setupm transactions

gds/settings.py

@@ -29,6 +29,7 @@
     'django.contrib.staticfiles',
     #apps
     'stock',
+    'transactions',
 
     #3rd part apps
     'allauth',

gds/urls.py

@@ -7,4 +7,5 @@
     path('__debug__/', include("debug_toolbar.urls")),
     path('accounts/', include('allauth.urls')),
     path('stock/', include('stock.urls')),
+    path('transactions/', include('transactions.urls')),
 ]

stock/migrations/0002_gas_minimum_threshold.py

@@ -0,0 +1,18 @@
+# Generated by Django 5.0 on 2023-12-28 22:12
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('stock', '0001_initial'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='gas',
+            name='minimum_threshold',
+            field=models.PositiveIntegerField(default=50),
+        ),
+    ]

stock/models.py

@@ -6,6 +6,7 @@ class Gas(models.Model):
     quantity = models.PositiveIntegerField()
     price = models.DecimalField(max_digits=8, decimal_places=2)
     supplier = models.CharField(max_length=100, null=True, blank=True)
+    minimum_threshold = models.PositiveIntegerField(default= 50)
     created = models.DateTimeField(auto_now_add=True)
     updated = models.DateTimeField(auto_now=True)
 

stock/signals.py

@@ -0,0 +1,13 @@
+from django.db.models.signals import post_save
+from django.dispatch import receiver
+from django.core.mail import send_mail
+from .models import Gas
+
+@receiver(post_save, sender=Gas)
+def send_stock_alert(sender, instance, **kwargs):
+    if instance.quantity < instance.minimum_threshold:
+        subject = f"Gas stock alert: {instance.name}"
+        message = f"The stock of {instance.name} is below {instance.minimum_threshold} units."
+        from_email = "[email protected]"
+        recipient_list = ["[email protected]"]
+        send_mail(subject, message, from_email, recipient_list)

transactions/admin.py

@@ -0,0 +1,13 @@
+from django.contrib import admin
+from .models import Transaction
+
+@admin.register(Transaction)
+class TransactionAdmin(admin.ModelAdmin):
+    list_display = ('customer', 'quantity', 'product', 'created', 'updated', 'get_total_cost')
+    list_filter = ('product', 'created', 'updated')
+    search_fields = ('customer', 'product__name')
+    readonly_fields = ('total_cost',)
+
+    def get_total_cost(self, obj):
+        return obj.total_cost()
+    get_total_cost.short_description = 'Total Cost'

transactions/apps.py

@@ -0,0 +1,9 @@
+from django.apps import AppConfig
+
+
+class TransactionsConfig(AppConfig):
+    default_auto_field = 'django.db.models.BigAutoField'
+    name = 'transactions'
+
+    def ready(self):
+        import transactions.signals 

transactions/migrations/0001_initial.py

@@ -0,0 +1,28 @@
+# Generated by Django 5.0 on 2023-12-28 21:51
+
+import django.db.models.deletion
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    initial = True
+
+    dependencies = [
+        ('stock', '0001_initial'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='Transaction',
+            fields=[
+                ('id', models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('customer', models.CharField(max_length=100)),
+                ('quantity', models.DecimalField(decimal_places=2, max_digits=10)),
+                ('unit_cost', models.DecimalField(decimal_places=2, max_digits=10)),
+                ('created', models.DateTimeField(auto_now_add=True)),
+                ('updated', models.DateTimeField(auto_now=True)),
+                ('product', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='transaction', to='stock.gas')),
+            ],
+        ),
+    ]

transactions/migrations/0002_remove_transaction_unit_cost.py

@@ -0,0 +1,17 @@
+# Generated by Django 5.0 on 2023-12-28 22:20
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('transactions', '0001_initial'),
+    ]
+
+    operations = [
+        migrations.RemoveField(
+            model_name='transaction',
+            name='unit_cost',
+        ),
+    ]

transactions/models.py

@@ -0,0 +1,17 @@
+from django.db import models
+
+class Transaction(models.Model):
+    customer = models.CharField(max_length=100)
+    quantity = models.DecimalField(max_digits=10, decimal_places=2)
+    product = models.ForeignKey('stock.Gas', on_delete=models.CASCADE, related_name='transaction' )
+    created = models.DateTimeField(auto_now_add=True)
+    updated = models.DateTimeField(auto_now=True)
+
+    def __str__(self):
+        return f"{self.quantity} - {self.product.price}"
+
+    def total_cost(self):
+        try:
+            return self.quantity * self.product.price
+        except Exception as e:
+            return 0.00

transactions/signals.py

@@ -0,0 +1,14 @@
+from django.db.models.signals import post_save
+from django.dispatch import receiver
+from .models import Transaction
+
+@receiver(post_save, sender=Transaction)
+def reduce_stock_quantity(sender, instance, created, **kwargs):
+    if created:  # New transaction
+        instance.product.quantity -= instance.quantity
+        instance.product.save()
+    else:  # Existing transaction
+        original_transaction = Transaction.objects.get(pk=instance.pk)
+        quantity_diff = instance.quantity - original_transaction.quantity
+        instance.product.quantity -= quantity_diff
+        instance.product.save()

transactions/tests.py

@@ -0,0 +1,35 @@
+from django.test import TestCase
+from django.utils import timezone
+from .models import Transaction
+from stock.models import Gas
+
+class TransactionModelTest(TestCase):
+    def setUp(self):
+        self.gas = Gas.objects.create(name='Gas A', quantity=100,price=1.50)
+        self.transaction = Transaction.objects.create(
+            customer='John Doe',
+            quantity=10,
+            product=self.gas
+        )
+
+    def test_total_cost(self):
+        expected_total_cost = self.transaction.quantity * self.transaction.product.price
+        self.assertEqual(self.transaction.total_cost(), expected_total_cost)
+
+    def test_stock_reduction_on_create(self):
+        initial_quantity = self.gas.quantity
+        new_transaction = Transaction.objects.create(
+            customer='Jane Smith',
+            quantity=20,
+            product=self.gas
+        )
+        updated_quantity = self.gas.quantity
+        self.assertEqual(updated_quantity, initial_quantity - new_transaction.quantity)
+
+    def test_stock_reduction_on_update(self):
+        initial_quantity = self.gas.quantity
+        updated_quantity = 15
+        self.transaction.quantity = updated_quantity
+        self.transaction.save()
+        self.gas.refresh_from_db()
+        self.assertEqual(self.gas.quantity, initial_quantity - (updated_quantity - self.transaction.quantity))

transactions/urls.py

@@ -0,0 +1,11 @@
+from django.urls import path
+from . import views
+
+app_name = 'transactions'
+
+urlpatterns = [
+    path('', views.TransactionListView.as_view(), name='transaction_list'),
+    path('create/', views.TransactionCreateView.as_view(), name='transaction_create'),
+    path('<int:pk>/update/', views.TransactionUpdateView.as_view(), name='transaction_update'),
+    path('<int:pk>/delete/', views.TransactionDeleteView.as_view(), name='transaction_delete'),
+]

transactions/views.py

@@ -0,0 +1,25 @@
+from django.views.generic import ListView, CreateView, UpdateView, DeleteView
+from .models import Transaction
+from django.urls import reverse_lazy
+
+class TransactionListView(ListView):
+    model = Transaction
+    template_name = 'transactions/index.html'
+    context_object_name = 'transactions'
+
+class TransactionCreateView(CreateView):
+    model = Transaction
+    template_name = 'transactions/create.html'
+    fields = ['date', 'product', 'quantity', 'unit_cost']
+    success_url = reverse_lazy('transactions:transaction_list')
+
+class TransactionUpdateView(UpdateView):
+    model = Transaction
+    template_name = 'transactions/update.html'
+    fields = ['date', 'product', 'quantity', 'unit_cost']
+    success_url = reverse_lazy('transactions:transaction_list')
+
+class TransactionDeleteView(DeleteView):
+    model = Transaction
+    template_name = 'transactions/delete.html'
+    success_url = reverse_lazy('transactions:transaction_list')