Add ExampleState model

backend/api/migrations/0015_examplestate.py

@@ -0,0 +1,28 @@
+# Generated by Django 3.2.3 on 2021-06-07 01:48
+
+from django.conf import settings
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        migrations.swappable_dependency(settings.AUTH_USER_MODEL),
+        ('api', '0014_auto_20210603_0438'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='ExampleState',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('confirmed_at', models.DateTimeField(auto_now=True)),
+                ('confirmed_by', 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='states', to='api.example')),
+            ],
+            options={
+                'unique_together': {('example', 'confirmed_by')},
+            },
+        ),
+    ]

backend/api/models.py

@@ -149,6 +149,22 @@ class Example(models.Model):
         return Comment.objects.filter(example=self.id).count()
 
 
+class ExampleState(models.Model):
+    example = models.ForeignKey(
+        to=Example,
+        on_delete=models.CASCADE,
+        related_name='states'
+    )
+    confirmed_by = models.ForeignKey(
+        to=User,
+        on_delete=models.CASCADE
+    )
+    confirmed_at = models.DateTimeField(auto_now=True)
+
+    class Meta:
+        unique_together = (('example', 'confirmed_by'),)
+
+
 class Comment(models.Model):
     text = models.TextField()
     example = models.ForeignKey(