Module: Provenance::Trackable

Extended by:
ActiveSupport::Concern
Defined in:
lib/provenance/trackers/trackable.rb

Overview

Model-side concern. Captures create/update/destroy through ActiveRecord callbacks, groups changes by transaction key, discards them on rollback and flushes the audit log once every transaction has committed. Also tracks ‘has_and_belongs_to_many` join-table changes, which bypass model callbacks, via SQL notifications.

Constant Summary collapse

INSERT_DELETE_REGEX = 
/\b(INSERT|DELETE)\s+(INTO|FROM)\b/i
INSERT_INTO_REGEX = 
/\bINSERT\s+INTO\b/i
TABLE_NAME_REGEX = 
/(?:INSERT\s+INTO|DELETE\s+FROM)\s+["`]?(\w+)["`]?/i
INSERT_COLUMNS_REGEX = 
/INSERT\s+INTO\s+["`]?\w+["`]?\s*\(([^)]+)\)/i
WHERE_REGEX = 
/WHERE\s+(.+?)(?:\s+RETURNING|\s*$)/i

Class Method Summary collapse

Class Method Details

.extract_delete_values(sql, binds, foreign_key, association_foreign_key) ⇒ Object 



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# File 'lib/provenance/trackers/trackable.rb', line 146

def self.extract_delete_values(sql, binds, foreign_key, association_foreign_key)
  conditions = sql.match(WHERE_REGEX)&.[](1)
  return nil unless conditions

  fk_pattern = /(?:["`]\w+["`]\.)?["`]?#{Regexp.escape(foreign_key)}["`]?\s*[=<>]\s*\$(\d+)/i
  fk_match = conditions.match(fk_pattern)
  return nil unless fk_match

  fk_idx = fk_match[1].to_i - 1
  return nil unless binds[fk_idx]

  afk_pattern = /(?:["`]\w+["`]\.)?["`]?#{Regexp.escape(association_foreign_key)}["`]?\s*[=<>]\s*\$(\d+)/i
  afk_match = conditions.match(afk_pattern)

  if afk_match
    afk_idx = afk_match[1].to_i - 1
    return nil unless binds[afk_idx]

    [extract_value(binds[fk_idx]), extract_value(binds[afk_idx])]
  else
    in_params = conditions.match(/#{Regexp.escape(association_foreign_key)}["`]?\s+IN\s*\(([^)]+)\)/i)&.[](1)
    return nil unless in_params

    param_indices = in_params.scan(/\$(\d+)/).flatten.map(&:to_i).map { |i| i - 1 }
    associated_ids = param_indices.filter_map { |idx| extract_value(binds[idx]) if binds[idx] }
    return nil if associated_ids.empty?

    [extract_value(binds[fk_idx]), associated_ids]
  end
end

.extract_habtm_values(sql, binds, action, foreign_key, association_foreign_key) ⇒ Object 



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# File 'lib/provenance/trackers/trackable.rb', line 124

def self.extract_habtm_values(sql, binds, action, foreign_key, association_foreign_key)
  return nil unless binds

  if action == :add
    extract_insert_values(sql, binds, foreign_key, association_foreign_key)
  else
    extract_delete_values(sql, binds, foreign_key, association_foreign_key)
  end
end

.extract_insert_values(sql, binds, foreign_key, association_foreign_key) ⇒ Object 



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# File 'lib/provenance/trackers/trackable.rb', line 134

def self.extract_insert_values(sql, binds, foreign_key, association_foreign_key)
  columns = sql.match(INSERT_COLUMNS_REGEX)&.[](1)
  return nil unless columns

  columns = columns.split(",").map { |c| c.strip.delete('"`') }
  fk_idx = columns.index(foreign_key)
  afk_idx = columns.index(association_foreign_key)
  return nil unless fk_idx && afk_idx && binds[fk_idx] && binds[afk_idx]

  [extract_value(binds[fk_idx]), extract_value(binds[afk_idx])]
end

.extract_value(bind) ⇒ Object 



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# File 'lib/provenance/trackers/trackable.rb', line 177

def self.extract_value(bind)
  return bind.value if bind.respond_to?(:value)
  return bind.value_for_database if bind.respond_to?(:value_for_database)

  bind
end

.habtm_join_tables ⇒ Object 



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# File 'lib/provenance/trackers/trackable.rb', line 94

def self.habtm_join_tables
  @habtm_join_tables ||= {}
end

.included(base) ⇒ Object 



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# File 'lib/provenance/trackers/trackable.rb', line 21

def self.included(base)
  super

  base.class_eval do
    before_create :capture_transaction_id
    before_update :capture_transaction_id
    before_destroy :capture_transaction_id

    after_update :capture_update
    after_create :capture_create
    after_destroy :capture_destroy

    after_commit :try_send_audit_after_commit
    after_rollback :clear_tracked_changes

    class << self
      alias_method :original_has_and_belongs_to_many, :has_and_belongs_to_many

      def has_and_belongs_to_many(name, scope = nil, **options, &extension)
        original_has_and_belongs_to_many(name, scope, **options, &extension).tap do
          association = reflect_on_association(name)
          next unless association

          Provenance::Trackable.register_habtm_join_table_from_association(association, self.name, name)
        end
      end
    end

    base.setup_habtm_tracking
  end

  # has_and_belongs_to_many join-table writes bypass model callbacks, so we
  # observe them through SQL notifications and fold them into the journal.
  # The change is recorded synchronously on the request thread; delivery is
  # handled by Auditable once every transaction has committed, so no extra
  # post-commit scheduling is required here.
  return if @habtm_sql_subscribed

  ActiveSupport::Notifications.subscribe("sql.active_record") do |_name, _start, _finish, _id, payload|
    Provenance::Trackable.track_habtm_sql_changes(payload)
  end
  @habtm_sql_subscribed = true
end

.register_habtm_join_table_from_association(association, model_class_name, association_name) ⇒ Object

Registry of join tables we watch, keyed by table name. Populated when a model that includes Trackable declares a has_and_belongs_to_many.



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# File 'lib/provenance/trackers/trackable.rb', line 83

def self.register_habtm_join_table_from_association(association, model_class_name, association_name)
  join_table = association.join_table
  (@habtm_join_tables ||= {})[join_table] ||= []
  @habtm_join_tables[join_table] << {
    model_class_name: model_class_name,
    association_name: association_name,
    foreign_key: association.foreign_key,
    association_foreign_key: association.association_foreign_key
  }
end

.track_habtm_sql_changes(payload) ⇒ Object

Inspects a SQL statement; if it touches a watched join table, reconstructs the affected ids and folds the change into the journal as an update.



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# File 'lib/provenance/trackers/trackable.rb', line 100

def self.track_habtm_sql_changes(payload)
  journal = Provenance::Context.journal
  return unless journal

  sql = payload[:sql].to_s
  return unless sql.match?(INSERT_DELETE_REGEX)

  table_name = sql.match(TABLE_NAME_REGEX)&.[](1)
  return unless table_name && (info_list = habtm_join_tables[table_name])

  action = sql.match?(INSERT_INTO_REGEX) ? :add : :remove

  info_list.each do |info|
    values_list = extract_habtm_values(sql, payload[:binds], action, info[:foreign_key], info[:association_foreign_key])
    next unless values_list

    model = info[:model_class_name].constantize.find_by(id: values_list[0])
    next unless model&.persisted?

    associated_ids = Array(values_list[1])
    model.send(:track_habtm_changes, info[:association_name], action, associated_ids)
  end
end