如何通过类别过滤我的条目？
我正在为了教育目的而使用reddit进行网页抓取，只抓取他们的标题，链接和类别。
以下是通过lib目录的代码：
require 'open-uri'
module RedditScrapper
def self.scrape
doc = Nokogiri::HTML(open("https://www.reddit.com/"))
entries = doc.css('.entry')
entries.each do |entry|
title = entry.css('p.title > a').text
link = entry.css('p.title > a')[0]['href']
category = entry.css('p.tagline > a.subreddit')[0]['href']
Entry.create!(title: title, link: link, category: category )
end
end
end
尝试在index.html.erb中对此进行过滤，但不知道如何。
决定尝试范围，即使我之前从未写过。
这是Entry模型
class Entry < ApplicationRecord
validates :title, presence: true
validates :link, presence: true
validates :category, presence: true
scope :categorization, -> (category) { where category: category }
end
将范围放在entries_controller
class EntriesController < ApplicationController
def index
@entries = Entry.all
@entries = @entries.categorization
end
def scrape
RedditScrapper.scrape
respond_to do |format|
format.html { redirect_to entries_url, notice: 'Entries were successfully scraped.' }
format.json { entriesArray.to_json }
end
end
end
收到此错误消息，说明：
ArgumentError in EntriesController#index
wrong number of arguments (given 0, expected 1)
并且它参考了范围。
如何修复此问题，或者按类别过滤条目，如果有不同的方式而不是范围。
提前致谢，如果需要其他数据，请告诉我。
输出样本
LifeProTips
LPT: if you're in a bad mood or something has annoyed you, be as kind as you can to the next 3 people you encounter. By not reacting to the bad mood, as well as helping others, you'll feel miles better.
/r/LifeProTips/comments/5zf0l2/lpt_if_youre_in_a_bad_mood_or_something_has/
LPT: if you're in a bad mood or something has annoyed you, be as kind as you can to the next 3 people you encounter. By not reacting to the bad mood, as well as helping others, you'll feel miles better.
/r/LifeProTips/comments/5zf0l2/lpt_if_youre_in_a_bad_mood_or_something_has/
LPT: if you're in a bad mood or something has annoyed you, be as kind as you can to the next 3 people you encounter. By not reacting to the bad mood, as well as helping others, you'll feel miles better.
/r/LifeProTips/comments/5zf0l2/lpt_if_youre_in_a_bad_mood_or_something_has/
LPT: if you're in a bad mood or something has annoyed you, be as kind as you can to the next 3 people you encounter. By not reacting to the bad mood, as well as helping others, you'll feel miles better.
/r/LifeProTips/comments/5zf0l2/lpt_if_youre_in_a_bad_mood_or_something_has/
LPT: if you're in a bad mood or something has annoyed you, be as kind as you can to the next 3 people you encounter. By not reacting to the bad mood, as well as helping others, you'll feel miles better.
/r/LifeProTips/comments/5zf0l2/lpt_if_youre_in_a_bad_mood_or_something_has/
LPT: if you're in a bad mood or something has annoyed you, be as kind as you can to the next 3 people you encounter. By not reacting to the bad mood, as well as helping others, you'll feel miles better.
/r/LifeProTips/comments/5zf0l2/lpt_if_youre_in_a_bad_mood_or_something_has/
LPT: if you're in a bad mood or something has annoyed you, be as kind as you can to the next 3 people you encounter. By not reacting to the bad mood, as well as helping others, you'll feel miles better.
/r/LifeProTips/comments/5zf0l2/lpt_if_youre_in_a_bad_mood_or_something_has/
LPT: if you're in a bad mood or something has annoyed you, be as kind as you can to the next 3 people you encounter. By not reacting to the bad mood, as well as helping others, you'll feel miles better.
/r/LifeProTips/comments/5zf0l2/lpt_if_youre_in_a_bad_mood_or_something_has/
LPT: if you're in a bad mood or something has annoyed you, be as kind as you can to the next 3 people you encounter. By not reacting to the bad mood, as well as helping others, you'll feel miles better.
/r/LifeProTips/comments/5zf0l2/lpt_if_youre_in_a_bad_mood_or_something_has/
LPT: if you're in a bad mood or something has annoyed you, be as kind as you can to the next 3 people you encounter. By not reacting to the bad mood, as well as helping others, you'll feel miles better.
/r/LifeProTips/comments/5zf0l2/lpt_if_youre_in_a_bad_mood_or_something_has/
LPT: if you're in a bad mood or something has annoyed you, be as kind as you can to the next 3 people you encounter. By not reacting to the bad mood, as well as helping others, you'll feel miles better.
/r/LifeProTips/comments/5zf0l2/lpt_if_youre_in_a_bad_mood_or_something_has/
LPT: if you're in a bad mood or something has annoyed you, be as kind as you can to the next 3 people you encounter. By not reacting to the bad mood, as well as helping others, you'll feel miles better.
