add API for fetching most frequent ordered product and its tests

api_doc.txt

@@ -136,6 +136,22 @@ Inventory Report Endpoints:
    - Description: Get product order sales by certain period
    - Request Body: nil
    - Auth: Bearer token
+   - Response: 
+      {
+         "id": "21c7f528da",
+         "name": "Product beast",
+         "description": "Product beast Description",
+         "quantity": 4,
+         "price": 100,
+         "created_at": "2024-07-26T13:22:49.098161+01:00",
+         "updated_at": "2024-07-26T13:24:23.399251+01:00",
+         "owner": "Admin"
+      }
+
+3. GET /api/inventory/report/order/frequent
+   - Description: Get product ordered frequent with most quantity
+   - Request Body: nil
+   - Auth: Bearer token
    - Response: 
    [
       {

api_doc.txt.save

@@ -0,0 +1,145 @@
+API Descriptions:
+
+This application provides a RESTful API for Drugstoc Inventory Management BE Assessment.
+
+Auth Endpoints:
+
+1. POST /api/users/register/
+   - Description: Create a new user
+   - Request Body: name, email, password, password2, address
+   - Auth: Not required
+   - Response: name, email, password, password2, address
+
+Note: The register endpoint would create normal user account. To make a account an admin, a superuser would have to login to
+Django admin page and update the user account `is_admin` metadata to `true` and add `Admin` group for the user too.
+Then the normal user account turn to an admin that can add, update and delete products.
+
+2. POST /api/users/login/
+   - Description: login user
+   - Request Body: email, password
+   - Auth: Not required
+   - Response: id, metadata, refresh_token, access_token
+
+3. GET /api/users/profile
+   - Description: Retrieve user profile by access token provided
+   - Auth: Bearer token
+   - Response: all user fields
+
+4. POST /api/users/logout/
+   - Description: Logout auth user
+   - Request Body: refresh_token
+   - Auth: Bearer token
+   - Response: nil
+
+
+Inventory Products Endpoints:
+
+1. POST /api/inventory/products/add//
+   - Description: Create a new product by admin user
+   - Request Body: name, description, price, quantity, address
+   - Auth: Bearer token
+   - Response: id, owner, name, description, price, quantity, created_at, updated_at
+
+2. GET /api/inventory/products/
+   - Description: List products for an admin user
+   - Request Body: nil
+   - Auth: Bearer token
+   - Response: list of products
+
+3. PUT /api/inventory/products/:id/
+   - Description: Update product by an admin user
+   - Request Body: any field(s)
+   - Auth: Bearer token
+   - Response: id, owner, name, description, price, quantity, created_at, updated_at
+
+4. DELETE /api/inventory/products/:id/
+   - Description: Delete product published by an admin user
+   - Request Body: nil
+   - Auth: Bearer token
+   - Response: nil
+
+Note: This search functionality works when postgres database is used
+5. GET /api/inventory/products/search?q=
+   - Description: Search for products by the specified field
+   - Request Body: nil
+   - Auth: Bearer token
+   - Response: list of products
+   - Search From: title, description
+
+
+Inventory Orders Endpoints:
+
+1. POST /api/inventory/orders/
+   - Description: Create a new order
+   - Request Body: 
+   {
+    "items": [
+        {
+            "product": "0aa9ea8dce",
+            "quantity": 1
+        }
+    ]
+   }
+   - Auth: Bearer token
+
+   - Response: order fields data
+
+2. GET /api/inventory/orders/
+   - Description: List orders
+   - Request Body: nil
+   - Auth: Bearer token
+   - Response: list of orders
+   - Filters: status, date_from, date_to
+
+3. PUT /api/inventory/orders/:id/status/
+   - Description: Update order status by an admin user
+   - Request Body:
+   {
+    "status": "completed"
+   }
+   - Auth: Bearer token
+   - Response: order fields data
+
+4. DELETE /api/inventory/orders/:id/
+   - Description: Delete order
+   - Request Body: nil
+   - Auth: Bearer token
+   - Response: nil
+
+
+5. GET /api/inventory/orders/:id/
+   - Description: Get order detail
+   - Request Body: nil
+   - Auth: Bearer token
+   - Response: order data
+
+
+Inventory Report Endpoints:
+
+1. GET /api/inventory/report/stock/
+   - Description: Get product out of stock
+   - Request Body: nil
+   - Auth: Bearer token
+   - Response: 
+   [
+      {
+         "id": "0aa9ea8dce",
+         "name": "Product Name",
+         "quantity": 0,
+         "description": "Product Description",
+         "created_at": "2024-07-02T14:15:28.043625+01:00",
+         "updated_at": "2024-07-02T15:37:00.599740+01:00"
+      }
+   ]
+
+2. GET /api/inventory/report/sales/
+   - Description: Get product order sales by certain period
+   - Request Body: nil
+   - Auth: Bearer token
+   - Response: 
+   [
+      {
+         "date": "2024-07-02",
+         "total_sales": 400
+      }
+   ]

