amee-data-persistence¶ ↑
The amee-data-persistence gem provides database support for use in conjunction with the amee-data-abstraction gem.
Licensed under the BSD 3-Clause license (See LICENSE.txt for details)
Authors: James Hetherington, James Smith, Andrew Berkeley, George Palmer
Copyright: Copyright © 2011 AMEE
UK Ltd
Homepage: github.com/AMEE/amee-data-persistence
Documentation: rubydoc.info/gems/amee-data-persistence
INSTALLATION¶ ↑
gem install amee-data-persistence
REQUIREMENTS¶ ↑
* ruby 1.8.7 * rubygems >= 1.5 All gem requirements should be installed as part of the rubygems installation process above, but are listed here for completeness. * amee-data-abstraction ~> 1.0.0
USAGE¶ ↑
The library repesents calculations as database records using two classes (AMEE::Db::Calculation and AMEE::Db::Term) both of which inherit ActiveRecord::Base.
The library also defines the AMEE::DataAbstraction::PersistenceSupport module which is mixed into the AMEE::DataAbstraction::OngoingCalculation class by default when the library is required. The module provides a number of class and instance methods which provide an interface between the AMEE::DataAbstraction::OngoingCalculation class (and its instances) and the database. It is via these methods that the persistence functionality provided by the AMEE::Db classes is principally used.
The level of data storage can be configured to three distinct levels, representing the range of calculation terms which are persisted: all; outputs and metadata only; and metadata only.
The global persistence storage level and migrations for the database tables (under /db/migrate) can be generated using the command line generator command:
$ rails generate persistence <storage_level>
where <storage_level> can be either ‘everything’, ‘outputs’ or ‘metadata’, e.g.,
$ rails generate persistence everything
Example usage¶ ↑
my_calculation = OngoingCalculation.find(:first) #=> <AMEE::DataAbstraction::OngoingCalculation ... > my_calculation = OngoingCalculation.find(28) #=> <AMEE::DataAbstraction::OngoingCalculation ... > my_calculation = OngoingCalculation.find(:all) #=> <AMEE::DataAbstraction::CalculationCollection ... > my_calculation = OngoingCalculation.find_by_type(:all, :electricity) #=> <AMEE::DataAbstraction::CalculationCollection ... > my_calculation.id #= 28 my_calculation.db_calculation #=> <AMEE::Db::Calculation ... > my_calculation.to_hash #=> { :profile_uid => "EYR758EY36WY", :profile_item_uid => "W83URT48DY3W", :type => { :value => 'car' }, :distance => { :value => 1600, :unit => <Quantify::Unit::SI> }, :co2 => { :value => 234.1, :unit => <Quantify::Unit::NonSI> }} my_calculation.save #=> true my_calculation.delete #=> nil
n order to use the persistence library, prototype calculations must be held within instances of the AMEE::DataAbstraction::CalculationSet class