如何獲得Collection對象通過量很多，以on Rails的

朋友在Ruby中的許多關係，我下面的模型如何獲得Collection對象通過量很多，以on Rails的

class Project < ActiveRecord::Base 
    has_many :milestones_projects 
    has_many :milestones, :through => :milestones_projects 
    validates :projectname, :presence=>true, :length=> {:maximum=>250}, :uniqueness=>true 
    validates :location,:presence=>true 
end 

class Milestone < ActiveRecord::Base 
    has_many :milestones_projects 
    has_many :projects, :through => :milestones_projects 

    validates :name, :presence => true, :length => {:maximum => 250} 
    validates :days, :presence => true, :length => {:maximum => 3} 
    validates :stage, :presence => true 
end 


class MilestonesProjects < ActiveRecord::Base 
    belongs_to :milestones,:foreign_key => 'milestone_id' 
    belongs_to :projects,:foreign_key => 'project_id' 
end

所以我有很多對許多項目和里程碑之間的關係。

在IRB，我想收集的對象，所以我用如下

irb(main):001:0> me=Project.find(1) 
=> #<Project id: 1, location_id: 1, projectname: "Sample 2", description: "Sample 2", i 
spublished: true, created_at: "2011-09-02 08:26:41", updated_at: "2011-09-07 10:26:48">

這裏「我」是一個數組包含的第一個項目的細節，現在我「試圖讓里程碑細節。與此項目有關此我想如下

irb(main):002:0> me.milestones

，但它給我的錯誤，如

NameError：未初始化的常量項目:: MilestonesProject from c：/RailsInstaller/Ruby1.8.7/lib/ruby/gems/1.8/gems/activerecord-3.0.9/lib/ active_record/base.rb：1205：in compute_type' from c:/RailsInstaller/Ruby1.8.7/lib/ruby/gems/1.8/gems/activerecord-3.0.9/lib/ active_record/reflection.rb:162:in send' from c：/ RailsInstaller/Ruby1 .8.7/lib/ruby/gems/1.8/gems/activerecord-3.0.9/lib/ active_record/reflection.rb：162：in klass' from c:/RailsInstaller/Ruby1.8.7/lib/ruby/gems/1.8/gems/activerecord-3.0.9/lib/ active_record/reflection.rb:346:in source_reflection' from c：/RailsInstaller/Ruby1.8.7/lib/ruby/gems /1.8/gems/activerecord-3.0.9/lib/ active_record/reflection.rb：346：collect' from c:/RailsInstaller/Ruby1.8.7/lib/ruby/gems/1.8/gems/activerecord-3.0.9/lib/ active_record/reflection.rb:346:in source_reflection' from c：/RailsInstaller/Ruby1.8.7/lib/ruby/gems/1.8/gems/activerecord-3.0 .9/lib/ active_record/reflection.rb：377：在check_validity!' from c:/RailsInstaller/Ruby1.8.7/lib/ruby/gems/1.8/gems/activerecord-3.0.9/lib/ active_record/associations/association_proxy.rb:61:in中初始化' from c：/RailsInstaller/Ruby1.8.7/lib/ruby/gems/1.8/gems/activerecord-3.0.9/lib/ active_record/associations/association_collection.rb：23：在initialize' from c:/RailsInstaller/Ruby1.8.7/lib/ruby/gems/1.8/gems/activerecord-3.0.9/lib/ active_record/associations/has_many_association.rb:11:in中初始化' from c：/RailsInstaller/Ruby1.8.7/lib/ruby/gems/1.8/gems/activerecord-3.0.9/lib/ active_record/associations.rb ：1483：從（IRB）在new' from c:/RailsInstaller/Ruby1.8.7/lib/ruby/gems/1.8/gems/activerecord-3.0.9/lib/ active_record/associations.rb:1483:in里程碑：2 來自：0

所以朋友們請幫我..

我需要執行像

milestone_count=project.milestones.size

來源

2011-09-17 Shreekumar S

你可以添加你的Rails項目（含里程碑，項目的一部分的模式，和milestone_projects）。你可以編輯你的文章，以便堆棧跟蹤縮進4個空格嗎？ – mliebelt

感謝您的快速反應！最後我找到了解決辦法，都在這裏張貼的答案是正確的..

我改變了我的模特這樣

class Project < ActiveRecord::Base 
    has_many :project_milestones 
    has_many :milestones, :through => :project_milestones 
end 

class Milestone < ActiveRecord::Base 
    has_many :project_milestones 
    has_many :projects, :through => :project_milestones 
end 

class ProjectMilestone < ActiveRecord::Base 
    belongs_to :milestone,:foreign_key => 'milestone_id' 
    belongs_to :project,:foreign_key => 'project_id' 
end

來源

2011-09-18 11:19:39

我懷疑某些命令命名約定鐵軌是這裏的問題。 Rails認爲你的模型對象是單數的，你的數據庫表格是複數。 Rails在名爲MilestonesProjects的模型中可能有問題，因此應將其命名爲MilestoneProject，因爲它是：Milestone和Project之間的關係。看看"Guide to Active Records"第2.4節中的例子，以及使用單數和複數的例子。

來源

2011-09-17 08:38:02 mliebelt

試試這個代碼在你MilestonesProjects模型

class MilestonesProjects < ActiveRecord::Base 
    belongs_to :milestone,:foreign_key => 'milestone_id' 
    belongs_to :project,:foreign_key => 'project_id' 
end

來源

2011-09-17 13:09:20

如何獲得Collection對象通過量很多，以on Rails的

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