has_and_belongs_to_many 查询在一个方向有效，在另一个方向失败
我有：
class Service < ActiveRecord::Base
has_and_belongs_to_many :staffs
并且
class Staff < ActiveRecord::Base
has_and_belongs_to_many :services
使用带有列 services_id 和 Staffs_id 的中间表 services_staffs
以下查询成功：
Staff.find( :all, :conditions => "service_id = #{service_id}" )
但另一个方向失败：
Service.find( :all, :conditions => "staff_id = #{staff_id}" )
使用
服务负载（0.3ms） SELECT "services".*, t0.staff_id as the_parent_record_id FROM "services" INNER JOIN "services_staffs" t0 ON "services".id = t0.service_id WHERE (t0.staff_id IN (12,13,14)) 服务负载 (0.0ms) SQLite3::SQLException: 没有这样的列：staff_id: SELECT * FROM " services" WHERE (staff_id = 13)
ActiveRecord::StatementInvalid (SQLite3::SQLException: 没有这样的列：staff_id: SELECT * FROM "services" WHERE (staff_id = 13) ):
知道为什么吗？
I have:
class Service < ActiveRecord::Base
has_and_belongs_to_many :staffs
and
class Staff < ActiveRecord::Base
has_and_belongs_to_many :services
With the intermediate table services_staffs with columns services_id and staffs_id
The following query succeeds:
Staff.find( :all, :conditions => "service_id = #{service_id}" )
But going the other direction fails:
Service.find( :all, :conditions => "staff_id = #{staff_id}" )
with
Service Load (0.3ms) SELECT "services".*, t0.staff_id as the_parent_record_id FROM "services" INNER JOIN "services_staffs" t0 ON "services".id = t0.service_id WHERE (t0.staff_id IN (12,13,14)) Service Load (0.0ms) SQLite3::SQLException: no such column: staff_id: SELECT * FROM "services" WHERE (staff_id = 13)
ActiveRecord::StatementInvalid (SQLite3::SQLException: no such column: staff_id: SELECT * FROM "services" WHERE (staff_id = 13) ):
Any idea why??
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我通常使用 has_many 然后通过，但概念是相同的。您需要在搜索中包含关联，因此
这将执行外部联接，因此将包含所有服务并立即加载员工数据。
这将执行内部联接并且仅具有服务数据集（如果您调用
service.staffs来获取未经请求的建议，则必须转到数据库，我建议稍微修改您的查询。
该数组会转义您的
staff_id变量有助于防止恶意代码攻击。I normally use has_many and then through, but the concept is the same. You need to include the association in the search so either
This will do an outer join so will include all services and will eager load the staff data.
This will do an inner join and only have the service datasets (it will have to go to the database if you call
service.staffsfor unsolicited advice, I recommend modifying your query a bit.
The array escapes your
staff_idvariable to help to prevent malicious code attacks.