backend: [
    {
      category: 'backend',
      slug: 'spring-action',
      store: 'http://www.amazon.cn/Spring%E5%AE%9E%E6%88%98-%E6%B2%83%E5%B0%94%E6%96%AF/dp/B00CY6UD2I/ref=sr_1_1?s=books&ie=UTF8&qid=1453001646&sr=1-1&keywords=Spring%E5%AE%9E%E6%88%98',