rescue Aws::DynamoDB::Errors::ServiceError => e
puts("Couldn't check for existence of #{table_name}:\n")
puts("\t#{e.code}: #{e.message}")
raise
end
```
+ 有关 API 的详细信息，请参阅 *适用于 Ruby 的 AWS SDK API 参考[DescribeTable](https://docs.aws.amazon.com/goto/SdkForRubyV3/dynamodb-2012-08-10/DescribeTable)*中的。
### `ExecuteStatement`
以下代码示例演示了如何使用 `ExecuteStatement`。
**适用于 Ruby 的 SDK**
还有更多相关信息 GitHub。在 [AWS 代码示例存储库](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/ruby/example_code/dynamodb#code-examples)中查找完整示例，了解如何进行设置和运行。
使用 PartiQL 选择单个项目。
```
class DynamoDBPartiQLSingle
attr_reader :dynamo_resource, :table
def initialize(table_name)
client = Aws::DynamoDB::Client.new(region: 'us-east-1')
@dynamodb = Aws::DynamoDB::Resource.new(client: client)
@table = @dynamodb.table(table_name)
end
# Gets a single record from a table using PartiQL.
# Note: To perform more fine-grained selects,
# use the Client.query instance method instead.
#
# @param title [String] The title of the movie to search.
# @return [Aws::DynamoDB::Types::ExecuteStatementOutput]
def select_item_by_title(title)
request = {
statement: "SELECT * FROM \"#{@table.name}\" WHERE title=?",
parameters: [title]
}
@dynamodb.client.execute_statement(request)
end
```
使用 PartiQL 更新单个项目。
```
class DynamoDBPartiQLSingle
attr_reader :dynamo_resource, :table
def initialize(table_name)
client = Aws::DynamoDB::Client.new(region: 'us-east-1')
@dynamodb = Aws::DynamoDB::Resource.new(client: client)
@table = @dynamodb.table(table_name)
end
# Updates a single record from a table using PartiQL.
#
# @param title [String] The title of the movie to update.
# @param year [Integer] The year the movie was released.
# @param rating [Float] The new rating to assign the title.
# @return [Aws::DynamoDB::Types::ExecuteStatementOutput]
def update_rating_by_title(title, year, rating)
request = {
statement: "UPDATE \"#{@table.name}\" SET info.rating=? WHERE title=? and year=?",
parameters: [{ "N": rating }, title, year]
}
@dynamodb.client.execute_statement(request)
end
```
使用 PartiQL 添加单个项目。
```
class DynamoDBPartiQLSingle
attr_reader :dynamo_resource, :table
def initialize(table_name)
client = Aws::DynamoDB::Client.new(region: 'us-east-1')
@dynamodb = Aws::DynamoDB::Resource.new(client: client)
@table = @dynamodb.table(table_name)
end
# Adds a single record to a table using PartiQL.
#
# @param title [String] The title of the movie to update.
# @param year [Integer] The year the movie was released.
# @param plot [String] The plot of the movie.
# @param rating [Float] The new rating to assign the title.
# @return [Aws::DynamoDB::Types::ExecuteStatementOutput]
def insert_item(title, year, plot, rating)
request = {
statement: "INSERT INTO \"#{@table.name}\" VALUE {'title': ?, 'year': ?, 'info': ?}",
parameters: [title, year, { 'plot': plot, 'rating': rating }]
}
@dynamodb.client.execute_statement(request)
end
```
使用 PartiQL 删除单个项目。
```
class DynamoDBPartiQLSingle
attr_reader :dynamo_resource, :table
def initialize(table_name)
client = Aws::DynamoDB::Client.new(region: 'us-east-1')
@dynamodb = Aws::DynamoDB::Resource.new(client: client)
@table = @dynamodb.table(table_name)
end
# Deletes a single record from a table using PartiQL.
#
# @param title [String] The title of the movie to update.
# @param year [Integer] The year the movie was released.
# @return [Aws::DynamoDB::Types::ExecuteStatementOutput]
def delete_item_by_title(title, year)
request = {
statement: "DELETE FROM \"#{@table.name}\" WHERE title=? and year=?",
parameters: [title, year]
}
@dynamodb.client.execute_statement(request)
end
```
+ 有关 API 的详细信息，请参阅 *适用于 Ruby 的 AWS SDK API 参考[ExecuteStatement](https://docs.aws.amazon.com/goto/SdkForRubyV3/dynamodb-2012-08-10/ExecuteStatement)*中的。
### `GetItem`
以下代码示例演示了如何使用 `GetItem`。
**适用于 Ruby 的 SDK**
还有更多相关信息 GitHub。在 [AWS 代码示例存储库](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/ruby/example_code/dynamodb#code-examples)中查找完整示例，了解如何进行设置和运行。
```
class DynamoDBBasics
attr_reader :dynamo_resource, :table
def initialize(table_name)
client = Aws::DynamoDB::Client.new(region: 'us-east-1')
@dynamo_resource = Aws::DynamoDB::Resource.new(client: client)
@table = @dynamo_resource.table(table_name)
end
# Gets movie data from the table for a specific movie.
#
# @param title [String] The title of the movie.
# @param year [Integer] The release year of the movie.
# @return [Hash] The data about the requested movie.
def get_item(title, year)
@table.get_item(key: { 'year' => year, 'title' => title })
rescue Aws::DynamoDB::Errors::ServiceError => e
puts("Couldn't get movie #{title} (#{year}) from table #{@table.name}:\n")
puts("\t#{e.code}: #{e.message}")
raise
end
```
+ 有关 API 的详细信息，请参阅 *适用于 Ruby 的 AWS SDK API 参考[GetItem](https://docs.aws.amazon.com/goto/SdkForRubyV3/dynamodb-2012-08-10/GetItem)*中的。
### `ListTables`
以下代码示例演示了如何使用 `ListTables`。
**适用于 Ruby 的 SDK**
还有更多相关信息 GitHub。在 [AWS 代码示例存储库](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/python/example_code/dynamodb#code-examples)中查找完整示例，了解如何进行设置和运行。
确定表是否存在。
```
# Encapsulates an Amazon DynamoDB table of movie data.
class Scaffold
attr_reader :dynamo_resource, :table_name, :table
def initialize(table_name)
client = Aws::DynamoDB::Client.new(region: 'us-east-1')
@dynamo_resource = Aws::DynamoDB::Resource.new(client: client)
@table_name = table_name
@table = nil
@logger = Logger.new($stdout)
@logger.level = Logger::DEBUG
end
# Determines whether a table exists. As a side effect, stores the table in
# a member variable.
#
# @param table_name [String] The name of the table to check.
# @return [Boolean] True when the table exists; otherwise, False.
def exists?(table_name)
@dynamo_resource.client.describe_table(table_name: table_name)
@logger.debug("Table #{table_name} exists")
rescue Aws::DynamoDB::Errors::ResourceNotFoundException
@logger.debug("Table #{table_name} doesn't exist")
false
rescue Aws::DynamoDB::Errors::ServiceError => e
puts("Couldn't check for existence of #{table_name}:\n")
puts("\t#{e.code}: #{e.message}")
raise
end
```
+ 有关 API 的详细信息，请参阅 *适用于 Ruby 的 AWS SDK API 参考[ListTables](https://docs.aws.amazon.com/goto/SdkForRubyV3/dynamodb-2012-08-10/ListTables)*中的。
### `PutItem`
以下代码示例演示了如何使用 `PutItem`。
**适用于 Ruby 的 SDK**
还有更多相关信息 GitHub。在 [AWS 代码示例存储库](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/ruby/example_code/dynamodb#code-examples)中查找完整示例，了解如何进行设置和运行。
```
class DynamoDBBasics
attr_reader :dynamo_resource, :table
def initialize(table_name)
client = Aws::DynamoDB::Client.new(region: 'us-east-1')
@dynamo_resource = Aws::DynamoDB::Resource.new(client: client)
@table = @dynamo_resource.table(table_name)
end
# Adds a movie to the table.
#
# @param movie [Hash] The title, year, plot, and rating of the movie.
def add_item(movie)
@table.put_item(
item: {
'year' => movie[:year],
'title' => movie[:title],
'info' => { 'plot' => movie[:plot], 'rating' => movie[:rating] }
}
)
rescue Aws::DynamoDB::Errors::ServiceError => e
puts("Couldn't add movie #{title} to table #{@table.name}. Here's why:")
puts("\t#{e.code}: #{e.message}")
raise
end
```
+ 有关 API 的详细信息，请参阅 *适用于 Ruby 的 AWS SDK API 参考[PutItem](https://docs.aws.amazon.com/goto/SdkForRubyV3/dynamodb-2012-08-10/PutItem)*中的。
### `Query`
以下代码示例演示了如何使用 `Query`。
**适用于 Ruby 的 SDK**
还有更多相关信息 GitHub。在 [AWS 代码示例存储库](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/ruby/example_code/dynamodb#code-examples) 中查找完整示例，了解如何进行设置和运行。
```
class DynamoDBBasics
attr_reader :dynamo_resource, :table
def initialize(table_name)
client = Aws::DynamoDB::Client.new(region: 'us-east-1')
@dynamo_resource = Aws::DynamoDB::Resource.new(client: client)
@table = @dynamo_resource.table(table_name)
end
# Queries for movies that were released in the specified year.
#
# @param year [Integer] The year to query.
# @return [Array] The list of movies that were released in the specified year.
def query_items(year)
response = @table.query(
key_condition_expression: '#yr = :year',
expression_attribute_names: { '#yr' => 'year' },
expression_attribute_values: { ':year' => year }
)
rescue Aws::DynamoDB::Errors::ServiceError => e
puts("Couldn't query for movies released in #{year}. Here's why:")
puts("\t#{e.code}: #{e.message}")
raise
else
response.items
end
```
+ 有关 API 详细信息，请参阅《适用于 Ruby 的 AWS SDK API Reference》**中的 [Query](https://docs.aws.amazon.com/goto/SdkForRubyV3/dynamodb-2012-08-10/Query)。
### `Scan`
以下代码示例演示了如何使用 `Scan`。
**适用于 Ruby 的 SDK**
还有更多相关信息 GitHub。在 [AWS 代码示例存储库](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/ruby/example_code/dynamodb#code-examples)中查找完整示例，了解如何进行设置和运行。
```
class DynamoDBBasics
attr_reader :dynamo_resource, :table
def initialize(table_name)
client = Aws::DynamoDB::Client.new(region: 'us-east-1')
@dynamo_resource = Aws::DynamoDB::Resource.new(client: client)
@table = @dynamo_resource.table(table_name)
end
# Scans for movies that were released in a range of years.
# Uses a projection expression to return a subset of data for each movie.
#
# @param year_range [Hash] The range of years to retrieve.
# @return [Array] The list of movies released in the specified years.
def scan_items(year_range)
movies = []
scan_hash = {
filter_expression: '#yr between :start_yr and :end_yr',
projection_expression: '#yr, title, info.rating',
expression_attribute_names: { '#yr' => 'year' },
expression_attribute_values: {
':start_yr' => year_range[:start], ':end_yr' => year_range[:end]
}
}
done = false
start_key = nil
until done
scan_hash[:exclusive_start_key] = start_key unless start_key.nil?
response = @table.scan(scan_hash)
movies.concat(response.items) unless response.items.empty?
start_key = response.last_evaluated_key
done = start_key.nil?
end
rescue Aws::DynamoDB::Errors::ServiceError => e
puts("Couldn't scan for movies. Here's why:")
puts("\t#{e.code}: #{e.message}")
raise
else
movies
end
```
+ 有关 API 详细信息，请参阅《适用于 Ruby 的 AWS SDK API Reference》**中的 [Scan](https://docs.aws.amazon.com/goto/SdkForRubyV3/dynamodb-2012-08-10/Scan)。
### `UpdateItem`
以下代码示例演示了如何使用 `UpdateItem`。
**适用于 Ruby 的 SDK**
还有更多相关信息 GitHub。在 [AWS 代码示例存储库](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/ruby/example_code/dynamodb#code-examples)中查找完整示例，了解如何进行设置和运行。
```
class DynamoDBBasics
attr_reader :dynamo_resource, :table
def initialize(table_name)
client = Aws::DynamoDB::Client.new(region: 'us-east-1')
@dynamo_resource = Aws::DynamoDB::Resource.new(client: client)
@table = @dynamo_resource.table(table_name)
end
# Updates rating and plot data for a movie in the table.
#
# @param movie [Hash] The title, year, plot, rating of the movie.
def update_item(movie)
response = @table.update_item(
key: { 'year' => movie[:year], 'title' => movie[:title] },
update_expression: 'set info.rating=:r',
expression_attribute_values: { ':r' => movie[:rating] },
return_values: 'UPDATED_NEW'
)
rescue Aws::DynamoDB::Errors::ServiceError => e
puts("Couldn't update movie #{movie[:title]} (#{movie[:year]}) in table #{@table.name}\n")
puts("\t#{e.code}: #{e.message}")
raise
else
response.attributes
end
```
+ 有关 API 的详细信息，请参阅 *适用于 Ruby 的 AWS SDK API 参考[UpdateItem](https://docs.aws.amazon.com/goto/SdkForRubyV3/dynamodb-2012-08-10/UpdateItem)*中的。
## 场景
### 使用批量 PartiQL 语句查询表
以下代码示例展示了如何：
+ 通过运行多个 SELECT 语句来获取一批项目。
+ 通过运行多个 INSERT 语句来添加一批项目。
+ 通过运行多个 UPDATE 语句来更新一批项目。
+ 通过运行多个 DELETE 语句来删除一批项目。
**适用于 Ruby 的 SDK**
还有更多相关信息 GitHub。在 [AWS 代码示例存储库](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/ruby/example_code/dynamodb#code-examples)中查找完整示例，了解如何进行设置和运行。
运行创建表并运行批量 PartiQL 查询的场景。
```
table_name = "doc-example-table-movies-partiql-#{rand(10**4)}"
scaffold = Scaffold.new(table_name)
sdk = DynamoDBPartiQLBatch.new(table_name)
new_step(1, 'Create a new DynamoDB table if none already exists.')
unless scaffold.exists?(table_name)
puts("\nNo such table: #{table_name}. Creating it...")
scaffold.create_table(table_name)
print "Done!\n".green
end
new_step(2, 'Populate DynamoDB table with movie data.')
download_file = 'moviedata.json'
puts("Downloading movie database to #{download_file}...")
movie_data = scaffold.fetch_movie_data(download_file)
puts("Writing movie data from #{download_file} into your table...")
scaffold.write_batch(movie_data)
puts("Records added: #{movie_data.length}.")
print "Done!\n".green
new_step(3, 'Select a batch of items from the movies table.')
puts "Let's select some popular movies for side-by-side comparison."
response = sdk.batch_execute_select([['Mean Girls', 2004], ['Goodfellas', 1977], ['The Prancing of the Lambs', 2005]])
puts("Items selected: #{response['responses'].length}\n")
print "\nDone!\n".green
new_step(4, 'Delete a batch of items from the movies table.')
sdk.batch_execute_write([['Mean Girls', 2004], ['Goodfellas', 1977], ['The Prancing of the Lambs', 2005]])
print "\nDone!\n".green
new_step(5, 'Delete the table.')
return unless scaffold.exists?(table_name)
scaffold.delete_table
end
```
+ 有关 API 的详细信息，请参阅 *适用于 Ruby 的 AWS SDK API 参考[BatchExecuteStatement](https://docs.aws.amazon.com/goto/SdkForRubyV3/dynamodb-2012-08-10/BatchExecuteStatement)*中的。
### 使用 PartiQL 来查询表
以下代码示例展示了如何：
+ 通过运行 SELECT 语句来获取项目。
+ 通过运行 INSERT 语句来添加项目。
+ 通过运行 UPDATE 语句来更新项目。
+ 通过运行 DELETE 语句来删除项目。
**适用于 Ruby 的 SDK**
还有更多相关信息 GitHub。在 [AWS 代码示例存储库](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/ruby/example_code/dynamodb#code-examples)中查找完整示例，了解如何进行设置和运行。
运行创建表并运行 PartiQL 查询的场景。
```
table_name = "doc-example-table-movies-partiql-#{rand(10**8)}"
scaffold = Scaffold.new(table_name)
sdk = DynamoDBPartiQLSingle.new(table_name)
new_step(1, 'Create a new DynamoDB table if none already exists.')
unless scaffold.exists?(table_name)
puts("\nNo such table: #{table_name}. Creating it...")
scaffold.create_table(table_name)
print "Done!\n".green
end
new_step(2, 'Populate DynamoDB table with movie data.')
download_file = 'moviedata.json'
puts("Downloading movie database to #{download_file}...")
movie_data = scaffold.fetch_movie_data(download_file)
puts("Writing movie data from #{download_file} into your table...")
scaffold.write_batch(movie_data)
puts("Records added: #{movie_data.length}.")
print "Done!\n".green
new_step(3, 'Select a single item from the movies table.')
response = sdk.select_item_by_title('Star Wars')
puts("Items selected for title 'Star Wars': #{response.items.length}\n")
print response.items.first.to_s.yellow
print "\n\nDone!\n".green
new_step(4, 'Update a single item from the movies table.')
puts "Let's correct the rating on The Big Lebowski to 10.0."
sdk.update_rating_by_title('The Big Lebowski', 1998, 10.0)
print "\nDone!\n".green
new_step(5, 'Delete a single item from the movies table.')
puts "Let's delete The Silence of the Lambs because it's just too scary."
sdk.delete_item_by_title('The Silence of the Lambs', 1991)
print "\nDone!\n".green
new_step(6, 'Insert a new item into the movies table.')
puts "Let's create a less-scary movie called The Prancing of the Lambs."
sdk.insert_item('The Prancing of the Lambs', 2005, 'A movie about happy livestock.', 5.0)
print "\nDone!\n".green
new_step(7, 'Delete the table.')
return unless scaffold.exists?(table_name)
scaffold.delete_table
end
```
+ 有关 API 的详细信息，请参阅 *适用于 Ruby 的 AWS SDK API 参考[ExecuteStatement](https://docs.aws.amazon.com/goto/SdkForRubyV3/dynamodb-2012-08-10/ExecuteStatement)*中的。
## 无服务器示例
### 通过 DynamoDB 触发器调用 Lambda 函数
以下代码示例演示如何实现一个 Lambda 函数，该函数接收通过接收来自 DynamoDB 流的记录而触发的事件。该函数检索 DynamoDB 有效负载，并记录下记录内容。
**适用于 Ruby 的 SDK**
还有更多相关信息 GitHub。在[无服务器示例](https://github.com/aws-samples/serverless-snippets/tree/main/integration-ddb-to-lambda)存储库中查找完整示例，并了解如何进行设置和运行。
通过 Ruby 将 DynamoDB 事件与 Lambda 结合使用。
```
def lambda_handler(event:, context:)
return 'received empty event' if event['Records'].empty?
event['Records'].each do |record|
log_dynamodb_record(record)
end
"Records processed: #{event['Records'].length}"
end
def log_dynamodb_record(record)
puts record['eventID']
puts record['eventName']
puts "DynamoDB Record: #{JSON.generate(record['dynamodb'])}"
end
```
### 通过 DynamoDB 触发器报告 Lambda 函数批处理项目失败
以下代码示例演示如何为接收来自 DynamoDB 流的事件的 Lambda 函数实现部分批处理响应。该函数在响应中报告批处理项目失败，并指示 Lambda 稍后重试这些消息。
**适用于 Ruby 的 SDK**
还有更多相关信息 GitHub。在[无服务器示例](https://github.com/aws-samples/serverless-snippets/tree/main/integration-ddb-to-lambda-with-batch-item-handling)存储库中查找完整示例，并了解如何进行设置和运行。
报告使用 Ruby 通过 Lambda 进行 DynamoDB 批处理项目失败。
```
def lambda_handler(event:, context:)
records = event["Records"]
cur_record_sequence_number = ""
records.each do |record|
begin
# Process your record
cur_record_sequence_number = record["dynamodb"]["SequenceNumber"]
rescue StandardError => e
# Return failed record's sequence number
return {"batchItemFailures" => [{"itemIdentifier" => cur_record_sequence_number}]}
end
end
{"batchItemFailures" => []}
end
```