Theme: Development: presentation is focused on a specific technology, demonstrating either a new product or new developments in an existing product. GeoAlchemy is a powerful toolkit to use SQL spatial databases from Python. GeoAlchemy helps you use spatial databases from Python. GeoAlchemy provides extensions to SQLAlchemy, the Python SQL toolkit and ORM. GeoAlchemy builds on SQLAlchemy's extreme flexibility, and can be used for different types of applications, from simple scripts to complex web applications. In this talk we will present GeoAlchemy and SQLAlchemy. We will describe when and how SQLAlchemy and GeoAlchemy can be useful. We will demonstrate the power and flexibility of the tools. We will also present the new version of GeoAlchemy, namely GeoAlchemy 2. GeoAlchemy 2 enables leveraging PostGIS' new features. For example, GeoAlchemy 2 supports PostGIS's new raster type. Finally, we will demonstrate how GeoAlchemy integrates with other well-known Python tools, such as Shapely.

1. GEOALCHEMYhttp://erilem.net/talks/foss4g2013/geoalchemy.html

2. USE SQL SPATIAL DATABASES
FROM PYTHON

3. We have PostGIS. Hooray!

4. We have Python. Horray!

5. We need good ways/tools to
use PostGIS from Python.

6. That's the reason we're
developing GeoAlchemy

7. Wait! There's Django, and
GeoDjango!

8. YES (it's great), BUT...

9. There's a life outside Web and
Django!

10. Has anyone heard about Flask,
Bottle, Pyramid?
They're great frameworks, with lots of users.

11. They all love the SQLAlchemy
toolkit.
For good reasons!

12. SQLALCHEMY
The Database Toolkit for Python

13. SQLALCHEMY PHILOSOPHY
It's not about abstracting the DB
Abstracting is Hiding
It's about Automation
Instruct SQLA to do the grunt work we give it
Relational form of data is preserved
SQLA provides a rich vocabulary to express decisions
made by the developer

14. SQLALCHEMY CORE / ORM
SQLAlchemy has two distinct areas:
Core (SQL expression system)
Object Relational Mapper (ORM)

15. SQLALCHEMY QUERY EXAMPLE
The user whose email address is jack@google.com.
user = session.query(User).join(Address).
filter(Address.email_address=='jack@google.com').
one()

16. GEOALCHEMY
Thin layer above SQLAlchemy
With the same philosophy

17. GEOALCHEMY QUERY EXAMPLE
The lakes whose buffers have areas greater than 33.
It looks like SQLA!
It looks like PostGIS SQL!
lakes = session.query(Lake).filter(
Lake.geom.ST_Buffer(2).ST_Area() > 33).all()

18. SHAPELY INTEGRATION
to_shapeand from_shapefunctions
lake = session.query(Lake).filter(
Lake.geom.ST_Buffer(2).ST_Area() > 33).first()
lake_shape = to_shape(lake.geom)
lake_shape.representative_point().wkt

19. STATUS
Version 2 released 6 months ago (03/17/2013)
Benefits from SQLALchemy's latest advances
Improved API
Works both with SQLA Core and ORM
PostGIS 2 support (Raster included)
Fully documented and tested
https://geoalchemy-2.readthedocs.org

20. EXPOSURE
Used in production
Many client projects by Camptocamp
The SkyLines project ( )
By Tobias Bieniek (@Turbo87)
https://www.skylines-project.org)

21. THANKS!