简单的关联在Heroku上不起作用

Question

我有一个正在部署到Heroku的应用程序。对于我的用户模型，除了"show“操作之外，似乎所有的东西都能正常工作。

下面是我为用户模型编写的代码(不管怎样，什么是相关的)

class User < ActiveRecord::Base

  attr_accessor :password
  attr_accessible :username, :email, :password, 
                  :password_confirmation, :confirmed, 
                  :school_id, :graduation, 
                  :admin, :stars, :credits, :school_name

  has_many :uploads, :dependent => :destroy
  belongs_to :school
  has_many :downloads, :source => :user_id, :dependent => :destroy
  has_many :comments, :dependent => :destroy

  #VALIDATIONS OMITTED

  #WARNING
  before_create :encrypt_password

  #PASSWORD ENCRYPTION METHOD OMITTED

  #getter for school name
  def school_name
    school.name if school
  end

  #setter for school name (will create school if it didn't find one)
  def school_name=(name)
    self.school = School.find_by_name(name) unless name.blank?
  end

  def add_credits(num)
    self.credits += num
  end

  def charge
    self.credits -= 1
    self.save(false)
  end

  def has_downloaded?(file)
    @downloads = self.downloads.find(:all, :conditions => "upload_id = #{file.id}")
    return (@downloads.length > 0)
  end


  private

    #MORE PASSWORD ENCRYPTION LOGIC

end

下面是我的上传模型的代码：

class Upload < ActiveRecord::Base
    default_scope :order => 'uploads.created_at DESC'

    attr_protected :linked_file_name, :linked_content_type, :linked_size

    attr_accessible :user_id, :stars, :ratings, 
                    :semester, :professor, :year, 
                    :description, :course_id, :school_id

    after_save :set_course_school

    belongs_to :user
    belongs_to :school
    belongs_to :course
    has_many :downloads, :source => :upload_id, :dependent => :destroy
    has_many :comments, :foreign_key => "file_id", :dependent => :destroy
    #belongs_to :class

    #paperclip
    has_attached_file :linked,
          :storage => :s3,
          :s3_credentials => "#{RAILS_ROOT}/config/s3.yml",
          :path => ":class/:id/:attachment/:basename.:extension"

    #validations
    validates :school_id, :presence => true

    def update_rating
      @comments = self.comments.all
      if @comments.length > 0
        @stars = 0
        @comments.each do |comment|
          @stars += comment.rating
        end
        self.stars = @stars
        self.ratings = @comments.length
      end
      self.save(false)
    end

    def course_name
      return [course.subject, course.course_code].join(' ') if course
    end

    def course_name=(name)
      @split = name.split(' ', 2)
      @subject = @split.first
      @course_code = @split.last

      @conditions = {
        :subject => @subject,
        :course_code => @course_code,
        :school_id => self.school_id
      }

      self.course = Course.find(:first, :conditions => @conditions) || Course.create(@conditions)
    end

    def set_course_school
      course.set_school
    end

end

下面是控制器的操作：

  def show
    @user = User.find(params[:id])
    @uploads = @user.uploads.all
    @downloads = @user.downloads.all
  end

Heroku似乎对语句@user.uploads.all有一些问题，它在本地工作得很好，以下是日志给我的：

2011-12-29T21:57:07+00:00 app[web.1]: Started GET "/users/1" for 200.88.103.28 at 2011-12-29 13:57:07 -0800
2011-12-29T21:57:07+00:00 app[web.1]:   Processing by UsersController#show as HTML
2011-12-29T21:57:07+00:00 app[web.1]:   Parameters: {"id"=>"1"}
2011-12-29T21:57:07+00:00 app[web.1]: Completed   in 10ms
2011-12-29T21:57:07+00:00 app[web.1]: 
2011-12-29T21:57:07+00:00 app[web.1]: ActiveRecord::StatementInvalid (PGError: ERROR:  operator does not exist: character varying = integer
2011-12-29T21:57:07+00:00 app[web.1]: : SELECT     "uploads".* FROM       "uploads"  WHERE     ("uploads".user_id = 1) ORDER BY  uploads.created_at DESC):
2011-12-29T21:57:07+00:00 app[web.1]:                                                              ^
2011-12-29T21:57:07+00:00 app[web.1]:   app/controllers/users_controller.rb:21:in `show'
2011-12-29T21:57:07+00:00 app[web.1]: HINT:  No operator matches the given name and argument type(s). You might need to add explicit type casts.
2011-12-29T21:57:07+00:00 app[web.1]: LINE 1: ...ROM       "uploads"  WHERE     ("uploads".user_id = 1) ORDER...

有什么想法吗？我想解决这个问题非常简单。奇怪的是，我有另一个Heroku部署的应用程序，它使用完全相同的用户逻辑(有一个显示页面，可以获取用户的所有“帖子”)，而且工作得很好。代码看起来几乎一样..。

我非常感谢这个问题的解决方案。我希望我能提供一笔赏金，但我在一个Android问题上花了我大部分的时间在悬赏上。

Answer 1

从错误语句中可以看出，uploads表中的user_id列是一个varchar，而不是整数。据我所知，Postgres (Heroku使用的)不会自动强制转换。

你能确认数据类型吗？