/r/LifeProTips/comments/5zf0l2/lpt_if_youre_in_a_bad_mood_or_something_has/
LPT: if you're in a bad mood or something has annoyed you, be as kind as you can to the next 3 people you encounter. By not reacting to the bad mood, as well as helping others, you'll feel miles better.
/r/LifeProTips/comments/5zf0l2/lpt_if_youre_in_a_bad_mood_or_something_has/
LPT: if you're in a bad mood or something has annoyed you, be as kind as you can to the next 3 people you encounter. By not reacting to the bad mood, as well as helping others, you'll feel miles better.
/r/LifeProTips/comments/5zf0l2/lpt_if_youre_in_a_bad_mood_or_something_has/
LPT: if you're in a bad mood or something has annoyed you, be as kind as you can to the next 3 people you encounter. By not reacting to the bad mood, as well as helping others, you'll feel miles better.
/r/LifeProTips/comments/5zf0l2/lpt_if_youre_in_a_bad_mood_or_something_has/
LPT: if you're in a bad mood or something has annoyed you, be as kind as you can to the next 3 people you encounter. By not reacting to the bad mood, as well as helping others, you'll feel miles better.
/r/LifeProTips/comments/5zf0l2/lpt_if_youre_in_a_bad_mood_or_something_has/
LPT: if you're in a bad mood or something has annoyed you, be as kind as you can to the next 3 people you encounter. By not reacting to the bad mood, as well as helping others, you'll feel miles better.
/r/LifeProTips/comments/5zf0l2/lpt_if_youre_in_a_bad_mood_or_something_has/
LPT: if you're in a bad mood or something has annoyed you, be as kind as you can to the next 3 people you encounter. By not reacting to the bad mood, as well as helping others, you'll feel miles better.
/r/LifeProTips/comments/5zf0l2/lpt_if_youre_in_a_bad_mood_or_something_has/
LPT: if you're in a bad mood or something has annoyed you, be as kind as you can to the next 3 people you encounter. By not reacting to the bad mood, as well as helping others, you'll feel miles better.
/r/LifeProTips/comments/5zf0l2/lpt_if_youre_in_a_bad_mood_or_something_has/
LPT: if you're in a bad mood or something has annoyed you, be as kind as you can to the next 3 people you encounter. By not reacting to the bad mood, as well as helping others, you'll feel miles better.
/r/LifeProTips/comments/5zf0l2/lpt_if_youre_in_a_bad_mood_or_something_has/
LPT: if you're in a bad mood or something has annoyed you, be as kind as you can to the next 3 people you encounter. By not reacting to the bad mood, as well as helping others, you'll feel miles better.
/r/LifeProTips/comments/5zf0l2/lpt_if_youre_in_a_bad_mood_or_something_has/
LPT: if you're in a bad mood or something has annoyed you, be as kind as you can to the next 3 people you encounter. By not reacting to the bad mood, as well as helping others, you'll feel miles better.
/r/LifeProTips/comments/5zf0l2/lpt_if_youre_in_a_bad_mood_or_something_has/
LPT: if you're in a bad mood or something has annoyed you, be as kind as you can to the next 3 people you encounter. By not reacting to the bad mood, as well as helping others, you'll feel miles better.
/r/LifeProTips/comments/5zf0l2/lpt_if_youre_in_a_bad_mood_or_something_has/
LPT: if you're in a bad mood or something has annoyed you, be as kind as you can to the next 3 people you encounter. By not reacting to the bad mood, as well as helping others, you'll feel miles better.
/r/LifeProTips/comments/5zf0l2/lpt_if_youre_in_a_bad_mood_or_something_has/
LPT: if you're in a bad mood or something has annoyed you, be as kind as you can to the next 3 people you encounter. By not reacting to the bad mood, as well as helping others, you'll feel miles better.
/r/LifeProTips/comments/5zf0l2/lpt_if_youre_in_a_bad_mood_or_something_has/
LPT: if you're in a bad mood or something has annoyed you, be as kind as you can to the next 3 people you encounter. By not reacting to the bad mood, as well as helping others, you'll feel miles better.
/r/LifeProTips/comments/5zf0l2/lpt_if_youre_in_a_bad_mood_or_something_has/
答案 0 :(得分：1)
您不需要这里的范围，它们用于清理where条款。只需使用group_by
def index
@entries = Entry.all.group_by{ |entry| entry.category }
# a shorter more ruby way of writing this is:
# @entries = Entry.all.group_by(&:category)
end
将创建这样的哈希：
{
"category1" => [Entry,Entry,Entry],
"category2" => [Entry],
...
}
然后在你看来你可以
<% @entries.each do |category, entries| %>
<h1><%= category %></h1>
<% entries.each do |entry| %>
<p><%= entry.inspect %></p>
<% end %>
<% end %>
你的第二个问题是没有处理刮刀中的重复：
变化：
Entry.create!(title: title, link: link, category: category)
到：
Entry.where(title: title, link: link, category: category).first_or_create