Class: StandardLedger::Modes::Trigger

Inherits:
Object
  • Object
show all
Defined in:
lib/standard_ledger/modes/trigger.rb

Overview

‘:trigger` mode: the host owns a database trigger (created in a Rails migration) that updates the projection target’s columns on every entry INSERT. The gem records the trigger’s name and the equivalent rebuild SQL, but does not create or manage the trigger itself —giving a Ruby DSL the power to install/replace triggers is a deploy footgun (silent re-creation on ‘db:schema:load` against a non-empty DB), and triggers are versioned by `db/schema.rb` like any other DDL.

Two consumers read the recorded metadata:

  • ‘StandardLedger.rebuild!` runs the rebuild SQL when invoked, binding `:target_id` to each target the log references. The same recompute path as `:sql` mode — the only difference is that the after-create application is performed by the database trigger rather than a Ruby callback.

  • The ‘standard_ledger:doctor` rake task verifies that the named trigger exists in the connected schema. Migration drift (a missing or renamed trigger) is caught at deploy time, not at runtime.

Unlike ‘:inline` and `:sql`, this strategy does NOT install an `after_create` callback — the trigger fires from the database. The `install!` no-op only marks the entry class as having at least one `:trigger` projection registered (mirrors the `Modes::Matview` shape).

See ‘standard_ledger-design.md` §5.3.4 for the full contract.

Class Method Summary collapse

Class Method Details

.install!(_entry_class) ⇒ void

This method returns an undefined value.

Mark the entry class as having at least one ‘:trigger` projection registered. The actual trigger metadata lives on the entry class’s ‘standard_ledger_projections` array; this method exists only to mirror the `Modes::*.install!` shape so `Projector#install_mode_callbacks_for` can dispatch uniformly across modes.

No ‘after_create` callback is installed — the trigger runs in the database, not Ruby. Idempotent across multiple `:trigger` projections on the same entry class.

Parameters:

  • entry_class (Class) —

    the host entry class (unused — kept for parity with the other strategy classes).



42
43
44
45
46
47
 
# File 'lib/standard_ledger/modes/trigger.rb', line 42

def self.install!(_entry_class)
  # Intentionally empty: trigger projections fire from the DB, so
  # there's no Ruby-side callback to wire. The DSL has already
  # captured `trigger_name` and `recompute_sql` on the Definition;
  # `rebuild!` and the `doctor` rake task consume those directly.
end