Add an optional submission cap and allow per-student overrides

tin/apps/assignments/admin.py

@@ -12,6 +12,7 @@
     MossResult,
     Quiz,
     QuizLogMessage,
+    SubmissionCap,
 )
 
 
@@ -140,3 +141,9 @@ def match(self, obj):
         elif obj.match_type == "C":
             return f"*{obj.match_value}*"
         return ""
+
+
+@admin.register(SubmissionCap)
+class SubmissionCapAdmin(admin.ModelAdmin):
+    list_display = ("assignment", "submission_cap", "student")
+    save_as = True

tin/apps/assignments/forms.py

@@ -7,14 +7,17 @@
 from django.conf import settings
 
 from ..submissions.models import Submission
-from .models import Assignment, Folder, MossResult
+from .models import Assignment, Folder, MossResult, SubmissionCap
 
 logger = getLogger(__name__)
 
 
 class AssignmentForm(forms.ModelForm):
     due = forms.DateTimeInput()
 
+    submission_cap = forms.IntegerField(min_value=1)
+    submission_cap_after_due = forms.IntegerField(min_value=1, required=False)
+
     def __init__(self, course, *args, **kwargs):
         super().__init__(*args, **kwargs)
         self.fields["folder"].queryset = Folder.objects.filter(course=course)
@@ -136,6 +139,8 @@ class Meta:
                     "submission_limit_count",
                     "submission_limit_interval",
                     "submission_limit_cooldown",
+                    "submission_cap",
+                    "submission_cap_after_due",
                 ),
                 "collapsed": True,
             },
@@ -150,6 +155,8 @@ class Meta:
             'internet access" below. If set, it increases the amount '
             "of time it takes to start up the grader (to about 1.5 "
             "seconds). This is not recommended unless necessary.",
+            "submission_cap": "The maximum number of submissions that can be made, or empty for unlimited.",
+            "submission_cap_after_due": "The maximum number of submissions that can be made after the due date, or empty for unlimited.",
             "submission_limit_count": "",
             "submission_limit_interval": "Tin sets rate limits on submissions. If a student tries "
             "to submit too many submissions in a given interval, "
@@ -178,7 +185,22 @@ class Meta:
         }
 
     def __str__(self) -> str:
-        return f"AssignmentForm(\"{self['name'].value()}\")"
+        return f'AssignmentForm("{self["name"].value()}")'
+
+    def save(self) -> Assignment:
+        assignment = super().save()
+        sub_cap = self.cleaned_data.get("submission_cap")
+        sub_cap_after_due = self.cleaned_data.get("submission_cap_after_due")
+        if sub_cap is not None or sub_cap_after_due is not None:
+            SubmissionCap.objects.update_or_create(
+                assignment=assignment,
+                student=None,
+                defaults={
+                    "submission_cap": sub_cap,
+                    "submission_cap_after_due": sub_cap_after_due,
+                },
+            )
+        return assignment
 
 
 class GraderScriptUploadForm(forms.Form):
@@ -241,3 +263,24 @@ class Meta:
             "name",
         ]
         help_texts = {"name": "Note: Folders are ordered alphabetically."}
+
+
+class SubmissionCapForm(forms.ModelForm):
+    def __init__(self, **kwargs) -> None:
+        super().__init__(**kwargs)
+
+        nonrequired = ("submission_cap", "submission_cap_after_due")
+        for f in nonrequired:
+            self.fields[f].required = False
+
+    class Meta:
+        model = SubmissionCap
+        fields = ["submission_cap", "submission_cap_after_due"]
+        help_texts = {
+            "submission_cap_after_due": (
+                "The submission cap after the due date (or empty for unlimited). "
+                "By default, this is the same as the submission cap."
+            ),
+            "student": "The student to apply the cap to.",
+        }
+        labels = {"submission_cap_after_due": "Submission cap after due date"}

tin/apps/assignments/migrations/0033_submissioncap_submissioncap_unique_type_and_more.py

@@ -0,0 +1,35 @@
+# Generated by Django 4.2.16 on 2025-01-10 01:57
+
+from django.conf import settings
+import django.core.validators
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        migrations.swappable_dependency(settings.AUTH_USER_MODEL),
+        ('assignments', '0032_assignment_quiz_description_and_more'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='SubmissionCap',
+            fields=[
+                ('id', models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('submission_cap', models.PositiveSmallIntegerField(null=True, validators=[django.core.validators.MinValueValidator(1)])),
+                ('submission_cap_after_due', models.PositiveSmallIntegerField(null=True)),
+                ('assignment', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='submission_caps', to='assignments.assignment')),
+                ('student', models.ForeignKey(null=True, on_delete=django.db.models.deletion.CASCADE, to=settings.AUTH_USER_MODEL)),
+            ],
+        ),
+        migrations.AddConstraint(
+            model_name='submissioncap',
+            constraint=models.UniqueConstraint(fields=('student', 'assignment'), name='unique_type'),
+        ),
+        migrations.AddConstraint(
+            model_name='submissioncap',
+            constraint=models.CheckConstraint(check=models.Q(('submission_cap__isnull', False), ('submission_cap_after_due__isnull', False), _connector='OR'), name='has_submission_cap', violation_error_message='Either the submission cap before or after the due date has to be set'),
+        ),
+    ]

tin/apps/assignments/models.py

@@ -159,6 +159,7 @@ class Assignment(models.Model):
 
     has_network_access = models.BooleanField(default=False)
 
