Question

我正在运行一个rails 2.3.5 app并获得一个nil：Nilclass在Controller＃show中。

这是我的表演行动

def show
 @category = Category.find_by_url_name(params[:id])
      @brands = @category.brands
      @categories = Category.find(:all)
      @meta_title = "#{@category.name}"

respond_to do |format|
  format.html 
          @brand = @brands.first     
          @search = Product.search.order(params[:order] || 'descend_by_date')

          @products = @search.paginate(:conditions => { :category_id => @category, :brand_id => @brand }, :page => params[:page])      
          render :template => 'brands/show'

  format.xml  { render :xml => @category }
end
end

浏览器跟踪信息：

    /Users/tjs/.rvm/gems/ruby-1.8.7-p352/gems/activesupport-2.3.5/lib/active_support/whiny_nil.rb:52:in `method_missing'
    /Users/tjs/.rvm/gems/ruby-1.8.7-p352/gems/searchlogic-2.5.8/lib/searchlogic/active_record/named_scope_tools.rb:16:in `named_scope_options'
    /Users/tjs/.rvm/gems/ruby-1.8.7-p352/gems/searchlogic-     2.5.8/lib/searchlogic/named_scopes/alias_scope.rb:54:in `named_scope_options'
    /Users/tjs/.rvm/gems/ruby-1.8.7-p352/gems/searchlogic-2.5.8/lib/searchlogic/named_scopes/or_conditions.rb:14:in `named_scope_options'
    /Users/tjs/.rvm/gems/ruby-1.8.7-p352/gems/searchlogic-2.5.8/lib/searchlogic/search/scopes.rb:15:in `scope_options'
    /Users/tjs/.rvm/gems/ruby-1.8.7-p352/gems/searchlogic-2.5.8/lib/searchlogic/search/method_missing.rb:80:in `cast_type'
 /Users/tjs/.rvm/gems/ruby-1.8.7-p352/gems/searchlogic-2.5.8/lib/searchlogic/search/method_missing.rb:22:in `method_missing'
/Users/tjs/.rvm/gems/ruby-1.8.7-p352/gems/searchlogic-2.5.8/lib/searchlogic/search/method_missing.rb:36:in `send'
/Users/tjs/.rvm/gems/ruby-1.8.7-p352/gems/searchlogic-2.5.8/lib/searchlogic/search/method_missing.rb:36:in `method_missing'
/Users/tjs/Sites/emeraldcg/app/controllers/categories_controller.rb:28:in `show'
/Users/tjs/Sites/emeraldcg/app/controllers/categories_controller.rb:25:in `show'

它指向show动作行25和28，第25行是respond_to do | format |

第28行是@search - 产品系列。

更奇怪的是，如果我去编辑类别，则url：/ categories / amps / edit将返回以下内容：

    ActiveRecord::RecordNotFound in CategoriesController#edit

Couldn't find Category with ID=amps
RAILS_ROOT: /Users/tjs/Sites/emeraldcg

Application Trace | Framework Trace | Full Trace
/Users/tjs/.rvm/gems/ruby-1.8.7-p352/gems/activerecord-2.3.5/lib/active_record/base.rb:1586:in `find_one'
/Users/tjs/.rvm/gems/ruby-1.8.7-p352/gems/activerecord-2.3.5/lib/active_record/base.rb:1569:in `find_from_ids'
/Users/tjs/.rvm/gems/ruby-1.8.7-p352/gems/activerecord-2.3.5/lib/active_record/base.rb:616:in `find'
/Users/tjs/Sites/emeraldcg/app/controllers/categories_controller.rb:50:in `edit'

我的分类模型：

class Category < ActiveRecord::Base
  has_many :brands, :through => :products, :uniq => true
  has_many :products
 # acts_as_friendly_param :name

 validates_presence_of :url_name
 validates_uniqueness_of :url_name

 def to_param
  self.url_name
 end
end

这个应用程序在rails 3之前运行良好...非常令人沮丧，我是一个较新的Rails开发人员，所以仍然试图找出如何返回并使用rails 2项目。

任何想法？

Answer 1

您始终可以将@category = Category.find_by_url_name(params[:id])替换为@category = Category.find(:first, :conditions => ["url_name = ?", params[:id]])。

切换到Rails 3.1会更好;）

Answer 2

“找不到ID = amps的类别”是尝试使用id查找记录的查询的结果。例如：

User.find('amps')
will be converted into 
SELECT * FROM users WHERE id='amps';

请确保您使用正确的代码来查找类别。

Answer 3

正如@nkm指出的那样，当您的应用尝试从名为“amps”的ID中搜索类别时会发生此错误

检查您的show url并检查您的routes.rb文件以查看Category是否已配置为Resource

HTH

sameera

Rails 2.3.5为nil获取未定义的方法`to_sym'：NilClass

3 个答案: