Add plan variety change tracking

backend/apps/plans/migrations/0010_planvarietychange.py

@@ -0,0 +1,32 @@
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('fields', '0006_e1c_chusankan_17_fields'),
+        ('plans', '0009_alter_ricetransplantentry_installed_seedling_boxes'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='PlanVarietyChange',
+            fields=[
+                ('id', models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('year', models.IntegerField(verbose_name='作付年度')),
+                ('changed_at', models.DateTimeField(auto_now_add=True, verbose_name='変更日時')),
+                ('reason', models.TextField(blank=True, default='', verbose_name='変更理由')),
+                ('moved_entry_count', models.IntegerField(default=0, verbose_name='移動エントリ数')),
+                ('field', models.ForeignKey(on_delete=django.db.models.deletion.PROTECT, related_name='plan_variety_changes', to='fields.field', verbose_name='圃場')),
+                ('new_variety', models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.SET_NULL, related_name='new_plan_variety_changes', to='plans.variety', verbose_name='変更後品種')),
+                ('old_variety', models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.SET_NULL, related_name='old_plan_variety_changes', to='plans.variety', verbose_name='変更前品種')),
+                ('plan', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='variety_changes', to='plans.plan', verbose_name='作付け計画')),
+            ],
+            options={
+                'verbose_name': '作付け計画品種変更履歴',
+                'verbose_name_plural': '作付け計画品種変更履歴',
+                'ordering': ['-changed_at', '-id'],
+            },
+        ),
+    ]

backend/apps/plans/models.py

@@ -65,6 +65,51 @@ class Plan(models.Model):
         return f"{self.field.name} - {self.year} - {self.crop.name}"
 
 
+class PlanVarietyChange(models.Model):
+    field = models.ForeignKey(
+        Field,
+        on_delete=models.PROTECT,
+        related_name='plan_variety_changes',
+        verbose_name='圃場',
+    )
+    year = models.IntegerField(verbose_name='作付年度')
+    plan = models.ForeignKey(
+        Plan,
+        on_delete=models.CASCADE,
+        related_name='variety_changes',
+        verbose_name='作付け計画',
+    )
+    changed_at = models.DateTimeField(auto_now_add=True, verbose_name='変更日時')
+    old_variety = models.ForeignKey(
+        Variety,
+        on_delete=models.SET_NULL,
+        related_name='old_plan_variety_changes',
+        verbose_name='変更前品種',
+        null=True,
+        blank=True,
+    )
+    new_variety = models.ForeignKey(
+        Variety,
+        on_delete=models.SET_NULL,
+        related_name='new_plan_variety_changes',
+        verbose_name='変更後品種',
+        null=True,
+        blank=True,
+    )
+    reason = models.TextField(blank=True, default='', verbose_name='変更理由')
+    moved_entry_count = models.IntegerField(default=0, verbose_name='移動エントリ数')
+
+    class Meta:
+        verbose_name = '作付け計画品種変更履歴'
+        verbose_name_plural = '作付け計画品種変更履歴'
+        ordering = ['-changed_at', '-id']
+
+    def __str__(self):
+        old_name = self.old_variety.name if self.old_variety else '未設定'
+        new_name = self.new_variety.name if self.new_variety else '未設定'
+        return f'{self.field.name} {self.year}: {old_name} -> {new_name}'
+
+
 class RiceTransplantPlan(models.Model):
     name = models.CharField(max_length=200, verbose_name='計画名')
     year = models.IntegerField(verbose_name='年度')

backend/apps/plans/serializers.py

@@ -5,6 +5,7 @@ from apps.fields.models import Field
 from apps.materials.models import StockTransaction
 from .models import Crop, Variety, Plan
 from .models import RiceTransplantEntry, RiceTransplantPlan
+from .services import NO_CHANGE, update_plan_with_variety_tracking
 
 
 class VarietySerializer(serializers.ModelSerializer):
@@ -44,10 +45,12 @@ class PlanSerializer(serializers.ModelSerializer):
         return Plan.objects.create(**validated_data)
 
     def update(self, instance, validated_data):
-        for attr, value in validated_data.items():
-            setattr(instance, attr, value)
-        instance.save()
-        return instance
+        return update_plan_with_variety_tracking(
+            instance,
+            crop=validated_data.get('crop', NO_CHANGE),
+            variety=validated_data.get('variety', NO_CHANGE),
+            notes=validated_data.get('notes', NO_CHANGE),
+        )
 
 
 class RiceTransplantEntrySerializer(serializers.ModelSerializer):

backend/apps/plans/services.py

@@ -0,0 +1,67 @@
+from django.db import transaction
+
+from .models import Plan, PlanVarietyChange
+
+
+class _NoChange:
+    pass
+
+
+NO_CHANGE = _NoChange()
+
+
+@transaction.atomic
+def update_plan_with_variety_tracking(
+    plan: Plan,
+    *,
+    crop=NO_CHANGE,
+    variety=NO_CHANGE,
+    notes=NO_CHANGE,
+    reason: str = '',
+):
+    old_variety = plan.variety
+    updated_fields = []
+
+    if crop is not NO_CHANGE:
+        plan.crop = crop
+        updated_fields.append('crop')
+    if variety is not NO_CHANGE:
+        plan.variety = variety
+        updated_fields.append('variety')
+    if notes is not NO_CHANGE:
+        plan.notes = notes
+        updated_fields.append('notes')
+
+    if updated_fields:
+        plan.save(update_fields=updated_fields)
+
+    if variety is not NO_CHANGE and _get_variety_id(old_variety) != _get_variety_id(plan.variety):
+        handle_plan_variety_change(plan, old_variety=old_variety, new_variety=plan.variety, reason=reason)
+
+    return plan
+
+
+@transaction.atomic
+def handle_plan_variety_change(plan: Plan, *, old_variety, new_variety, reason: str = ''):
+    if _get_variety_id(old_variety) == _get_variety_id(new_variety):
+        return None
+
+    change = PlanVarietyChange.objects.create(
+        field=plan.field,
+        year=plan.year,
+        plan=plan,
+        old_variety=old_variety,
+        new_variety=new_variety,
+        reason=reason,
+    )
+    process_plan_variety_change(change)
+    return change
+
+
+def process_plan_variety_change(change: PlanVarietyChange):
+    """後続 issue で施肥計画・田植え計画への移動処理を追加する入口。"""
+    return change
+
+
+def _get_variety_id(variety):
+    return getattr(variety, 'id', None)

backend/apps/plans/tests.py

@@ -1,3 +1,92 @@
+from django.contrib.auth import get_user_model
 from django.test import TestCase
+from rest_framework.test import APIRequestFactory, force_authenticate
 
-# Create your tests here.
+from apps.fields.models import Field
+from .models import Crop, Plan, PlanVarietyChange, Variety
+from .serializers import PlanSerializer
+from .views import PlanViewSet
+
+
+class PlanVarietyChangeTests(TestCase):
+    def setUp(self):
+        self.factory = APIRequestFactory()
+        self.user = get_user_model().objects.create_user(
+            username='tester',
+            password='secret12345',
+        )
+        self.crop = Crop.objects.create(name='水稲')
+        self.old_variety = Variety.objects.create(crop=self.crop, name='にこまる')
+        self.new_variety = Variety.objects.create(crop=self.crop, name='たちはるか特栽')
+        self.field = Field.objects.create(
+            name='足川北上',
+            address='高知県高岡郡',
+            area_tan='1.2000',
+            area_m2=1200,
+            owner_name='吉田',
+            group_name='北',
+            display_order=1,
+        )
+        self.plan = Plan.objects.create(
+            field=self.field,
+            year=2026,
+            crop=self.crop,
+            variety=self.old_variety,
+            notes='',
+        )
+
+    def test_serializer_update_creates_history_when_variety_changes(self):
+        serializer = PlanSerializer(
+            instance=self.plan,
+            data={'variety': self.new_variety.id},
+            partial=True,
+        )
+        self.assertTrue(serializer.is_valid(), serializer.errors)
+        serializer.save()
+
+        self.plan.refresh_from_db()
+        self.assertEqual(self.plan.variety_id, self.new_variety.id)
+
+        change = PlanVarietyChange.objects.get(plan=self.plan)
+        self.assertEqual(change.field_id, self.field.id)
+        self.assertEqual(change.year, 2026)
+        self.assertEqual(change.old_variety_id, self.old_variety.id)
+        self.assertEqual(change.new_variety_id, self.new_variety.id)
+        self.assertEqual(change.moved_entry_count, 0)
+
+    def test_serializer_update_does_not_create_history_without_variety_change(self):
+        serializer = PlanSerializer(
+            instance=self.plan,
+            data={'notes': 'メモ更新'},
+            partial=True,
+        )
+        self.assertTrue(serializer.is_valid(), serializer.errors)
+        serializer.save()
+
+        self.plan.refresh_from_db()
+        self.assertEqual(self.plan.notes, 'メモ更新')
+        self.assertFalse(PlanVarietyChange.objects.exists())
+
+    def test_bulk_update_creates_history_for_existing_plan(self):
+        view = PlanViewSet.as_view({'post': 'bulk_update'})
+        request = self.factory.post(
+            '/api/plans/bulk_update/',
+            {
+                'field_ids': [self.field.id],
+                'year': 2026,
+                'crop': self.crop.id,
+                'variety': self.new_variety.id,
+            },
+            format='json',
+        )
+        force_authenticate(request, user=self.user)
+
+        response = view(request)
+
+        self.assertEqual(response.status_code, 200)
+        self.plan.refresh_from_db()
+        self.assertEqual(self.plan.variety_id, self.new_variety.id)
+
+        change = PlanVarietyChange.objects.get(plan=self.plan)
+        self.assertEqual(change.old_variety_id, self.old_variety.id)
+        self.assertEqual(change.new_variety_id, self.new_variety.id)

backend/apps/plans/views.py

@@ -10,6 +10,7 @@ from .serializers import (
     RiceTransplantPlanSerializer,
     RiceTransplantPlanWriteSerializer,
 )
+from .services import update_plan_with_variety_tracking
 from apps.fields.models import Field
 
 
@@ -120,15 +121,23 @@ class PlanViewSet(viewsets.ModelViewSet):
         updated = 0
         created = 0
         for field_id in field_ids:
-            plan, was_created = Plan.objects.update_or_create(
-                field_id=field_id,
-                year=year,
-                defaults={'crop': crop, 'variety': variety}
-            )
-            if was_created:
+            plan = Plan.objects.filter(field_id=field_id, year=year).first()
+            if plan is None:
+                Plan.objects.create(
+                    field_id=field_id,
+                    year=year,
+                    crop=crop,
+                    variety=variety,
+                )
                 created += 1
-            else:
-                updated += 1
+                continue
+
+            update_plan_with_variety_tracking(
+                plan,
+                crop=crop,
+                variety=variety,
+            )
+            updated += 1
 
         return Response({'created': created, 'updated': updated, 'total': created + updated})