Add better exception handling for unknown Dailies

backend-services/feed-service/app/controllers/DailyController.scala

@@ -5,7 +5,7 @@ import play.api.mvc._
 import play.api.libs.json.JsValue
 
 import models.{Daily}
-import models.exceptions.ConflictException
+import models.exceptions.{ConflictException, NotFoundException}
 
 import scala.concurrent.TimeoutException
 import org.bson.types.ObjectId
@@ -94,6 +94,7 @@ class DailyController @Inject()(val controllerComponents: ControllerComponents)
     } catch {
         case _: TimeoutException => BadRequest("Request timed out")
         case ex: ConflictException => BadRequest(ex.getMessage())
+        case ex: NotFoundException => BadRequest(ex.getMessage())
         case _: Throwable => BadRequest("Exception raised")
     }
   }

backend-services/feed-service/app/models/Daily.scala

 package models
 
 import repositories.{DailyRepository}
-import models.exceptions.{ConflictException}
+import models.exceptions.{ConflictException, NotFoundException}
 
 import scala.concurrent.ExecutionContext.Implicits.global
 import scala.concurrent.{Future, Await}
@@ -66,8 +66,11 @@ object Daily {
 
     def likeAsync(dailyId: ObjectId, likerId: ObjectId, timeout: Int = 4): Unit = {
         val result: Future[Unit] = for {
-            daily: Daily  <- dailyRepo.getById(dailyId)
+            oDaily: Option[Daily]  <- dailyRepo.getById(dailyId)
             like: Unit <- {
+                // Check daily with given ID exists
+                val daily = if (oDaily.isEmpty) throw new NotFoundException("No daily with given ID.") else oDaily.get
+                
                 // Check user has not already liked Daily
                 if (daily.usersLiked.contains(likerId)) throw new ConflictException("User has already liked this Daily.")
 

backend-services/feed-service/app/models/exceptions/NotFoundException.scala

+package models.exceptions
+
+case class NotFoundException(message: String) extends Exception(message)

backend-services/feed-service/app/repositories/Repository.scala

@@ -55,11 +55,11 @@ class Repository[T: ClassTag](databaseName: String, collectionName: String) {
     /**
      * Gets a record with the given ID in the collection.
      * 
-     * @return A Future containing a sequence of matching documents.
+     * @return A Future containing an optional matching document.
      */
-    def getById(id: ObjectId): Future[T] = {
+    def getById(id: ObjectId): Future[Option[T]] = {
         val filter: Bson = Filters.equal[ObjectId]("_id", id)
-        MongoConnection.find[T](collection, filter).map(_.head)
+        MongoConnection.find[T](collection, filter).map(_.headOption)
     }
 
     /**