inventory/urls.py

@@ -2,7 +2,7 @@
 from django.urls import path
 from .views import (InventoryProductList, InventoryProductCreate,
      InventoryProductDetail,OrderListCreate, OrderDetail, OrderStatusUpdate,
-     LowStockReportView, SalesReportView, ProductSearchView)
+     LowStockReportView, SalesReportView, ProductSearchView, FrequentOrderedProductView)
 
 app_name = 'inventory'
 
@@ -15,6 +15,7 @@
     path('orders/<str:pk>/status/', OrderStatusUpdate.as_view(), name='order_status_update'),
     path('report/stock/', LowStockReportView.as_view(), name='low-stock-report'),
     path('report/sales/<str:period>/', SalesReportView.as_view(), name='sales-report'),
+    path('report/order/frequent', FrequentOrderedProductView.as_view(), name='frequent-ordered-product'),
     #Search will only functional with postgres database connection
     path('products/search', ProductSearchView.as_view(), name='products-search')
 ]

inventory/views.py

@@ -2,7 +2,7 @@
 import logging
 from django.contrib.postgres.search import SearchQuery, SearchRank
 from django_filters import rest_framework as filters
-
+from django.db import transaction
 from rest_framework import status, permissions
 from rest_framework.response import Response
 from rest_framework.views import APIView
@@ -270,4 +270,37 @@ def get(self, request):
 
         serializer = ProductSerializer(results, many=True)
         logger.info(f"Search results returned for query: {query}.")
-        return Response(serializer.data)
+        return Response(serializer.data)
+
+
+from django.db.models import Sum
+
+class FrequentOrderedProductView(APIView):
+
+    permission_classes = [permissions.IsAuthenticated]
+
+    def get(self, request, *args, **kwargs):
+        user = request.user
+        #returns the first instance of most frequent 9by quantity summation) ordered item product in the past
+        with transaction.atomic():
+            most_frequent_product = (
+                OrderItem.objects
+                    .filter(order__owner=user)
+                    .values('product')
+                    .annotate(total_quantity=Sum('quantity'))
+                    .order_by('total_quantity') #highest quantity down to least
+                    .first()
+            ) 
+            if most_frequent_product:
+                product = Product.objects.get(id=most_frequent_product['product'])
+                serializer = ProductSerializer(product)
+                return Response(
+                    {
+                        "product_name": serializer.data.get('name'),
+                        "total_quantity": serializer.data.get('quantity')
+                    }
+                )
+            else:
+                return Response({"detail": "No frequent ordered product found."}, status=404)
+
+

test/test_product.py

@@ -3,7 +3,7 @@
 from rest_framework.test import APIClient
 from users.models import User
 from django.contrib.auth import authenticate
-from inventory.models import Product
+from inventory.models import Product, Order, OrderItem
 
 
 @pytest.fixture
@@ -210,4 +210,32 @@ def test_order_detail(api_client, admin_user, product_data, get_token):
     assert len(detail_response.data) > 1  # Ensure the product is part of the order
 
 
+@pytest.mark.django_db
+def test_most_frequently_ordered_product(api_client, regular_user, product_data, get_token):
+    token = get_token(regular_user, 'user123')
+    api_client.credentials(HTTP_AUTHORIZATION='Bearer ' + token)
+
+    # Create products
+    product1 = Product.objects.create(owner=regular_user, **product_data)
+
+    # Create orders with order items
+    order1 = Order.objects.create(owner=regular_user)
+    order2 = Order.objects.create(owner=regular_user)
+
+    item1 = OrderItem.objects.create(order=order1, product=product1, quantity=3, price=product1.price)
+    item2 = OrderItem.objects.create(order=order2, product=product1, quantity=4, price=product1.price)
+
+    # Call the endpoint to get the most frequently ordered product
+    response = api_client.get('/api/inventory/report/order/frequent')
+    assert response.status_code == status.HTTP_200_OK
+    assert response.data['product_name'] == product1.name
+    assert response.data['total_quantity'] > item1.quantity
+
+@pytest.mark.django_db
+def test_no_orders_for_user(api_client, regular_user, get_token):
+    token = get_token(regular_user, 'user123')
+    api_client.credentials(HTTP_AUTHORIZATION='Bearer ' + token)
 
+    response = api_client.get('/api/inventory/report/order/frequent')
+    assert response.status_code == status.HTTP_404_NOT_FOUND
+    assert response.data['detail'] == "No frequent ordered product found."