Module: IronTrail::Reifier

Defined in:
lib/iron_trail/reifier.rb

Class Method Summary collapse

Class Method Details

.model_from_table_name(table_name, sti_type = nil) ⇒ Object 



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# File 'lib/iron_trail/reifier.rb', line 28

def self.model_from_table_name(table_name, sti_type = nil)
  candidates = ActiveRecord::Base.descendants
    .reject(&:abstract_class)
    .select { |klass| klass.table_name == table_name }

  raise "Cannot infer model from table named '#{table_name}'" if candidates.empty?
  return candidates.first if candidates.one?

  if sti_type.present?
    klass = candidates.find { |c| c.name == sti_type }
    return klass if klass

    raise "Cannot infer STI model for table #{table_name} and type '#{sti_type}'"
  end

  # When sti_type is nil and multiple classes share the table,
  # filter out STI subclasses to find the base class.
  bases = candidates.reject { |c| candidates.any? { |other| other != c && c < other } }
  return bases.first if bases.one?

  # If multiple base classes remain, prefer the one that is an STI base
  # (i.e., has subclasses among the original candidates).
  sti_bases = bases.select { |c| candidates.any? { |other| other != c && other < c } }
  return sti_bases.first if sti_bases.one?

  raise "Cannot infer model from table named '#{table_name}'"
end

.reify(trail) ⇒ Object 



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# File 'lib/iron_trail/reifier.rb', line 5

def self.reify(trail)
  source_attributes = (trail.delete_operation? ? trail.rec_old : trail.rec_new)
  klass = model_from_table_name(trail.rec_table, source_attributes['type'])

  record = klass.where(id: trail.rec_id).first || klass.new

  source_attributes.each do |name, value|
    if record.has_attribute?(name)
      attr_type = record.type_for_attribute(name)
      record[name] = attr_type.deserialize(value)
    else
      ghost = record.instance_variable_get(:@irontrail_reified_ghost_attributes)
      unless ghost
        ghost = HashWithIndifferentAccess.new
        record.instance_variable_set(:@irontrail_reified_ghost_attributes, ghost)
      end
      ghost[name] = value
    end
  end

  record
end