fix: Fix empty submisisons creation for team assessments (#1202)

* feat: Implement unique index for team-assessment in submissions

* fix: Fix creation of empty submission for teams

* chore: Negate the if statement

* chore: Format

* Let Elixir do its magic

* fix: Duplicate team submissions being created

---------

Co-authored-by: Richard Dominick <[email protected]>

lib/cadet/assessments/submission.ex

@@ -43,6 +43,7 @@ defmodule Cadet.Assessments.Submission do
     |> validate_xor_relationship
     |> validate_required(@required_fields)
     |> foreign_key_constraint(:student_id)
+    |> foreign_key_constraint(:team_id)
     |> foreign_key_constraint(:assessment_id)
     |> foreign_key_constraint(:unsubmitted_by_id)
   end

lib/cadet/jobs/autograder/grading_job.ex

@@ -112,36 +112,54 @@ defmodule Cadet.Autograder.GradingJob do
         |> where([_, tm], tm.student_id == ^student_id)
         |> Repo.one()
 
-      if !team do
-        # Student is not in any team
-        # Create new team just for the student
-        team =
-          %Team{}
-          |> Team.changeset(%{
-            assessment_id: assessment.id
+      team =
+        if team do
+          team
+        else
+          # Student is not in any team
+          # Create new team just for the student
+          team =
+            %Team{}
+            |> Team.changeset(%{
+              assessment_id: assessment.id
+            })
+            |> Repo.insert!()
+
+          %TeamMember{}
+          |> TeamMember.changeset(%{
+            team_id: team.id,
+            student_id: student_id
           })
           |> Repo.insert!()
 
-        %TeamMember{}
-        |> TeamMember.changeset(%{
-          team_id: team.id,
-          student_id: student_id
-        })
-        |> Repo.insert!()
-      end
+          team
+        end
 
+      find_or_create_team_submission(team.id, assessment)
+    else
+      # Individual assessment
       %Submission{}
       |> Submission.changeset(%{
-        team_id: team.id,
+        student_id: student_id,
         assessment: assessment,
         status: :submitted
       })
       |> Repo.insert!()
+    end
+  end
+
+  defp find_or_create_team_submission(team_id, assessment) when is_ecto_id(team_id) do
+    submission =
+      Submission
+      |> where(team_id: ^team_id, assessment_id: ^assessment.id)
+      |> Repo.one()
+
+    if submission do
+      submission
     else
-      # Individual assessment
       %Submission{}
       |> Submission.changeset(%{
-        student_id: student_id,
+        team_id: team_id,
         assessment: assessment,
         status: :submitted
       })

priv/repo/migrations/20241014200600_create_teams_submission_constraint.exs

@@ -0,0 +1,8 @@
+defmodule Cadet.Repo.Migrations.CreateTeamsSubmissionConstraint do
+  use Ecto.Migration
+
+  def change do
+    create(index(:submissions, :team_id))
+    create(unique_index(:submissions, [:assessment_id, :team_id]))
+  end
+end