Module: ActiveFacts::API::Entity

Includes:
Instance
Defined in:
lib/activefacts/api/entity.rb

Overview

An Entity type is any ObjectType that isn’t a value type. All Entity types must have an identifier made up of one or more roles.

Defined Under Namespace

Modules: ClassMethods

Instance Attribute Summary

Attributes included from Instance

#constellation

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Instance

#instance_index, #is_a?, #related_entities, #retract

Class Method Details

.included(other) ⇒ Object

:nodoc:



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# File 'lib/activefacts/api/entity.rb', line 463

def self.included other #:nodoc:
  other.send :extend, ClassMethods

  def other.new_instance constellation, *args
    instance = allocate
    instance.instance_variable_set(@@constellation_variable_name ||= "@constellation", constellation)
    instance.send(:initialize, *args)
    instance
  end

  # Register ourselves with the parent module, which has become a Vocabulary:
  vocabulary = other.modspace
  unless vocabulary.respond_to? :object_type  # Extend module with Vocabulary if necessary
    vocabulary.send :extend, Vocabulary
  end
  vocabulary.__add_object_type(other)
end

Instance Method Details

#analyse_impacts(role) ⇒ Object

This role is identifying, so if is changed, not only must the current object be re-indexed, but also entities identified by this entity. Save the current key and class for each such instance. This function is transitive!



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# File 'lib/activefacts/api/entity.rb', line 162

def analyse_impacts role
  impacts = []
  impacted_roles = []

  # Consider the object itself and all its supertypes
  ([self.class]+self.class.supertypes_transitive).map do |supertype|
    next unless supertype.identifying_roles.include?(role)

    old_key = identifying_role_values(supertype)
    # puts "Need to reindex #{self.class} as #{supertype} from #{old_key.inspect}"
    impacts << [constellation.instances[supertype], self, old_key]

    supertype.
    all_role.
    each do |role_name, propagation_role|
      next if role == propagation_role  # Propagation has already been taken care of
      next unless counterpart = propagation_role.counterpart  # And the role is not unary
      if counterpart.is_identifying                         # This object identifies another
        # puts "Changing #{propagation_role.inspect} affects #{counterpart.inspect}"
        impacted_roles << propagation_role
      else
        next if counterpart.unique                          # But a one-to-many
        next unless value = send(propagation_role.getter)   # A value is set
        role_values = value.send(counterpart.getter)        # This is the index we have to change
        # puts "Changing #{role.inspect} of a #{self.class} requires updating #{propagation_role.counterpart.inspect}"
        impacts << [role_values, self, old_key]
      end
    end
  end

  impacted_roles.each do |role|
    affected_instances = Array(send(role.getter))
    # puts "considering #{affected_instances.size} #{role.object_type.name} instances that include #{role.inspect}: #{affected_instances.map(&:identifying_role_values).inspect}"
    affected_instances.each do |counterpart|
      impacts.concat(counterpart.analyse_impacts(role.counterpart))
    end
  end
  impacts
end

#apply_impacts(impacts) ⇒ Object 



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# File 'lib/activefacts/api/entity.rb', line 202

def apply_impacts impacts
  impacts.each do |index, entity, old_key|
    new_key = entity.identifying_role_values(index.object_type)
    # puts "Reindexing #{klass} from #{old_key.inspect} to #{new_key.inspect}"

    if new_key != old_key
      index.delete_instance(entity, old_key)
      index.add_instance(entity, new_key)
    end
  end
end

#check_identification_change_legality(role, value) ⇒ Object

If this instance’s role is updated to the new value, does that cause a collision? We need to check each superclass that has a different identification pattern

Raises:



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# File 'lib/activefacts/api/entity.rb', line 216

def check_identification_change_legality(role, value)
  return unless @constellation && role.is_identifying

  klasses = [self.class] + self.class.supertypes_transitive
  last_identity = nil
  last_irns = nil
  counterpart_class = role.counterpart ? role.counterpart.object_type : value.class
  duplicate = klasses.detect do |klass|
    next false unless klass.identifying_roles.include?(role)
    irns = klass.identifying_role_names
    if last_irns != irns
      last_identity = identifying_role_values(klass)
      role_position = irns.index(role.name)
      last_identity[role_position] = value.identifying_role_values(counterpart_class)
    end
    @constellation.instances[klass][last_identity]
  end

  raise DuplicateIdentifyingValueException.new(self.class, role.name, value) if duplicate
end

#eql?(other) ⇒ Boolean

When used as a hash key, this entity instance is compared with another by comparing the values of its identifying roles

Returns:

  • (Boolean) 


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# File 'lib/activefacts/api/entity.rb', line 113

def eql?(other)
  if self.class == other.class
    identity_as_hash == other.identity_as_hash
  else
    false
  end
end

#hash ⇒ Object

When used as a hash key, the hash key of this entity instance is calculated by hashing the values of its identifying roles



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# File 'lib/activefacts/api/entity.rb', line 102

def hash
  self.class.identifying_roles.map{|role|
      instance_variable_get(role.variable)
    }.inject(0) { |h,v|
      h ^= v.hash
      h
    }
end

#identifying_role_values(klass = self.class) ⇒ Object

Return the array of the values of this instance’s identifying roles



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# File 'lib/activefacts/api/entity.rb', line 132

def identifying_role_values(klass = self.class)
  klass.identifying_roles.map do |role|
    value = send(role.name)
    counterpart_class = role.counterpart && role.counterpart.object_type
    value.identifying_role_values(counterpart_class)
  end
end

#identity_as_hash ⇒ Object

Identifying role values in a hash form.



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# File 'lib/activefacts/api/entity.rb', line 141

def identity_as_hash
  identity_by(self.class)
end

#identity_by(klass) ⇒ Object

Identifying role values in a hash form by class (entity).

Subtypes may have different identifying roles compared to their supertype, and therefore, a subtype entity may be identified differently if compared to one of its supertype.



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# File 'lib/activefacts/api/entity.rb', line 149

def identity_by(klass)
  roles_hash = {}
  klass.identifying_roles.each do |role|
    roles_hash[role.getter] = send(role.getter)
  end
  roles_hash
end

#inspect ⇒ Object

:nodoc:



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# File 'lib/activefacts/api/entity.rb', line 93

def inspect #:nodoc:
  irnv = self.class.identifying_role_names.map do |role_name|
    "#{role_name}: "+send(role_name).inspect
  end
  "<#{self.class.name} #{ irnv*', ' }>"
end

#verbalise(role_name = nil) ⇒ Object

Verbalise this entity instance



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# File 'lib/activefacts/api/entity.rb', line 122

def verbalise(role_name = nil)
  irnv = self.class.identifying_role_names.map do |role_sym|
      value = send(role_sym)
      identifying_role_name = self.class.all_role(role_sym).name.to_s.camelcase
      value ? value.verbalise(identifying_role_name) : "nil"
    end
  "#{role_name || self.class.basename}(#{ irnv*', ' })"
end