Purchase Order Project

Overview

This Django project provides a CRUD API for managing purchase orders, suppliers, and line items. The API is built using Django, Django Rest Framework (DRF), and PostgreSQL.

Database Models

Supplier

• Fields:
  • name: String
  • email: Email field

LineItem

• Fields:
  • item_name: String
  • quantity: Positive integer
  • price_without_tax: Decimal field
  • tax_name: String
  • tax_amount: Decimal field
  • line_total: Calculated field (quantity * price_without_tax).

PurchaseOrder

• Fields:
  • supplier: Foreign key to Supplier.
  • order_time: Date and time
  • order_number: Positive integer
  • total_quantity: Calculated field (sum of quantities of line items).
  • total_amount: Calculated field (sum of line_total of line items).
  • total_tax: Calculated field (sum of tax_amount of line items).

API Endpoints

Purchase Orders

• List and Create: GET and POST requests to /api/purchase/orders/
• Retrieve, Update, and Delete: GET, PUT, and DELETE requests to /api/purchase/orders/<int:id>/

Setup Instructions

Prerequisites

• Python 3.x
• Pip (Python package installer)
• PostgreSQL

Installation

1. Clone the repository:

   git clone https://github.com/your-username/purchase_order_project.git

2. Navigate to the project directory:

   cd purchase_order_project

3. Create a virtual environment (optional but recommended):

   python -m venv venv

4. Activate the virtual environment:

   • On Windows:

     venv\Scripts\activate

   • On Unix or MacOS:

     source venv/bin/activate

5. Install project dependencies:

   pip install -r requirements.txt

Database Configuration

1. Create a PostgreSQL database for the project.

   You can create a free tier postgresql instance from https://neon.tech/ OR use a local postgresql installation

2. Update the database settings in purchase_order_project/settings.py:

   • For local PostgreSQL installation

     DATABASES = {
         'default': {
             'ENGINE': 'django.db.backends.postgresql',
             'NAME': 'your_database_name',
             'USER': 'your_database_user',
             'PASSWORD': 'your_database_password',
             'HOST': 'localhost',
             'PORT': '5432',
         }
     }

   • For neon.tech PostgreSQL instance

     DATABASES = {
         'default': {
             'ENGINE': 'django.db.backends.postgresql',
             'NAME': 'your_database_name',
             'USER': 'your_database_user',
             'PASSWORD': 'your_database_password',
             'HOST': '******.aws.neon.tech',
             'PORT': '5432',
             'OPTIONS': {'sslmode': 'require'},
         }
     }

Migrations

Apply the initial database migrations:

python manage.py makemigrations
python manage.py migrate

**By default a migrated neon.tech postgress instance is used, you do not need to apply the above migrations if you are using that.

Running the Development Server

Start the Django development server:

python manage.py runserver

The API will be accessible at http://127.0.0.1:8000/.

Accessing Swagger and ReDoc Documentation

• Swagger: Open http://127.0.0.1:8000/swagger/ in your web browser.

• ReDoc: Open http://127.0.0.1:8000/redoc/ in your web browser.

Running Tests

To run the unit tests:

python manage.py test 

Auto-generating OpenAPI Spec

To auto-generate the OpenAPI spec using Django Spectacular:

python manage.py spectacular --file schema.yml

This will create a file named schema.yml containing the OpenAPI spec.

Testing API Endpoints

Import the PurchaseOrderProject.postman_collection.json in Postman