使用Ruby了解AWS DynamoDB中的属性

下面是我的示例代码,希望能帮助其他人,我在这里有一个完整的例子：https://gist.github.com/Integralist/9f9f2215e001b15ac492#file-3-dynamodb-irb-session-rb

# https://github.com/BBC-News/alephant-harness can automate the below set-up when using Spurious
# API Documentation http://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_Operations.html
# Ruby SDK API Documentation http://docs.aws.amazon.com/AWSRubySDK/latest/frames.html#!AWS/DynamoDB/Client/V20120810.html

require "aws-sdk"
require "dotenv"
require "spurious/ruby/awssdk/helper"

Spurious::Ruby::Awssdk::Helper.configure
# => <AWS::Core::Configuration>

Dotenv.load(
  File.join(
    File.dirname(__FILE__),"config","development","env.yaml"
  )
)
# => {"AWS_REGION"=>"eu-west-1","AWS_ACCESS_KEY_ID"=>"development_access","AWS_SECRET_ACCESS_KEY"=>"development_secret","DYNAMO_LU"=>"development_lookup","DYNAMO_SQ"=>"development_sequence","SQS_QUEUE"=>"development_queue","S3_BUCKET"=>"development_bucket"}

dyn = AWS::DynamoDB::Client.new :api_version => "2012-08-10"
dyn = AWS::DynamoDB::Client::V20120810.new
# => #<AWS::DynamoDB::Client::V20120810>

dyn.create_table({
  # This section requires us to define our primary key 
  # Which will be called "item_id" and it must be a numerical value
  :attribute_definitions => [
    { :attribute_name => "item_id",# The primary key will be a simple Hash key (not a Hash/Range which requires both key types to be provided)
  # The attributes defined above must be included in the :key_schema Array
  :key_schema => [
    { :attribute_name => "item_id",:key_type => "HASH" }
  ],:scanned_count=>0}

dyn.put_item(
  :table_name => "my_books",:item => {
    "item_id" => { "N" => "1" },# oddly this needs to be a String and not a strict Integer?
    "item_title" => { "S" => "My Book Title"},"item_released" => { "B" => "false" }
  }
)
# Note: if you use an "item_id" that already exists,then the item will be updated.
#       Unless you use the "expected" conditional feature

dyn.put_item(
  :table_name => "my_books","item_released" => { "B" => "false" }
  },# The :expected key specifies the conditions of our "put" operation.
  # If "item_id" isn't NULL (i.e. it exists) then our condition has failed.
  # This means we only write the value when the key "item_id" hasn't been set.
  :expected => {
    "item_id" => { :comparison_operator => "NULL" }
  }
)
# AWS::DynamoDB::Errors::ConditionalCheckFailedException: The conditional check failed

dyn.scan :table_name => "my_books"
# => {:member=>[{"item_id"=>{:n=>"1"},"item_title"=>{:s=>"My Book Title"},"item_released"=>{:b=>"false"}}],:count=>1,:scanned_count=>1}

dyn.query :table_name => "my_books",:consistent_read => true,:key_conditions => {
  "item_id" => {
    :comparison_operator => "EQ",:attribute_value_list => [{ "n" => "1" }]
  },"item_title" => {
    :comparison_operator => "EQ",:attribute_value_list => [{ "s" => "My Book Title" }]
  }
}
# => {:member=>[{"item_id"=>{:n=>"1"},:select => "SPECIFIC_ATTRIBUTES",:attributes_to_get => ["item_title"],:attribute_value_list => [{ "s" => "My Book Title" }]
  }
}
# => {:member=>[{"item_title"=>{:s=>"My Book Title"}}],:scanned_count=>1}

dyn.delete_item(
  :table_name => "my_books",:key => {
    "item_id" => { "n" => "1" }
  }
)
# => {:member=>[],:scanned_count=>0}