从 Rails 中的 HTML 个段落创建文本摘录

Question

我正在尝试提取一篇文章的摘录（markdown 解析为 HTML），其中仅包含段落中的纯文本。所有 HTML 都需要删除，换行符、制表符和顺序白色 space 需要替换为单个 space.

我的第一步是创建一个简单的测试：

describe "#from_html" do
  it "creates an excerpt from given HTML" do
    html = "<p>The spice extends <b>life</b>.<br>The spice    expands consciousness.</p>\n
           <ul><li>Skip me</li></ul>\n
           <p>The <i>spice</i> is vital to space travel.</p>"

    text = "The spice extends life. The spice expands consciousness. The spice is vital to space travel."

    expect(R::ExcerptHelper.from_html(html)).to eq(text)
  end
end

然后开始摆弄并想出了这个：

def from_html(html)
  Nokogiri::HTML.parse(html).css("p").map{|node|
    node.children.map{|child|
      child.name == "br" ? child.replace(" ") : child
    } << " "
  }.join.strip.gsub(/\s+/, " ")
end

我对 Rails 有点生疏，这可能会更高效、更优雅地完成。我希望在这里得到一些指示。

提前致谢！

方法二

转向sanitize method (thanks @max) and writing a custom scrubber based on Rails::Html::PermitScrubber

方法 3

意识到我的源文档格式为 Markdown，我开始探索自定义 Redcarpet 渲染器。

查看我的以获得完整示例。

Answer 1

我最终写了一个自定义 Redcarpet renderer (inspired by Redcarpet::Render::StripDown)。这似乎是最简洁的方法，格式之间的解析和转换最少。

module R::Markdown
  class ExcerptRenderer < Redcarpet::Render::Base
    # Methods where the first argument is the text content
    [
      # block-level calls
      :paragraph,

      # span-level calls
      :codespan, :double_emphasis,
      :emphasis, :underline, :raw_html,
      :triple_emphasis, :strikethrough,
      :superscript, :highlight, :quote,

      # footnotes
      :footnotes, :footnote_def, :footnote_ref,

      # low level rendering
      :entity, :normal_text
    ].each do |method|
      define_method method do |*args|
        args.first
      end
    end

    # Methods where content is replaced with an empty space
    [
      :autolink, :block_html
    ].each do |method|
      define_method method do |*|
        " "
      end
    end

    # Methods we are going to [snip]
    [
      :list, :image, :table, :block_code
    ].each do |method|
      define_method method do |*|
        " [#{method}] "
      end
    end

    # Other methods
    def link(link, title, content)
      content
    end

    def header(text, header_level)
      " #{text} "
    end

    def block_quote(quote)
      " “#{quote}” "
    end

    # Replace all whitespace with single space
    def postprocess(document)
      document.gsub(/\s+/, " ").strip
    end
  end
end

并解析它：

extensions = {
  autolink:                     true,
  disable_indented_code_blocks: true,
  fenced_code_blocks:           true,
  lax_spacing:                  true,
  no_intra_emphasis:            true,
  strikethrough:                true,
  superscript:                  true,
  tables:                       true
}

markdown = Redcarpet::Markdown.new(R::Markdown::ExcerptRenderer, extensions)

markdown.render(md).html_safe

从 Rails 中的 HTML 个段落创建文本摘录

Create text excerpt from HTML paragraphs in Rails

html

ruby

ruby-on-rails

html-parsing

nokogiri

方法二

方法 3