getAllCategories() {
    let categories = []
    try {
      this.localDataService.categories.allDocs({
        include_docs: true,
        attachments: true
      }).then((result) => {
        for (let i = 0; i < result.rows.length; i++) {
          categories.push(result.rows[i].doc);
        }
      });
    } catch (err) {
      console.log(err);
      return null;
    }
    return categories;
  }