我正在尝试在Slick 3.1.1中执行多个连接操作。我想要达到的结果是这样的:
SELECT * FROM customer LEFT JOIN customer_address ON customer.id = customer_address.customer_id LEFT JOIN address ON customer_address.address_id = address.id
我尝试过以下方法:
val query = for {
c <- Customer
ca <- CustomerAddress if ca.customerId === c.id
a <- Address if a.id === ca.addressId
} yield (c, a)
这里的问题在于如果客户没有地址,那么它不会出现,这是有道理的。
然后我尝试了这个:
val query2 = for {
(c, ca, a) <- (Customer joinLeft CustomerAddress on (_.id === _.customerId)) joinLeft Address on (_._2.addressId === _.id)
} yield (c, a)
这里的问题在于,当我使用
_._2
作为Rep
对象时,在_._2.addressId
上出现了错误。具体错误信息:
Error:(21, 110) value addressId is not a member of slick.lifted.Rep[Option[Models.Tables.CustomerAddress]]
(c, ca, a) <- (Customer joinLeft CustomerAddress on (_.id === _.customerId)) joinLeft Address on (_._2.addressId === _.id)
自动生成的Slick Tables类: http://pastebin.com/e4M3cGU8
我如何使用Slick获得我想要的结果?