如何按类别筛选条目...范围或其他方式？

Question

如何通过类别过滤条目？

我webscrapping reddit的教育目的，只刮他们的标题，链接和类别。

这里是它通过lib目录代码：尝试如何在index.html.erb，但在亏损过滤此

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 

。

决定尝试范围，即使我以前从未写过。

下面是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 

范围将范围上的索引行动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 

收到此错误信息，指出：

ArgumentError in EntriesController#index 
wrong number of arguments (given 0, expected 1) 

，它的参考到范围。

我该如何解决这个问题，或者通过分类筛选项，如果有一个不同的方式去做，而不是作用域。

在此先感谢，并请让我知道是否需要额外的数据。

输出

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/ 

Answer 1

的样本您不要在这里需要一个范围，他们清理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 

，这将创造这样一个哈希：

{ 
    "category1" => [Entry,Entry,Entry], 
    "category2" => [Entry], 
    ... 
} 

然后在视图中可以

在刮板

<% @entries.each do |category, entries| %> 
    <h1><%= category %></h1> 
    <% entries.each do |entry| %> 
    <p><%= entry.inspect %></p> 
    <% end %> 
<% end %> 

你的第二个问题不处理重复：

更改：

Entry.create!(title: title, link: link, category: category) 

到：

Entry.where(title: title, link: link, category: category).first_or_create