Ruby on Rails:提前搜索，未定义方法[]为nil: nil类

Question

我对rails非常陌生，并尝试使一个先进的搜索表单，它需要两个值'blood_group'和'area'，并基于该搜索从数据库中获取记录，并将显示在同一页面上(find.html.erb)我在find.html.erb中尝试了一些东西，但是出现了一个错误"未定义的方法[]for nil: nil类"，其中我的搜索表单存在。请帮忙解决这个错误。

这是我在find.html.erb中的搜索表单

<%= form_tag find_path , method: :get do %>
             <p> <%= label_tag :blood_group %><br />
              <%= select_tag (:blood_group), options_for_select(%w[ A+ B+ O+ AB+ A- B- O- AB-]), params[:blood_group] %> </p>
             <p> <%= label_tag :area %><br />
              <%= select_tag (:area), options_for_select(%w[Indore Vijay_Nagar Bhawar_Kuwa Rajendra_Nagar Geeta_Bhawan Aerodram Tejaji_Nagar Raj_Mohalla Rajwada Chandan_Nagar Gandhi_Nagar Arvindo MY Bombay_Hospital]) , params[:area] %> </p> 

              <%= submit_tag "Search" , class: "btn btn-primary" , name: nil %>
            <% end %>

错误出现在我使用select标记的行。下面是我在捐赠者控制器

中的查找操作

def find
    @donors = Donor.search(params[:blood_group], params[:area]).all 
 end

和捐助。Rb如下

class Donor < ActiveRecord::Base

def self.search(blood_group, area)
    return all unless blood_group.present? || area.present?
    where(['blood_group LIKE ? AND area LIKE ?', "%#{blood_group}%", "%#{area}%"])
end

结束

Answer 1

您的搜索表单必须是这样的:

<%= form_tag find_path , method: :get, remote: true do %>
         <p> <%= label_tag :blood_group %><br />
          <%= select_tag (:blood_group), options_for_select(%w[ A+ B+ O+ AB+ A- B- O- AB-]) %> </p>
         <p> <%= label_tag :area %><br />
          <%= select_tag (:area), options_for_select(%w[Indore Vijay_Nagar Bhawar_Kuwa Rajendra_Nagar Geeta_Bhawan Aerodram Tejaji_Nagar Raj_Mohalla Rajwada Chandan_Nagar Gandhi_Nagar Arvindo MY Bombay_Hospital]) %> </p> 

          <%= submit_tag "Search" , class: "btn btn-primary" , name: nil %>
        <% end %>

将控制器修改为:

def find
  @donors = Donor.search(params[:blood_group], params[:area]).all 
  respond_to do |format|
    format.js
  end
end

然后添加find.js.erb显示搜索的内容