Question: How to update state in selector get?

[StringKe]

const rawPageId = atom<number | undefined>({
  key: 'raw-page-id',
  default: undefined,
});
const rawTemplateData = atom<DesignPage<PageElementsProps>[]>({
  key: 'raw-template-data',
  default: [],
});

const usePageId = selector({
  key: 'get-page-id',
  get({ get }) {
    const id = get(rawPageId);
    if (id) {
      return id;
    }
    const template = get(rawTemplateData);
    // set first page id;
    if (template.length) {
      const firstId = template[0].id;
      // hope update rawPageId
    }
    // create empty page;
    // do create empty page, hope add new data in rawTemplateData
  },
});

I want to get the correct data when using usePageId. What do I need to do?