Rails的：ActiveRecord的:: StatementInvalid在

Question

我試圖讓所有的活動（belongs_to的：學生）相關的學生

@activities = Activity.joins(:student).where(student: {student_id: @student.id}) 

但是我越來越：在我的控制器使用這個（的has_many活動）這是一個錯誤：

SQLite3::SQLException: no such column: student.student_id: SELECT "activities".* FROM "activities" INNER JOIN "students" ON "students"."id" = "activities"."student_id" WHERE "student"."student_id" = ?

Answer 1

是否有一個理由，爲什麼你不能做到這一點？：

@activities = @student.activities 

你Student類應該是這樣的：

class Student < ActiveRecord::Base 

    has_many :activities 

end 

如果你想能夠訪問t他直接從Activity類的學生活動，我建議使用範圍代替。像這樣的東西應該工作：

class Activity < ActiveRecord::Base 

    scope :for_student, ->(student) { where(student_id: student) } 

end 

您可以使用範圍在幾個不同的方式：

# pass in the student directly 
@activities = Activity.for_student(@student) 

# pass in the student id 
@activities = Activity.for_student(@student.id) 

# pass in many students 
@activities = Activity.for_student([@student1, @student2]) 

Answer 2

嘗試刪除學生的前綴：

@activities = Activity.joins(:student).where(student: {id: @student.id}) 

它說，它CA沒有在表student上找到列student_id。

Answer 3

@activities = Activity.where(student_id: @student.id) 

或

@activities = @student.activities