link to student manager class - closes #9650

app/controllers/Clas.scala

@@ -437,9 +437,10 @@ final class Clas(env: Env, authC: Auth) extends LilaController(env) {
     Secure(_.Teacher) { implicit ctx => me =>
       WithClassAndStudents(me, id) { (clas, students) =>
         WithStudent(clas, username) { s =>
-          env.activity.read.recent(s.user, 14) map { activity =>
-            views.html.clas.student.show(clas, students, s, activity)
-          }
+          for {
+            withManagingClas <- env.clas.api.student.withManagingClas(s, clas)
+            activity         <- env.activity.read.recent(s.user, 14)
+          } yield views.html.clas.student.show(clas, students, withManagingClas, activity)
         }
       }
     }

app/views/clas/student.scala

@@ -15,12 +15,12 @@ object student {
   def show(
       clas: Clas,
       students: List[Student],
-      s: Student.WithUser,
+      s: Student.WithUserAndManagingClas,
       activities: Vector[lila.activity.ActivityView]
   )(implicit ctx: Context) =
     bits.layout(s.user.username, Left(clas withStudents students), s.student.some)(
       cls := "student-show",
-      top(clas, s),
+      top(clas, s.withUser),
       div(cls := "box__pad")(
         standardFlash(),
         ctx.flash("password").map { password =>
@@ -56,7 +56,15 @@ object student {
               title := trans.clas.upgradeFromManaged.txt()
             )(trans.clas.release())
           )
-        ),
+        ) orElse s.managingClas.map { managingClas =>
+          div(cls := "student-show__managed")(
+            p(trans.clas.thisStudentAccountIsManaged()),
+            a(href := routes.Clas.studentShow(managingClas.id.value, s.user.username))(
+              "Class: ",
+              managingClas.name
+            )
+          )
+        },
         views.html.activity(s.user, activities)
       )
     )

modules/clas/src/main/ClasApi.scala

@@ -142,13 +142,11 @@ final class ClasApi(
           import framework._
           Match($doc("clasId" -> clas.id) ++ selector) -> List(
             PipelineOperator(
-              $doc(
-                "$lookup" -> $doc(
-                  "from"         -> userRepo.coll.name,
-                  "as"           -> "user",
-                  "localField"   -> "userId",
-                  "foreignField" -> "_id"
-                )
+              $lookup.simple(
+                from = userRepo.coll,
+                as = "user",
+                local = "userId",
+                foreign = "_id"
               )
             ),
             UnwindField("user")
@@ -199,6 +197,29 @@ final class ClasApi(
     def get(clas: Clas, user: User): Fu[Option[Student.WithUser]] =
       get(clas, user.id) map2 { Student.WithUser(_, user) }
 
+    def withManagingClas(s: Student.WithUser, clas: Clas): Fu[Student.WithUserAndManagingClas] = {
+      if (s.student.managed) fuccess(clas.some)
+      else
+        colls.student
+          .aggregateOne(ReadPreference.secondaryPreferred) { framework =>
+            import framework._
+            Match($doc("userId" -> s.user.id, "managed" -> true)) -> List(
+              PipelineOperator(
+                $lookup.simple(
+                  from = colls.clas,
+                  as = "clas",
+                  local = "clasId",
+                  foreign = "_id"
+                )
+              ),
+              UnwindField("clas")
+            )
+          }
+          .map {
+            _.flatMap(_.getAsOpt[Clas]("clas"))
+          }
+    } map { Student.WithUserAndManagingClas(s, _) }
+
     def update(from: Student, data: ClasForm.StudentData): Fu[Student] = {
       val student = data update from
       coll.update.one($id(student.id), student) inject student

modules/clas/src/main/Student.scala

@@ -46,6 +46,11 @@ object Student {
 
   case class WithUser(student: Student, user: User)
 
+  case class WithUserAndManagingClas(withUser: WithUser, managingClas: Option[Clas]) {
+    def student = withUser.student
+    def user    = withUser.user
+  }
+
   case class WithPassword(student: Student, password: User.ClearPassword)
 
   case class ManagedInfo(createdBy: User, clas: Clas)