Ruby on Rails：SQLite3 :: SQLException：没有这样的列：

Question

SELECT "groups".* FROM "groups"
INNER JOIN "groups_interests" ON "groups"."id" = "groups_interests"."group_id"
WHERE "groups_interests"."interest_id" = 1

SQLite3::SQLException: no such column: groups_interests.interest_id: SELECT "groups".* FROM "groups" INNER JOIN "groups_interests" ON "groups"."id" = "groups_interests"."group_id" WHERE "groups_interests"."interest_id" = 1

ActiveRecord::StatementInvalid: SQLite3::SQLException: no such column: groups_interests.interest_id: SELECT "groups".* FROM "groups" INNER JOIN "groups_interests" ON "groups"."id" = "groups_interests"."group_id" WHERE "groups_interests"."interest_id" = 1

我认为我对外键和has_many关系有误解

为了得到错误，我使用了rails c

Interest.find(1).groups

我也希望此命令正确运行

Groups.find(5).interests

class Group < ActiveRecord::Base
  attr_accessible :description, :name, :project_id
  has_many :students
  has_many :group_interests
  has_many :interests, :through => :group_interests
  belongs_to :project

  validates :name, presence: true, uniqueness: { case_sensitive: false }
end


class Interest < ActiveRecord::Base
  attr_accessible :name

  has_many :group_interests
  has_many :groups, :through => :group_interests

  validates :name, presence: true, uniqueness: { case_sensitive: false }

end

class GroupInterest < ActiveRecord::Base
  attr_accessible :group_id, :interest_id

  belongs_to :groups
  belongs_to :interests

end

我有想法从红宝石在导轨上做到这一点

Answer 1

错误原因：有两种错别字

class GroupInterest < ActiveRecord::Base
  attr_accessible :group_id, :interest_id

  belongs_to :groups      #should be :group
  belongs_to :interests   #should be :interest

end

• Group has_many :group_interests （复数）
• GroupInterest :group （单数）

编辑 -不要使用has_and_belongs_to_many除非您确定您永远不需要关联表中的新属性。 has_many :through更加灵活。

Answer 2

class GroupInterest < ActiveRecord::Base
  attr_accessible :group_id, :interest_id

  belongs_to :group
  belongs_to :interest

end

Group.find(5).interests

Answer 3

为什么不使用has_and_belongs_to_many ：

class Group < ActiveRecord::Base
  attr_accessible :description, :name, :project_id
  has_many :students
  has_and_belongs_to_many :interests
  belongs_to :project
  validates :name, presence: true, uniqueness: { case_sensitive: false }
end


class Interest < ActiveRecord::Base
  attr_accessible :name  
  has_and_belongs_to_many :groups
  validates :name, presence: true, uniqueness: { case_sensitive: false }
end

class GroupInterest < ActiveRecord::Base
  attr_accessible :group_id, :interest_id    
end

您需要在join_table上更改表结构。 请参阅为此提供的链接。