Question

我创建了一个Ruby on Rails作业（从ActiveJob::Base扩展），它解析CSV文件并将其行作为记录（Students）插入数据库中。这是按预期工作的。
但是，当我尝试从数据库中获取另一个对象时（Career为每个Student，每个CSV行的一部分作为一对(career_code, career_name)），我收到此错误：

undefined method 'find_by' for Career:Class

（我也尝试使用Career.where）我发现这很奇怪，因为我已经保存了我的学生，这也是ActiveRecord::Base儿童班。

这是我工作的相关部分：

ActiveRecord::Base.transaction do
        student_hash.keys.each do |k|
        some_student = student_hash[k]
        student = Student.new
        student.csv_id = some_student.id
        student.first_name = some_student.first_name
        student.last_name = some_student.last_name
        student.file_number = some_student.file_number
        # student.career = Career.where(code: some_student.career_code)
        student.career = Career.find_by code: some_student.career_code
        puts student.save!  # Why this works, and the above line doesn't?
    end
end

而且，正如我在Rails控制台中看到的那样，所需的输出：

Loading development environment (Rails 4.2.4.rc1)
2.1.3 :001 > Career.where(code: 11)
  Career Load (0.5ms)  SELECT "careers".* FROM "careers" WHERE "careers"."code" = ?  [["code", 11]]
 => #<ActiveRecord::Relation [#<Career id: 4, name: "Informática", created_at: "2015-09-30 22:05:07", updated_at: "2015-09-30 22:05:07", code: 11>]> 
2.1.3 :002 > Career.where code: 11
  Career Load (0.2ms)  SELECT "careers".* FROM "careers" WHERE "careers"."code" = ?  [["code", 11]]
 => #<ActiveRecord::Relation [#<Career id: 4, name: "Informática", created_at: "2015-09-30 22:05:07", updated_at: "2015-09-30 22:05:07", code: 11>]> 
2.1.3 :003 > Career.find_by code: 11
  Career Load (0.4ms)  SELECT  "careers".* FROM "careers" WHERE "careers"."code" = ? LIMIT 1  [["code", 11]]
 => #<Career id: 4, name: "Informática", created_at: "2015-09-30 22:05:07", updated_at: "2015-09-30 22:05:07", code: 11> 
2.1.3 :004 >

这可能是一个非常愚蠢的问题，但我是一个使用Rails的初学者。我是否需要导入某种“上下文”（这似乎不太可能，因为学生似乎得到了妥善解决）？顺便说一句，我正在使用Rails 4.2.4.rc1 提前致谢

Answer 1

代码职业生涯中任何机会都不是AR，而是其他一些课程？这至少可以解释为什么这些方法不存在。

无法在Rails作业中找到数据库中的对象

1 个答案: