In this tutorial, we are going to learn, step by step how to create a mobile application with an Ionic 3/Angular 5 front-end and a Python back-end. We'll be using Django and Django Rest Framework to build a simple REST API.
The app we'll be creating is a simple product tracker that can be used to keep track of the quantities of the products you have in stock. You'll be able to create products, increment and decrement their quantities.
In nutshell, we need to:
- create the Django project
- create the Django application
- design and create the database model(s)
- migrate the database
- generate the admin web interface to create, read, update and delete the database records
- create a super user
- generate a browsable and documented REST API with Django Rest Framework
- generate the Ionic 3 project
- create an Angular 5 CRUD service to interface with the REST API
- create an Ionic page to create and update products
- create an Ionic page to read the products
- add a method to delete products
Introduction to Django
Django is a Python-based web framework that encourages rapid development. It's used by many web developers create web applications using the Python language. Django has a plethora of features which makes it the most popular web framework among the Python community:
- Django has a clean and pragmatic design which can help you create complete prototypes in hours.
- Django packages or apps are very useful for code organization and reuse.
- You can either create your own apps or use community created apps to solve common web development problems without reinventing the wheel.
- You can quickly create APIs with powerful packages like Django Rest Framework and Tastypie.
- You can describe your domain models using a powerful ORM layer that saves you from dealing with SQL language.
- You can work and switch between different database relational management systems such as MySQL and PostgreSQL etc. without writing a single line of SQL.
- Django has a ready admin application than can be customized with your own Django models using a simple .register() method (You can use the admin app to generate a fully working CRUD application for your models).
- Django has a great and helpful community, a very good documentation and many tutorials on the web which can help you easily learn how to build your web application with Python.
Introduction to Django Rest Framework (DRF)
Django Rest Framework or DRF is a powerful Django application that allows you to build a full browsable and documented REST API from your database models. Thanks to DRF you can easily create an API to interface with multiple browser and mobile applications.
Django REST framework is a powerful and flexible toolkit for building Web APIs. Some reasons you might want to use REST framework: The Web browsable API is a huge usability win for your developers. Authentication policies including optional packages for OAuth1a and OAuth2. Serialization that supports both ORM and non-ORM data sources. Customizable all the way down - just use regular function-based views if you don't need the more powerful features. Extensive documentation, and great community support. --Source
You can install DRF using pip with:
pip install djangorestframework
Next you'll need to add it to your
INSTALLED_APPS = ( #... 'rest_framework', )
Introduction to Ionic
Getting Started with Django
In order to be able to build web applications with Django, you'll need to have a development environment with Python installed and optionally virtualenv which can be used to create isolated Pyhton environments for installing packages with different versions without any conflicts. You can install Python from the official Python website where you can find Python binaries for major operating systems.
virtualenv allows you to manage separate package installations for different projects. It essentially allows you to create a “virtual” isolated Python installation and install packages into that virtual installation. When you switch projects, you can simply create a new virtual environment and not have to worry about breaking the packages installed in the other environments. It is always recommended to use a virtualenv while developing Python applications.Source.
You can follow this guide to install virtualenv.
Now if everything is ready head back to your terminal or command prompt then create a new virtual environment then activate it using the following commands:
virtualenv env source env/bin/activate
Next you can install the latest version of Django using:
pip install django
You can then generate a new Django project using:
django-admin startproject producttracker
Next, navigate inside your project's root folder then create an application with:
cd producttracker python manage.py startapp products
Applications are used by Django to organize the project into reusable modules.
You'll need to open your project
settings.py and then add the application to the array of the installed apps
INSTALLED_APPS = [ 'django.contrib.admin', 'django.contrib.auth', 'django.contrib.contenttypes', 'django.contrib.sessions', 'django.contrib.messages', 'django.contrib.staticfiles', 'products' ]
Next you can create the database and run a local development server:
python manage.py migrate python manage.py runserver
A SQLite database file will be created in your project's root directory. You can change the database to any Django ORM supported RDBS such as MySQL or PostgreSQL anytime but for now let's stick with SQLite.
A local server will be launched. You can visit your web application by navigating, with your web browser, to http://localhost:8200.
