Slick group by count - scala

Question

Let's say I have organizations, each organization has different groups, and users subscribe to groups.
case class OrganizationEntity(id: Option[Int], name: String)
case class GroupEntity(id: Option[Int], organizationId: Int, name: String)
case class GroupUserEntity(groupId: Int, userId: Int)
I need to get all groups of an organization, with the organizationName, and the quantity of users subscribed to that group.
In SQL, this can be easily done with this query:
SELECT g.*, o.organizationname, COUNT(DISTINCT gu.userid) FROM `group` g
LEFT JOIN organization o ON g.orgid = o.organizationid
LEFT JOIN group_user gu ON g.groupid = gu.groupid
WHERE g.orgid = 1234
GROUP BY g.groupid;
But I am struggling to replicate that in slick,
I've started writing this, but I am stuck now:
def findByOrganizationId(organizationId: Int) = {
(for {
g <- groups if g.organizationId === organizationId
o <- organizations if o.id === organizationId
gu <- groupUsers if g.id === gu.groupid
} yield (g, o.name, gu)).groupBy(_._3.groupid).map { case (_, values) => (values.map { case (g, orgname, users) => (g, orgname, users.) } }.result
}

Answer 1

You can just add .length to do the count in your code.
I think should also work directly in the yield so you don't need the groupBy:
def findByOrganizationId(organizationId: Int) = {
(for {
g <- groups if g.organizationId === organizationId
o <- organizations if o.id === organizationId
gu <- groupUsers if g.id === gu.groupid
} yield (g, o.name, gu.length)).result
}