如何在 Rails 中使用 :through 关联的连接表上设置的条件进行查找？
我有以下模型：
class User < ActiveRecord::Base
has_many :permissions
has_many :tasks, :through => :permissions
class Task < ActiveRecord::Base
has_many :permissions
has_many :users, :through => :permissions
class Permission < ActiveRecord::Base
belongs_to :task
belongs_to :user
我希望能够仅显示用户有权访问的任务（即，在 中将 read 标志设置为 true权限表）。我可以通过以下查询来完成此操作，但对我来说这似乎不太像 Rails-y：
@user = current_user
@tasks = @user.tasks.find_by_sql(["SELECT * FROM tasks INNER JOIN permissions ON tasks.id = permissions.task_id WHERE permissions.read = true AND permissions.user_id = ?", @user.id])
有人知道执行此操作的正确方法吗？
I have the following models:
class User < ActiveRecord::Base
has_many :permissions
has_many :tasks, :through => :permissions
class Task < ActiveRecord::Base
has_many :permissions
has_many :users, :through => :permissions
class Permission < ActiveRecord::Base
belongs_to :task
belongs_to :user
I want to be able to display only tasks which a user has access to (i.e., the read flag is set to true in the Permissions table). I can accomplish this with the following query, but it doesn't seem very Rails-y to me:
@user = current_user
@tasks = @user.tasks.find_by_sql(["SELECT * FROM tasks INNER JOIN permissions ON tasks.id = permissions.task_id WHERE permissions.read = true AND permissions.user_id = ?", @user.id])
Anyone know the right way to do this?
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在这里回答我自己的问题，Rails 实际上允许您在关联本身上设置条件。因此，例如，在我的用户模型中，我会将
has_many关联修改为：非常简洁。 Trip 建议的解决方案也有效（除了，至少对于 MySQL，不应引用“true”）。我发誓我试过了……！
Answering my own question here, Rails actually lets you set conditions on the association itself. So, e.g., in my User model, I'd modify that
has_manyassociation to be:Pretty neat. The solution suggested by Trip also works (except that, for MySQL at least, 'true' should not be quoted). I swear I tried that one...!
抱歉，这是快速猜测。抱歉，如果这不对。
Sorry, this is quick guess. sorry if this isn't right.