How to add support for pre updateItem hook for keystone.List.

keystone_hacks.js

// Naturally this has to be done before creating List instances!!

// monkey patching List constructor to add hooks support
(function () {
  var grappling = require('grappling-hook');
  var List = keystone.List;

  keystone.List = function (name, options) {
    List.apply(this, arguments);

    grappling.mixin(this).allowHooks('pre:updateItem');

    if (options && options.pre && options.pre.updateItem) {
      this.pre('updateItem', options.pre.updateItem);
    }
  }
  keystone.List.prototype = List.prototype;
})();

// monkey patching List#updateItem to call hook
(function () {
  var updateItem = keystone.List.prototype.updateItem;

  keystone.List.prototype.updateItem = function (item, data, options, callback) {
    var self = this;

    /* Process arguments and options */
    if (typeof options === 'function') {
      callback = options;
      options = {};
    }
    if (!options) {
      options = {};
    }

    this.callHook('pre:updateItem', item, data, options, function (err) {
      if (err) {
        return callback(err);
      }
      updateItem.call(self, item, data, options, callback);
    })
  }
})();


/// Now we can do this..
var MyModel = new Keystone.List('MyModel');
MyModel.pre('updateItem', function (item, data, options, next) {
  // do something and then
  next()
})