ROR + Ransack：根据数字范围（年龄类别）筛选结果

Question

我试图按照使用Ransack的年龄类别来允许筛选条件。但是，我没有将年龄段作为文章表的一部分，而是作为文章模型中的一种方法。我已经参考了这个

我希望用户能够过滤具有属于年龄段的created_at日期的文章，但是，我似乎无法理解为什么选择年龄段的options_for_select列表根本没有被呈现。当我检查轨道控制台时，div标记之间没有内容。

但是，呈现了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 

编辑：我固定它通过添加=之后<％呈现字段。我现在正在得到一个新的错误，似乎Ransacker语法存在问题。

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... 

当我测试改变parent.table[:created_at]到parent.table[:age_group]，我得到这个错误，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

您可以创建一个ransacker像这样

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 

，然后在视图中更改:age_group_in到:age_group_eq。如果您使用类似MSSQL之类的东西，则此答案假定为postgres，那么CASE药水简化为DATEDIFF(m,#{parent.table[:created_at]},GETDATE())。

这种缺乏日常的准确性，但我认为这是为您的使用足够接近