ROR + Ransack：根據數字範圍（年齡類別）篩選結果

Question

我試圖按照使用Ransack的年齡類別來允許篩選條件。但是，我沒有將年齡段作爲文章表的一部分，而是作爲文章模型中的一種方法。我已經參考了這個

我希望用戶能夠過濾具有屬於年齡段的created_at日期的文章，但是，我似乎無法理解爲什麼選擇年齡段的options_for_select列表根本沒有被呈現。當我檢查軌道控制檯時，div標記之間沒有內容。

但是，呈現了options_from_collection_for_select的下拉列表。

模式：

create_table "articles", force: :cascade do |t| 
    t.string "title" 
    t.text "description" 
    t.bigint "user_id" 
    t.datetime "created_at", null: false 
    t.datetime "updated_at", null: false 
    end 

browse.html.erb

<div class="form-group"> 
    <div class ="row"> 
    <div class="col-md-6 col-sm-6 col-xs-6"> 
     <%= f.select :categories_name_cont, options_from_collection_for_select(Category.all, "id", "name", @q.categories_name_eq), 
                      { :prompt => "Any Category" }, 
                      { class: "form-control" } %> 
    </div> 
    <div class="col-md-6 col-sm-6 col-xs-6"> 
     <% f.select :age_group_in, options_for_select([["more than 1 year ago", "more than 1 year ago"], 
                ["less than 1 year ago", "less than 1 year ago"], 
                ["less than 3 months ago", "less than 3 months ago"], 
                ["less than 1 month ago", "less than 1 month ago"]]), 
                { :prompt => "Any Age Group" }, 
                { class: "form-control" } %> 
    </div> 
    </div> 
</div> 

文章控制器

def browse 
    @q = Article.ransack(params[:q]) 
    @articles_morefilter = @q.result.includes(:categories, :users) 
end 

模型：article.rb

def age_group 
    months_between = Date.today.month - self.created_at.month 
    if months_between > 12 
     "more than 1 year ago" 
    elsif months_between <= 12 
     "less than 1 year ago" 
    elsif months_between <= 3 
     "less than 3 months ago" 
    elsif months_between <= 1 
     "less than 1 month ago" 
    end 
    end 

ransacker :age_group, :formatter => proc {|v| Date.today.month - v.created_at.month} do |parent| 
    parent.table[:created_at] 
end 

編輯：我固定它通過添加=之後<％呈現字段。我現在正在得到一個新的錯誤，似乎Ransacker語法存在問題。

PG::InvalidDatetimeFormat: ERROR: invalid input syntax for type timestamp: "less than 1 month ago" 
LINE 1: ...name" ILIKE '%1%' AND "articles"."created_at" IN ('less than... 

當我測試改變parent.table[:created_at]到parent.table[:age_group]，我得到這個錯誤，而不是：

PG::UndefinedColumn: ERROR: column articles.age_group does not exist 
LINE 1: ...ry_id" WHERE ("categories"."name" ILIKE '%3%' AND "articles"... 

Answer 1

您可以創建一個ransacker像這樣

class Article < ApplicationRecord 

    ransacker :age_group do |parent| 
    query= <<-SQL 
     CASE ((DATE_PART('year', CURRENT_DATE) - DATE_PART('year', #{parent.table[:created_at].to_sql})) * 12 + 
      (DATE_PART('month', CURRENT_DATE) - DATE_PART('month', #{parent.table[:created_at].to_sql}))) 
     WHEN 0,1 THEN "less than 1 month ago" 
     WHEN 2,3 THEN "less than 3 months ago" 
     WHEN 4,5,6,7,8,9,10,11,12 THEN "less than 1 year ago" 
     ELSE "more than 1 year ago" 
     END 
    SQL 
    Arel.sql(query) 
    end 

，然後在視圖中更改:age_group_in到:age_group_eq。如果您使用類似MSSQL之類的東西，則此答案假定爲postgres，那麼CASE藥水簡化爲DATEDIFF(m,#{parent.table[:created_at]},GETDATE())。

這種缺乏日常的準確性，但我認爲這是爲您的使用足夠接近