Chapter 12. GeoDjango

The Django Python web framework was made available in 2005 and has been steadily supported and improved throughout the years. One major improvement was additional support for spatial data types and queries. This effort produced GeoDjango, allowing Django to support geospatial database models and web views that utilize geospatial queries.

GeoDjango is now a standard Django component, which can be activated using a specific configuration. In December 2017, Django 2 was released as the new long-term support version. It currently supports Python 3.4, 3.5, and 3.6.

In this chapter, we will learn about the following:

• Installation and configuration of Django and GeoDjango
• Django admin panel functionality, including map editing
• How to load shapefiles into database tables using LayerMapping
• GeoDjango queries
• Django URL patterns
• Django views

Installing and configuring Django and GeoDjango

Django, compared to Flask, is a batteries-included framework. It includes modules that allow for database backend support, without requiring a separate database code package (unlike Flask, which relies on SQLAlchemy). Django also includes an admin panel that allows for easy data editing and management through a web interface. This means fewer modules are installed and more code is included to handle database interactions and web processing.

There are some major differences between Flask and Django. Django separates URLs from views and models in a more structured manner than Flask. Django also uses Python classes for databases tables, but it has built-in database support. For geospatial databases, no extra module is required. Django also supports geometry columns in a wider range of databases, though PostgreSQL and PostGIS are used the most often. 

Like many Python 3 modules, Django development is geared towards Linux development environments...

Creating the application

This application will perform geospatial analysis using the geometry fields of database tables. To make this possible, we have to create and populate the database tables using shapefiles and a built-in method called LayerMapping.

The completed application will need URL pattern matching to link URLs with the views that will process the requests and return the response. Templates will be used to pass processed data to the browser. Views will be written to be able to handle both POST and GET requests and to redirect to other views.

Now that GeoDjango is configured, the NBA Arenas application can be created using the Django project management script called manage.py.

manage.py

The script manage.py performs a number of jobs to help set up and manage the project. For testing purposes, it can create a local web server (using runserver as the argument); it manages database schema migrations, generating tables from data models (using makemigration and migrate); it even has a...

Summary

Django, with its batteries-included philosophy, creates complete applications with very few outside libraries required. This application performs data management and data analysis using only the Django built-in tools and the GDAL/OGR library. Enabling the GeoDjango functionality is a relatively seamless experience because it is an integral part of the Django project.

Creating web applications with Django allows for a lot of instant functionality, including the administrative panel. The LayerMapping makes it easy to import data from shapefiles. The ORM model makes it easy to perform geospatial filters or queries. The templating system makes it easy to add web maps as well as location intelligence to a website.

In the next chapter, we will use a Python web framework to create a geospatial REST API. This API will accept requests and return JSON encoded data representing geospatial features.