feat(lastVisitedUniversities) : add LastVisitedUniversity model and migration of the new model

Relates to #149

backend/backend_app/admin.py

@@ -14,6 +14,7 @@ from backend_app.models.exchange import Exchange, UnivMajorMinors
 from backend_app.models.exchangeFeedback import ExchangeFeedback
 from backend_app.models.for_testing.moderation import ForTestingModeration
 from backend_app.models.for_testing.versioning import ForTestingVersioning
+from backend_app.models.lastVisitedUniversities import LastVisitedUniversity
 from backend_app.models.offer import Offer
 from backend_app.models.partner import Partner
 from backend_app.models.pendingModeration import PendingModeration
@@ -38,6 +39,7 @@ ALL_MODELS = [
     Course,
     CourseFeedback,
     Currency,
+    LastVisitedUniversity,
     Offer,
     PendingModeration,
     Exchange,

backend/backend_app/migrations/0005_lastvisiteduniversity.py

+# Generated by Django 2.1.7 on 2020-05-24 08:53
+
+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),
+        ("backend_app", "0004_merge_20200503_1749"),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name="LastVisitedUniversity",
+            fields=[
+                (
+                    "id",
+                    models.AutoField(
+                        auto_created=True,
+                        primary_key=True,
+                        serialize=False,
+                        verbose_name="ID",
+                    ),
+                ),
+                ("ts", models.DateTimeField(auto_now=True)),
+                (
+                    "university",
+                    models.ForeignKey(
+                        null=True,
+                        on_delete=django.db.models.deletion.CASCADE,
+                        to="backend_app.University",
+                    ),
+                ),
+                (
+                    "user",
+                    models.ForeignKey(
+                        null=True,
+                        on_delete=django.db.models.deletion.CASCADE,
+                        to=settings.AUTH_USER_MODEL,
+                    ),
+                ),
+            ],
+            options={"abstract": False},
+        )
+    ]

backend/backend_app/models/lastVisitedUniversities.py

+from django.db import models
+
+from backend_app.models.abstract.base import BaseModel
+
+from backend_app.permissions.moderation import ModerationLevels
+
+from base_app.models import User
+from backend_app.models.university import University
+
+
+class LastVisitedUniversity(BaseModel):
+    moderation_level = ModerationLevels.NO_MODERATION
+
+    user = models.ForeignKey(User, on_delete=models.CASCADE, null=True)
+    university = models.ForeignKey(University, on_delete=models.CASCADE, null=True)
+    ts = models.DateTimeField(auto_now=True)