如何按類別篩選條目...範圍或其他方式？

Question

如何通過類別過濾條目？

我webscrapping reddit的教育目的，只刮他們的標題，鏈接和類別。

這裏是它通過lib目錄代碼：嘗試如何在index.html.erb，但在虧損過濾此

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 

。

決定嘗試範圍，即使我以前從未寫過。

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 

範圍將範圍上的索引行動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 

收到此錯誤信息，指出：

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

，它的參考到範圍。

我該如何解決這個問題，或者通過分類篩選項，如果有一個不同的方式去做，而不是作用域。

在此先感謝，並請讓我知道是否需要額外的數據。

輸出

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

的樣本您不要在這裏需要一個範圍，他們清理where條款。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 

，這將創造這樣一個哈希：

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

然後在視圖中可以

在刮板

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

你的第二個問題不處理重複：

更改：

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

到：

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