Module: ActiveEntity::Associations::ClassMethods

Defined in:
lib/active_entity/associations.rb

Overview

Associations are a set of macro-like class methods for tying objects together through foreign keys. They express relationships like “Project has one Project Manager” or “Project belongs to a Portfolio”. Each macro adds a number of methods to the class which are specialized according to the collection or association symbol and the options hash. It works much the same way as Ruby’s own attr* methods.

class Project < ActiveEntity::Base
  belongs_to              :portfolio
  has_one                 :project_manager
  has_many                :milestones
  has_and_belongs_to_many :categories
end

The project class now has the following methods (and more) to ease the traversal and manipulation of its relationships:

  • Project#portfolio, Project#portfolio=(portfolio), Project#reload_portfolio

  • Project#project_manager, Project#project_manager=(project_manager), Project#reload_project_manager

  • Project#milestones.empty?, Project#milestones.size, Project#milestones, Project#milestones<<(milestone), Project#milestones.delete(milestone), Project#milestones.destroy(milestone), Project#milestones.find(milestone_id), Project#milestones.build, Project#milestones.create

  • Project#categories.empty?, Project#categories.size, Project#categories, Project#categories<<(category1), Project#categories.delete(category1), Project#categories.destroy(category1)

A word of warning

Don’t create associations that have the same name as instance methods of ActiveEntity::Base. Since the association adds a method with that name to its model, using an association with the same name as one provided by ActiveEntity::Base will override the method inherited through ActiveEntity::Base and will break things. For instance, attributes and connection would be bad choices for association names, because those names already exist in the list of ActiveEntity::Base instance methods.

Instance Method Summary collapse

Instance Method Details

#association_names ⇒ Object 



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# File 'lib/active_entity/associations.rb', line 149

def association_names
  @association_names ||=
    if !abstract_class?
      reflections.keys.map(&:to_sym)
    else
      []
    end
end

#embedded_in(name, **options) ⇒ Object 



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# File 'lib/active_entity/associations.rb', line 134

def embedded_in(name, **options)
  reflection = Embeds::Builder::EmbeddedIn.build(self, name, options)
  Reflection.add_reflection self, name, reflection
end

#embeds_association_names ⇒ Object 



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# File 'lib/active_entity/associations.rb', line 158

def embeds_association_names
  @association_names ||=
    if !abstract_class?
      reflections.select { |_, r| r.embedded? }.keys.map(&:to_sym)
    else
      []
    end
end

#embeds_many(name, **options) ⇒ Object 



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# File 'lib/active_entity/associations.rb', line 144

def embeds_many(name, **options)
  reflection = Embeds::Builder::EmbedsMany.build(self, name, options)
  Reflection.add_reflection self, name, reflection
end

#embeds_one(name, **options) ⇒ Object 



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# File 'lib/active_entity/associations.rb', line 139

def embeds_one(name, **options)
  reflection = Embeds::Builder::EmbedsOne.build(self, name, options)
  Reflection.add_reflection self, name, reflection
end