115 lines
3.9 KiB
Ruby
115 lines
3.9 KiB
Ruby
class Version < ActiveRecord::Base
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belongs_to :item, :polymorphic => true
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validates_presence_of :event
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# Restore the item from this version.
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#
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# This will automatically restore all :has_one associations as they were "at the time",
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# if they are also being versioned by PaperTrail. NOTE: this isn't always guaranteed
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# to work so you can either change the lookback period (from the default 3 seconds) or
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# opt out.
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#
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# Options:
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# +:has_one+ set to `false` to opt out of has_one reification.
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# set to a float to change the lookback time (check whether your db supports
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# sub-second datetimes if you want them).
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def reify(options = {})
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options.reverse_merge! :has_one => 3
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unless object.nil?
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attrs = YAML::load object
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# Normally a polymorphic belongs_to relationship allows us
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# to get the object we belong to by calling, in this case,
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# +item+. However this returns nil if +item+ has been
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# destroyed, and we need to be able to retrieve destroyed
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# objects.
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#
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# In this situation we constantize the +item_type+ to get hold of
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# the class...except when the stored object's attributes
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# include a +type+ key. If this is the case, the object
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# we belong to is using single table inheritance and the
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# +item_type+ will be the base class, not the actual subclass.
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# If +type+ is present but empty, the class is the base class.
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if item
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model = item
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else
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class_name = attrs['type'].blank? ? item_type : attrs['type']
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klass = class_name.constantize
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model = klass.new
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end
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attrs.each do |k, v|
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begin
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model.send :write_attribute, k.to_sym , v
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rescue NoMethodError
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logger.warn "Attribute #{k} does not exist on #{item_type} (Version id: #{id})."
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end
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end
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model.version = self
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unless options[:has_one] == false
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reify_has_ones model, options[:has_one]
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end
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model
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end
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end
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# Returns who put the item into the state stored in this version.
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def originator
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previous.try :whodunnit
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end
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# Returns who changed the item from the state it had in this version.
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# This is an alias for `whodunnit`.
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def terminator
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whodunnit
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end
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def next
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Version.first :conditions => ["id > ? AND item_type = ? AND item_id = ?", id, item_type, item_id],
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:order => 'id ASC'
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end
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def previous
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Version.first :conditions => ["id < ? AND item_type = ? AND item_id = ?", id, item_type, item_id],
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:order => 'id DESC'
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end
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def index
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Version.all(:conditions => ["item_type = ? AND item_id = ?", item_type, item_id],
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:order => 'id ASC').index(self)
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end
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private
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# Restore the `model`'s has_one associations as they were when this version was
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# superseded by the next (because that's what the user was looking at when they
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# made the change).
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#
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# The `lookback` sets how many seconds before the model's change we go.
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def reify_has_ones(model, lookback)
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model.class.reflect_on_all_associations(:has_one).each do |assoc|
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child = model.send assoc.name
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if child.respond_to? :version_at
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# N.B. we use version of the child as it was `lookback` seconds before the parent was updated.
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# Ideally we want the version of the child as it was just before the parent was updated...
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# but until PaperTrail knows which updates are "together" (e.g. parent and child being
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# updated on the same form), it's impossible to tell when the overall update started;
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# and therefore impossible to know when "just before" was.
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if (child_as_it_was = child.version_at(created_at - lookback.seconds))
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child_as_it_was.attributes.each do |k,v|
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model.send(assoc.name).send :write_attribute, k.to_sym, v rescue nil
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end
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else
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model.send "#{assoc.name}=", nil
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end
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end
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end
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end
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end
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