轨HAS_ONE创建错误

Question

进展：

#== Schema Information 
# 
# Table name: progresses 
# 
# id   :integer   not null, primary key 
# width  :integer   default(0) 
# course_id :integer   not null 
# created_at :datetime  not null 
# updated_at :datetime  not null 
# 

class Progress < ActiveRecord::Base 
    has_many:progress_comments 
    belongs_to:course 
end 

课程：

# == Schema Information 
# 
# Table name: courses 
# 
# id   :integer   not null, primary key 
# courseName :string(50)  not null 
# place  :string(100)  not null 
# startTime :datetime  default(2012-02-10 00:39:52 UTC) 
# endTime :datetime 
# teacher :string(20)  default("nil_teacher") 
# reason  :text   not null 
# upNum  :integer   default(0) 
# downNum :integer   default(0) 
# day  :integer   not null 
# school_id :integer   not null 
# created_at :datetime  not null 
# updated_at :datetime  not null 
# 

class Course < ActiveRecord::Base 
    #attr_acessssible: 
    #validates :courseName, presence: true 
    has_many:remarks 
    has_many:reviews 
    has_one:progress 
    has_and_belongs_to_many:course_catagories 
    belongs_to:school 
end 

，而我想创建由
Course.first.progress.create(...)
它出现在铁轨控制台进度：
undefined method 'create' for nil:NilClass
任何人得到一些想法？谢谢

Answer 1

尝试使用Course.first.create_progress(...); progress.create格式适用于多个关联，如has_many。