Class: ActiveRecord::StatementCache

Inherits:

Object

• Object
• ActiveRecord::StatementCache

Defined in:

activerecord/lib/active_record/statement_cache.rb

Overview

Statement cache is used to cache a single statement in order to avoid creating the AST again. Initializing the cache is done by passing the statement in the initialization block:

cache = ActiveRecord::StatementCache.new do
  Book.where(name: "my book").limit(100)
end

The cached statement is executed by using the execute method:

cache.execute

The relation returned by the block is cached, and for each execute call the cached relation gets duped. Database is queried when to_a is called on the relation.

Instance Method Summary

• #execute ⇒ Object
• #initialize ⇒ StatementCache constructor

  A new instance of StatementCache.

Constructor Details

#initialize ⇒ StatementCache

Returns a new instance of StatementCache.

Raises:

• (ArgumentError)

# File 'activerecord/lib/active_record/statement_cache.rb', line 17

def initialize
  @relation = yield
  raise ArgumentError.new("Statement cannot be nil") if @relation.nil?
end

Instance Method Details

#execute ⇒ Object

# File 'activerecord/lib/active_record/statement_cache.rb', line 22

def execute
  @relation.dup.to_a
end