feat: Implement unique index for team-assessment in submissions

Author: GabrielCWT

lib/cadet/assessments/submission.ex

@@ -45,6 +45,7 @@ defmodule Cadet.Assessments.Submission do
     |> foreign_key_constraint(:student_id)
     |> foreign_key_constraint(:assessment_id)
     |> foreign_key_constraint(:unsubmitted_by_id)
+    |> unique_constraint(:unique_team_id, name: :submissions_team_id_assessment_id_unique_index)
   end
 
   defp validate_xor_relationship(changeset) do

priv/repo/migrations/20241014200600_create_teams_submission_constraint.exs

@@ -0,0 +1,17 @@
+defmodule Cadet.Repo.Migrations.CreateTeamsSubmissionConstraint do
+  use Ecto.Migration
+
+  def up do
+    create(
+      unique_index(
+        :submissions,
+        [:team_id, :assessment_id],
+        name: :submissions_team_id_assessment_id_unique_index
+      )
+    )
+  end
+
+  def down do
+    drop(constraint(:submissions, :submissions_team_id_assessment_id_unique_index))
+  end
+end