+    # WARNING: this is the rate limit
     submission_limit_count = models.PositiveIntegerField(
         default=90,
         validators=[MinValueValidator(10)],
@@ -183,6 +184,8 @@ class Assignment(models.Model):
 
     objects = AssignmentQuerySet.as_manager()
 
+    submission_caps: models.QuerySet[SubmissionCap]
+
     def __str__(self):
         return self.name
 
@@ -192,6 +195,59 @@ def get_absolute_url(self):
     def __repr__(self):
         return self.name
 
+    def within_submission_limit(self, student) -> bool:
+        """Check if a student is within the submission limit for an assignment."""
+        # teachers should have infinite submissions
+        if not student.is_student or self.is_quiz or not self.submission_caps.exists():
+            return True
+
+        # note that this doesn't care about killed/incomplete submissions
+        submission_count = self.submissions.filter(student=student).count()
+
+        cap = self.find_submission_cap(student)
+        return submission_count < cap
+
+    def find_submission_cap(self, student) -> float:
+        """Given a student, find the submission cap.
+
+        This takes into account student overrides, and due dates.
+        """
+        if student.is_superuser or student.is_teacher:
+            return float("inf")
+        cap = self.find_student_override(student)
+        if cap is not None:
+            return cap.calculate_submission_cap()
+        elif timezone.localtime() > self.due:
+            return self.submission_cap_after_due()
+        return self.before_submission_cap()
+
+    def find_student_override(self, student) -> SubmissionCap | None:
+        """Find an :class:`.SubmissionCap` for a student.
+
+        Returns ``None`` if no override exists.
+        """
+        return self.submission_caps.filter(student=student).first()
+
+    def before_submission_cap(self) -> float:
+        """Get the submission cap for an assignment before the due date.
+
+        Returns ``float("inf")`` if no cap is found.
+        """
+        cap = self.submission_caps.filter(student__isnull=True).first()
+        if cap is not None and cap.submission_cap is not None:
+            return cap.submission_cap
+        return float("inf")
+
+    def submission_cap_after_due(self) -> float:
+        """Get the submission cap after the due date.
+
+        Returns ``float("inf")`` if no cap is found.
+        """
+        cap = self.submission_caps.filter(student__isnull=True).first()
+        if cap is not None and cap.submission_cap_after_due is not None:
+            return cap.submission_cap_after_due
+        return float("inf")
+
     def make_assignment_dir(self) -> None:
         """Creates the directory where the assignment grader scripts go."""
         assignment_path = os.path.join(settings.MEDIA_ROOT, f"assignment-{self.id}")
@@ -371,6 +427,48 @@ def quiz_issues_for_student(self, student) -> bool:
         )
 
 
+class SubmissionCap(models.Model):
+    """Submission cap information"""
+
+    student = models.ForeignKey(
+        settings.AUTH_USER_MODEL,
+        on_delete=models.CASCADE,
+        null=True,
+    )
+
+    assignment = models.ForeignKey(
+        Assignment,
+        on_delete=models.CASCADE,
+        related_name="submission_caps",
+    )
+
+    submission_cap = models.PositiveSmallIntegerField(null=True, validators=[MinValueValidator(1)])
+    submission_cap_after_due = models.PositiveSmallIntegerField(null=True)
+
+    class Meta:
+        constraints = [
+            # TODO: In django 5.0+ add nulls_distinct=False
+            models.UniqueConstraint(fields=["student", "assignment"], name="unique_type"),
+            models.CheckConstraint(
+                check=Q(submission_cap__isnull=False) | Q(submission_cap_after_due__isnull=False),
+                violation_error_message="Either the submission cap before or after the due date has to be set",
+                name="has_submission_cap",
+            ),
+        ]
+
+    def __str__(self) -> str:
+        return f"{type(self).__name__}(submission_cap={self.submission_cap})"
+
+    def calculate_submission_cap(self) -> float:
+        """Get the submission cap for a given due date"""
+        if timezone.localtime() > self.assignment.due and self.submission_cap_after_due is not None:
+            return self.submission_cap_after_due
+        # This is the case where only submission_cap_after_due is set
+        if self.submission_cap is not None:
+            return self.submission_cap
+        return float("inf")
+
+
 class CooldownPeriod(models.Model):
     assignment = models.ForeignKey(
         Assignment,

tin/apps/assignments/tests/test_assignments.py

@@ -24,6 +24,8 @@ def test_create_assignment(client, course) -> None:
         "submission_limit_cooldown": "30",
         "is_quiz": False,
         "quiz_action": "2",
+        "submission_cap": "100",
+        "submission_cap_after_due": "100",
     }
     response = client.post(
         reverse("assignments:add", args=[course.id]),