[planner/backend] Model and API implementation

apps/planner/models.py

@@ -3,11 +3,11 @@
 from enum import Enum, auto
 from typing import Dict, List, Tuple, Union, cast
 
+from django.core.validators import MinValueValidator, MaxValueValidator
 from django.db import models
 
 from apps.session.models import UserProfile
-
-from apps.subject.models import Department
+from apps.subject.models import Department, Course
 
 
 # change into - TODO
@@ -168,10 +168,23 @@ def credit_for_track(cls: Credit, user: UserProfile, track: Track) -> Dict[DeptC
 
 
 class Planner(models.Model):
-    user = models.ForeignKey(UserProfile, on_delete=models.CASCADE, db_index=True)
+    user = models.ForeignKey(UserProfile, 
+                             related_name="planners", on_delete=models.CASCADE, db_index=True)
+
     entrance_year = models.IntegerField(db_index=True)
-    # TODO add track
-    # TODO add to_json() function
+    track = models.ForeignKey(Track, on_delete=models.CASCADE, db_index=True)
+    arrange_order = models.SmallIntegerField(db_index=True)
+
+    def to_json(self, nested=False):
+        result = {
+            "id": self.id,
+            "arrange_order": self.arrange_order,
+        }
+        return result
+
+    @classmethod
+    def get_related_planners(cls, user, entrance_year, track):
+        return Planner.objects.filter(user=user, entrance_year=entrance_year, track=track)
 
 
 class PlannerItem(models.Model):

apps/planner/services.py

@@ -0,0 +1,22 @@
+from django.db.models import F, Case, When
+
+from .models import Planner
+
+
+def reorder_planner(planner: Planner, target_arrange_order: int):
+    related_planners = Planner.get_related_planners(planner.user,
+                                                    planner.entrance_year, planner.track)
+    original_arrange_order = planner.arrange_order
+
+    if target_arrange_order < original_arrange_order:
+        related_planners.filter(arrange_order__gte=target_arrange_order,
+                                arrange_order__lte=original_arrange_order) \
+                        .update(arrange_order=Case(When(arrange_order=original_arrange_order,
+                                                        then=target_arrange_order),
+                                                        default=F("arrange_order")+1))
+    elif target_arrange_order > original_arrange_order:
+        related_planners.filter(arrange_order__gte=original_arrange_order,
+                                arrange_order__lte=target_arrange_order) \
+                        .update(arrange_order=Case(When(arrange_order=original_arrange_order,
+                                                        then=target_arrange_order),
+                                                        default=F("arrange_order")-1))