Marc Compte
GIS lover. Web developer. Working at the GIS Service in the University of Girona (http://udg.edu/sigte) and freelance.
Building custom web administrators for geographic data driven websites with Django
Marc Compte
University of Girona (SIGTE)
Django
Talks @ GeoPython
by Paolo Melchiorre
in Room 2
on 23rd april @ 11:45
Maps with Django
by Megan Luisa White
in Room 1
on 23rd april @ 21:00
Cal ToxTrack
GeoDjango
Use case
Django
Django makes it easier to build better Web apps more quickly and with less code.e.
Django is a high-level Python Web framework that encourages rapid development and clean, pragmatic design. Built by experienced developers, it takes care of much of the hassle of Web development, so you can focus on writing your app without needing to reinvent the wheel. It’s free and open source.
What is it?
Django
Why Django?
Django
Features (some)
- MVC paradigm
- HTML Templates (jinja2 like)
- Integrated web server
- i18n and l10n ready
- Caching & Logging
- URL management (routing)
- CLI custom commands
- Backup&restore
- Admin!!
- Object-Relational Mapping!!
+ Loads of third-party modules
Django Admin
What is it?
It’s not just scaffolding – it’s the whole house.e.
It’s the backend templates, the views, forms, controllers and even some models out-of-the-box without typing a single line.
Django Admin
0 lines of code
$ pip install django $ django-admin startproject demo $ django-admin startapp app $ python manage.py migrate $ python manage.py createsuperuser $ python manage.py runserver
+
Django Admin
0 lines of code
Django Admin
0 lines of code
Django Admin
Adding new models (tables)
Django Admin
Adding new models (tables)
$ python manage.py makemigrations
$ python manage.py migrate
+
+
Django Admin
Adding new models (tables)
Django Admin
Adding new models (tables)
Django Admin
Tune up with one-liners
Django Admin
Tune up with one-liners
Django Admin
Tune up with one-liners
Django Admin
Tune up with one-liners
Django Admin
Tune up with one-liners
Django Admin
Other tune-ups: inlines
Django Admin
Adding geometries
GeoDjango
django-geojson + django-leaflet
Spatial databases
Non-spatial databases
Django Admin
Adding geometries
| GeoDjango | GeoJSON+Leaflet | |
|---|---|---|
| Database | Spatial | Non-spatial |
| Field | Geometry | JSON |
| Spatial operations | Included | Requires modules |
| ORM integration | Yes | No |
| Spatial indexing | Yes | No |
Django Admin
Adding geometries as JSON fields
(env)$ pip install django-geojson jsonfields django-leaflet
Add geom field to model
Django Admin
Adding geometries as JSON fields
Add leaflet map widget to the ModelAdmin
Django Admin
Creating geometries from the admin
Django Admin
Legacy databases
(env)$ python manage.py inspectdb > app/models.py
DATABASES = {
'default': {
'ENGINE': 'django.db.backends.postgresql_psycopg2',
'NAME': 'my_db_name',
'USER': 'my_user',
'PASSWORD': 'my_password',
'HOST': 'my_server',
'PORT': '5432',
}
}
settings.py
Django ORM
SQL is an English-like language
>>> from .models import ObjectA
>>> all_as = ObjectA.objects.all()
SELECT * FROM ObjectA;
>>> filtered = ObjectA.objects.filter( ... a_string='Test' ... )
>>> filtered2 = ObjectA.objects.filter( ... a_number__gte=10 ... )
SELECT * FROM ObjectA WHERE ...;
Django ORM
>>> filtered = ObjectA.objects.filter( ... objectb__field1='Test' ... )
SELECT ObjectA.* FROM ObjectA, ObjectB WHERE ObjectA.objectb = ObjectB.id AND ObjectB.field1 = 'Test';
Is SQL an English-like language?
Django ORM
>>> filtered = Publication.objects.select_related(
... 'country', 'country_state', 'city'
... ).values(
... 'id', 'title', 'country__country_name',
... 'countrystate__name', 'city__name'
... )
SELECT publication.id, publication.title, country.country_name, countrystate.name, city.name
FROM publication
INNER JOIN country ON ( publication.country_id = country.id )
INNER JOIN countrystate ON ( publication.countrystate_id = countrystate.id )
INNER JOIN city ON ( publication.city_id = city.id );
This is not an Enligsh-like sentence any more
Django ORM
>>> filtered = Publication.objects.all() >>> for item in filtered: ... print(item.id, item.title, ... item.country.country_name, ...)
SELECT publication.id, publication.title, country.country_name, countrystate.name, city.name
FROM publication
INNER JOIN country ON ( publication.country_id = country.id )
INNER JOIN countrystate ON ( publication.countrystate_id = countrystate.id )
INNER JOIN city ON ( publication.city_id = city.id );
Caveats
Django ORM
>>> filtered = ObjectA.objects.exclude( ... a_string__contains='Test' ... ) >>> for item in filtered: ... # do something >>> filtered2 = filtered.filter( ... a_number__gte=10, ... a_date__gte=date,
... a_date__lte=another_date, ... geom__intersects=geometry ... )
>>> for item in filtered2: ... # do something
Reusing queries
Other benefits
Django ORM
Versatility
Why it is better
Security
Readability
Questions?
Web admins for mapping sites with Django
By Marc Compte
Web admins for mapping sites with Django
Building custom web administrators for geographic data driven websites with Django.
