Question

如何在多个字段上进行连接，例如下面的示例？

val ownerId = 1
val contactType = 1
...
val contact = for {
  (t, c) <- ContactTypes leftJoin Contacts on (_.id === _.typeId && _.ownerId === ownerId)
  if t.id === contactType
} yield (c.?, t)

如何使用Slick 2.0.1实现这一目标？理所当然，我需要光滑来生成这种查询

SELECT
    x2."contact_id",
    x2."type_id",
    x2."owner_id",
    x2."value",
    x2."created_on",
    x2."updated_on",
    x3."id",
    x3."type",
    x3."model"
FROM
    (
        SELECT
            x4."id" AS "id",
            x4."type" AS "type",
            x4."model" AS "model"
        FROM
            "contact_types" x4
    )x3
LEFT OUTER JOIN(
    SELECT
        x5."created_on" AS "created_on",
        x5."value" AS "value",
        x5."contact_id" AS "contact_id",
        x5."updated_on" AS "updated_on",
        x5."type_id" AS "type_id",
        x5."owner_id" AS "owner_id"
    FROM
        "contacts" x5
)x2 ON x3."id" = x2."type_id" AND x2.owner_id = 1
WHERE
    (x3."id" = 3)

请注意 ON x3。“id”= x2。“type_id”AND x2.owner_id = 16

Answer 1

好的，所以在深入挖掘网站和源代码后，我想我终于找到了解决方案

leftJoin on（）方法接受以下参数 pred：（E1，E2）=＆gt; T ，所以我们可以这样做

val contacts = for {
  (t, c) <- ContactTypes leftJoin Contacts on ( (type, contact) => {
    type.id === contact.typeId && contact.ownerId === ownerId
  } )
} yield (c.?, t)

根据需要生成sql查询。

Scala Slick 2加入了多个领域？

1 个答案: