loopback-datasource-juggler/lib/hooks.js

/**
 * Module exports
 */
module.exports = Hookable;

/**
 * Hooks mixins
 */

function Hookable() {
}

/**
 * List of hooks available
 */
Hookable.afterInitialize = null;
Hookable.beforeValidate = null;
Hookable.afterValidate = null;
Hookable.beforeSave = null;
Hookable.afterSave = null;
Hookable.beforeCreate = null;
Hookable.afterCreate = null;
Hookable.beforeUpdate = null;
Hookable.afterUpdate = null;
Hookable.beforeDestroy = null;
Hookable.afterDestroy = null;

// TODO: Evaluate https://github.com/bnoguchi/hooks-js/
Hookable.prototype.trigger = function trigger(actionName, work, data) {
  var capitalizedName = capitalize(actionName);
  var beforeHook = this.constructor["before" + capitalizedName]
    || this.constructor["pre" + capitalizedName];
  var afterHook = this.constructor["after" + capitalizedName]
    || this.constructor["post" + capitalizedName];
  if (actionName === 'validate') {
    beforeHook = beforeHook || this.constructor.beforeValidation;
    afterHook = afterHook || this.constructor.afterValidation;
  }
  var inst = this;

  // we only call "before" hook when we have actual action (work) to perform
  if (work) {
    if (beforeHook) {
      // before hook should be called on instance with one param: callback
      beforeHook.call(inst, function () {
        // actual action also have one param: callback
        work.call(inst, next);
      }, data);
    } else {
      work.call(inst, next);
    }
  } else {
    next();
  }

  function next(done) {
    if (afterHook) {
      afterHook.call(inst, done);
    } else if (done) {
      done.call(this);
    }
  }
};

function capitalize(string) {
  return string.charAt(0).toUpperCase() + string.slice(1);
}