Project Requirements and Database Design
Our simple stock tracker allows users to keep track of the products they have in stock. The user should be able to create products with an initial quantity then perform transactions to move products in and out of stock. Transactions are useful for keeping detailed information about stock movements. When a transaction is performed, the quantity of the associated product is either incremented (in) of decremented (out).
Each product belongs to a family and has a location so we need to be able to keep track of each product's family and location in stock.
So we can now design a simple database to meet these requirments. Open
products/models.py file then add these the following models:
A product has many properties such as: the title, the description, the unit's price, the SKU or the Stock Keeping Unit, the barcode (ISBN, UPC etc.), the quantity and the minimal quantity.
# -*- coding: utf-8 -*- from __future__ import unicode_literals from django.db import models class Product(models.Model): sku = models.CharField(max_length=13,help_text="Enter Product Stock Keeping Unit") barcode = models.CharField(max_length=13,help_text="Enter Product Barcode (ISBN, UPC ...)") title = models.CharField(max_length=200, help_text="Enter Product Title") description = models.TextField(help_text="Enter Product Description") unitCost = models.FloatField(help_text="Enter Product Unit Cost") unit = models.CharField(max_length=10,help_text="Enter Product Unit ") quantity = models.FloatField(help_text="Enter Product Quantity") minQuantity = models.FloatField(help_text="Enter Product Min Quantity") family = models.ForeignKey('Family') location = models.ForeignKey('Location') def get_absolute_url(self): """ Returns the url to access a particular instance of Product. """ return reverse('product-detail-view', args=[str(self.id)]) def __str__(self): return self.title
A family has a reference, a title and a description etc.
class Family(models.Model): reference = models.CharField(max_length=13, help_text="Enter family reference") title = models.CharField(max_length=200, help_text="Enter family title") description = models.TextField(help_text="Enter family description") unit = models.CharField(max_length=10,help_text="Enter family unit ") minq = models.FloatField(help_text="Enter family minimal quantity") def get_absolute_url(self): """ Returns the url to access a particular instance of Family. """ return reverse('family-detail-view', args=[str(self.id)]) def __str__(self): return self.title
A location has a reference, a title and a description
class Location(models.Model): reference = models.CharField(max_length=20, help_text="Enter Location Reference") title = models.CharField(max_length=200, help_text="Enter Location Title") description = models.TextField(help_text="Enter Location Description") def get_absolute_url(self): """ Returns the url to access a particular instance of Location. """ return reverse('family-detail-view', args=[str(self.id)]) def __str__(self): return self.title
A transaction has a date, a quantity, a cost and a reason (New Stock - Usable Return - Unusable Return) etc.
class Transaction(models.Model): sku = models.CharField(max_length=13,help_text="Enter SKU") barcode = models.CharField(max_length=13,help_text="Enter barcode (ISBN, UPC etc.)") comment = models.TextField(help_text="Enter a comment") cost = models.FloatField(help_text="Enter unit cost") quantity = models.FloatField(help_text="Enter quantity") product = models.ForeignKey('Product') date = models.DateField(null=True, blank=True) REASONS = ( ('ns', 'New Stock'), ('ur', 'Usable Return'), ('nr', 'Unusable Return'), ) reason = models.CharField(max_length=2, choices=REASONS, blank=True, default='ns', help_text='Reason for transaction') def get_absolute_url(self): """ Returns the url to access a particular instance of transaction. """ return reverse('transaction-detail-view', args=[str(self.id)]) def __str__(self): return 'Transaction : %d' % (self.id)
Now that we have defined our database models. Let's register them with the admin application.
Registering the Models with The Admin Application
The Django admin can use your models to auto-create a web interface which allows you to add, read, update and delete records. In order to tell Django about our newly created models. Open the products/admin.py file then copy the following code to import and register the database models:
# -*- coding: utf-8 -*- from __future__ import unicode_literals from django.contrib import admin from .models import Product ,Family ,Location ,Transaction admin.site.register(Product) admin.site.register(Family) admin.site.register(Location) admin.site.register(Transaction)
Now to access the admin web interface we need to create a super user so head back to your terminal and run the following command:
python manage.py createsuperuser
Enter the credentials you want to use then hit Enter.
Next go to http://localhost:8200/admin then login with your credentials. You can now use the admin interface to create records for different models we created before.
Now that we have created the models and registered them with the admin application we can go ahead and create the REST API.