Add assignment model

backend/examples/migrations/0008_assignment.py

@@ -0,0 +1,45 @@
+# Generated by Django 4.1.10 on 2023-07-24 05:39
+
+from django.conf import settings
+from django.db import migrations, models
+import django.db.models.deletion
+import uuid
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("projects", "0008_project_allow_member_to_create_label_type_and_more"),
+        migrations.swappable_dependency(settings.AUTH_USER_MODEL),
+        ("examples", "0007_example_score"),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name="Assignment",
+            fields=[
+                ("id", models.UUIDField(default=uuid.uuid4, editable=False, primary_key=True, serialize=False)),
+                ("created_at", models.DateTimeField(auto_now_add=True, db_index=True)),
+                ("updated_at", models.DateTimeField(auto_now=True)),
+                (
+                    "assignee",
+                    models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, to=settings.AUTH_USER_MODEL),
+                ),
+                (
+                    "example",
+                    models.ForeignKey(
+                        on_delete=django.db.models.deletion.CASCADE, related_name="assignments", to="examples.example"
+                    ),
+                ),
+                (
+                    "project",
+                    models.ForeignKey(
+                        on_delete=django.db.models.deletion.CASCADE, related_name="assignments", to="projects.project"
+                    ),
+                ),
+            ],
+            options={
+                "unique_together": {("example", "assignee")},
+            },
+        ),
+    ]

backend/examples/models.py

@@ -1,6 +1,7 @@
 import uuid
 
 from django.contrib.auth.models import User
+from django.core.exceptions import ValidationError
 from django.db import models
 from django_drf_filepond.models import DrfFilePondStoredStorage
 
@@ -37,6 +38,29 @@ class Example(models.Model):
         ordering = ["created_at"]
 
 
+class Assignment(models.Model):
+    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
+    project = models.ForeignKey(to=Project, on_delete=models.CASCADE, related_name="assignments")
+    example = models.ForeignKey(to=Example, on_delete=models.CASCADE, related_name="assignments")
+    assignee = models.ForeignKey(to=User, on_delete=models.CASCADE)
+    created_at = models.DateTimeField(auto_now_add=True, db_index=True)
+    updated_at = models.DateTimeField(auto_now=True)
+
+    class Meta:
+        unique_together = (("example", "assignee"),)
+
+    def clean(self):
+        # assignee must be a member of the project
+        if not self.project.members.filter(id=self.assignee.id).exists():
+            raise ValidationError("Assignee must be a member of the project")
+
+        # example must be in the project
+        if not self.project.examples.filter(id=self.example.id).exists():
+            raise ValidationError("Example must be in the project")
+
+        return super().clean()
+
+
 class ExampleState(models.Model):
     objects = ExampleStateManager()
     example = models.ForeignKey(to=Example, on_delete=models.CASCADE, related_name="states")