我正在使用Mongoose、MongoDB和Nodejs，我想监听MongoDB集合的更改，并在更改前控制台记录文档和更新描述。
实际结果：我只能记录更新说明。

const didChangeStream = model.collection.watch({
  fullDocument: 'updateLookup',
  fullDocumentBeforeChange: 'whenAvailable'
});
didChangeStreamAlert.on('change', async (event) => {
  const {
    documentKey,
    fullDocument,
    fullDocumentBeforeChange,
    updateDescription
  } = event;
  console.log('fullDocumentBeforeChange', fullDocumentBeforeChange);
  console.log('updateDescription', updateDescription);
});