TypeError:无法将Nokogiri::XML::Attr转换为string

Question

我试图抓取一些数据并找到或创建一个Rails对象，代码如下：

@books = @page.xpath(BOOKS_SELECTOR).map { |book| Book.find_or_create_by(name: book.attribute('title'))}

但是，当这段代码运行时，我会得到以下错误：

  1) Error:
ScrapeHelperTest#test_scrape_page_test:
TypeError: can't cast Nokogiri::XML::Attr to string
    app/helpers/scrape_helper.rb:25:in `block in scrape'
    app/helpers/scrape_helper.rb:25:in `map'
    app/helpers/scrape_helper.rb:25:in `scrape'
    test/helpers/scrape_helper_test.rb:11:in `block in <class:ScrapeHelperTest>'

Answer 1

@books = @page.xpath(BOOKS_SELECTOR).map do |book| 
  Book.find_or_create_by(name: book['title'])
end

使用散列访问器，节点上的[]返回属性值，而不是#attribute返回的Nokogiri::XML::Attr节点。