簡單的關聯在Heroku上不起作用

Question

我有一個應用程序，我正在部署到Heroku。除了我的用戶模型的「顯示」操作之外，一切似乎都奏效。

這裏是我的用戶模型代碼（什麼是相關的，反正）

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 

這裏是我上傳的型號代碼：

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 

這裏是控制器動作：

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

Heroku似乎有一些問題與@user.uploads.all聲明工作正常在本地，這裏是日誌給我的東西：

2011-12-29T21:57:07+00:00 app[web.1]: Started GET "https://stackoverflow.com/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... 

任何想法？我想這個解決方案非常簡單。有什麼奇怪的是，我有另一個Heroku部署的應用程序使用完全相同的用戶邏輯（有一個顯示頁面，可以獲取用戶的所有'帖子'），並且工作正常。代碼看起來幾乎相同...

我非常感謝解決這個問題。我希望我可以提供賞金，但是我在Android問題上用了大部分代幣。

Answer 1

從錯誤語句看起來，uploads表中的user_id列是varchar，而不是整數。就我所知，Postgres（由Heroku使用）不會自動投射。

你能確認數據類型嗎？