Slick join with subqueries - scala

Question

I build following SQL Query
SELECT
v.uuid, d.start_time, d.end_time
FROM
visits v
INNER JOIN
visit_dates d ON v.uuid = d.visit_uuid
WHERE
v.study_environment_site_uuid = (SELECT
study_environment_site_uuid
FROM
visits
WHERE
uuid = 'e4663612-39f9-4c43-bd86-c4c5a9235b03')
AND v.uuid != 'e4663612-39f9-4c43-bd86-c4c5a9235b03'
AND d.start_time < (SELECT start_time FROM visit_dates WHERE visit_uuid = 'e4663612-39f9-4c43-bd86-c4c5a9235b03' ORDER BY start_time LIMIT 1)
ORDER BY d.start_time;
now trying to reflect that into Slick
(for {
vSes <- visits.filter(_.uuid === uuid)
vDate <- visitDates.filter(_.visitUuid === uuid).sortBy(_.startTime).take(1)
(v, d) <- visits join visitDates on (_.uuid === _.visitUuid)
if (v.uuid =!= uuid && v.studyEnvironmentSiteUuid === vSes.studyEnvironmentSiteUuid && d.startTime < vDate.startTime)
} yield (v.uuid)).result.map(_.headOption)
But this produced wrong result. I am using Slick 3.2.1
Following SQL is generated
SELECT
x2.`uuid`,
x7.start_time
FROM
`visits` x3,
(SELECT
`visit_uuid` AS x4, `start_time` AS x5
FROM
`visit_dates`
WHERE
`visit_uuid` = ?
ORDER BY `start_time`
LIMIT 1) x6,
`visits` x2,
`visit_dates` x7
WHERE
((x2.`uuid` = x7.`visit_uuid`)
AND ((NOT (x2.`uuid` = ?))
AND (x7.`start_time` < x6.x5)))
AND ((x3.`uuid` = ?)
AND (x2.`study_environment_site_uuid` = x3.`study_environment_site_uuid`));
Generated query is not a join and returns multiple rows instead of one that the manual query produces.
Any ideas/pointers?

Answer 1

As there isn't an answer yet, I will post my workaround for the problem
for {
(v, d) <- visits join visitDates on (_.uuid === _.visitUuid)
vSes <- visits.filter(_.uuid === uuid)
vDate <- visitDates.filter(_.visitUuid === uuid).sortBy(_.startTime).take(1)
if v.uuid =!= uuid && v.studyEnvironmentSiteUuid === vSes.studyEnvironmentSiteUuid && d.startTime < vDate.startTime
} yield (v.uuid, d.startTime)).result.map {
case results#(_ +: _) => Some(results.maxBy(_._2)._1)
case _ => None
}