Class: ActiveItem::Transaction

Inherits:
Object
  • Object
show all
Defined in:
lib/active_item/transaction.rb

Overview

Wraps DynamoDB TransactWriteItems, allowing multiple put, update, and delete operations to be committed atomically (up to 100 items).

Supports two usage patterns:

  1. Explicit API (original):

    Model.transaction do |txn|
txn.put(record1)
txn.update(record2)
end

  2. Implicit API (transactional saves):

    Model.transaction do
record1.save!
record2.save!
record3.destroy!
end

In the implicit API, save/destroy calls inside the block are automatically enrolled in the transaction and committed atomically at block end.

Constant Summary collapse

MAX_ITEMS = 
100

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Transaction

Returns a new instance of Transaction.



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# File 'lib/active_item/transaction.rb', line 40

def initialize
  @operations = []
end

Instance Attribute Details

#operations ⇒ Object (readonly)

Returns the value of attribute operations.



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# File 'lib/active_item/transaction.rb', line 27

def operations
  @operations
end

Class Method Details

.active? ⇒ Boolean

Check if we're inside a transaction block

Returns:

  • (Boolean) 


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# File 'lib/active_item/transaction.rb', line 45

def self.active?
  !current.nil?
end

.current ⇒ Object

Thread-local storage for the current transaction context



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# File 'lib/active_item/transaction.rb', line 31

def current
  Thread.current[:activeitem_current_transaction]
end

.current=(txn) ⇒ Object 



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# File 'lib/active_item/transaction.rb', line 35

def current=(txn)
  Thread.current[:activeitem_current_transaction] = txn
end

Instance Method Details

#delete(record) ⇒ Object 



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# File 'lib/active_item/transaction.rb', line 69

def delete(record)
  @operations << {
    op: { delete: { table_name: record.class.table_name, key: { record.class.primary_key.to_s => record.id } } },
    record: record, type: :delete
  }
end

#execute! ⇒ Object 



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# File 'lib/active_item/transaction.rb', line 117

def execute!
  return if @operations.empty?
  raise TransactionError, "DynamoDB transactions are limited to #{MAX_ITEMS} items (got #{@operations.length})" if @operations.length > MAX_ITEMS

  transact_items = @operations.map { |o| o[:op] }
  client = @operations.first[:record].class.dynamodb
  client.transact_write_items(transact_items: transact_items)

  @operations.each do |o|
    o[:record].instance_variable_set(:@new_record, false) if o[:type] == :put
  end
rescue Aws::DynamoDB::Errors::TransactionCanceledException => e
  raise TransactionError, "Transaction cancelled: #{e.message}"
rescue Aws::DynamoDB::Errors::ValidationException => e
  raise TransactionError, "Transaction validation failed: #{e.message}"
end

#put(record, condition: nil) ⇒ Object 



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# File 'lib/active_item/transaction.rb', line 49

def put(record, condition: nil)
  record.instance_variable_set(:@id, SecureRandom.uuid) unless record.id
  pk = record.class.primary_key
  record.instance_variable_set(:"@#{pk}", record.id) if pk != 'id'
  now = Time.now.utc.iso8601
  record.instance_variable_set(:@created_at, now) unless record.created_at
  record.instance_variable_set(:@updated_at, now)

  item = record.send(:build_dynamodb_item).merge(
    'createdAt' => record.created_at,
    'updatedAt' => record.updated_at,
    '_recent_pk' => 'ALL'
  )

  op = { put: { table_name: record.class.table_name, item: item } }
  op[:put][:condition_expression] = condition if condition

  @operations << { op: op, record: record, type: :put }
end

#update(record) ⇒ Object 



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# File 'lib/active_item/transaction.rb', line 76

def update(record)
  changes = record.changes
  return if changes.empty?

  set_parts = []
  remove_parts = []
  attr_values = {}
  attr_names = {}

  changes.each_with_index do |(field, (_old_val, new_val)), idx|
    dynamo_key = record.class.to_dynamo_key(field)
    if new_val.nil?
      remove_parts << "#f#{idx}"
      attr_names["#f#{idx}"] = dynamo_key
    else
      set_parts << "#f#{idx} = :v#{idx}"
      attr_names["#f#{idx}"] = dynamo_key
      attr_values[":v#{idx}"] = new_val
    end
  end

  set_parts << 'updatedAt = :ts'
  attr_values[':ts'] = Time.now.utc.iso8601

  update_expression = "SET #{set_parts.join(', ')}"
  update_expression += " REMOVE #{remove_parts.join(', ')}" if remove_parts.any?

  @operations << {
    op: {
      update: {
        table_name: record.class.table_name,
        key: { record.class.primary_key.to_s => record.id },
        update_expression: update_expression,
        expression_attribute_names: attr_names.any? ? attr_names : nil,
        expression_attribute_values: attr_values
      }.compact
    },
    record: record, type: :update
  }
end