GeoAlchemy 2 Documentation

Using SQLAlchemy with Spatial Databases.

GeoAlchemy 2 provides extensions to SQLAlchemy for working with spatial databases.

GeoAlchemy 2 focuses on PostGIS. PostGIS 1.5 and PostGIS 2 are supported.


GeoAlchemy 2 doesn’t currently support other dialects than PostgreSQL/PostGIS. Supporting Oracle Locator in the previous series was the main contributor to code complexity. So it is currently not clear whether we want to go there again.

GeoAlchemy 2 aims to be simpler than its predecessor, GeoAlchemy. Simpler to use, and simpler to maintain.


GeoAlchemy 2 requires SQLAlchemy 0.8. GeoAlchemy 2 does not work with SQLAlchemy 0.7 and lower.


GeoAlchemy 2 is available on the Python Package Index. So it can be installed with the standard pip or easy_install tools.

What’s New in GeoAlchemy 2

  • GeoAlchemy 2 supports PostGIS’ geometry type, as well as the geography and raster types.
  • The first series had its own namespace for spatial functions. With GeoAlchemy 2, spatial functions are called like any other SQLAlchemy function, using func, which is SQLAlchemy’s standard way of calling SQL functions.
  • GeoAlchemy 2 works with SQLAlchemy’s ORM, as well as with SQLAlchemy’s SQL Expression Language (a.k.a the SQLAlchemy Core). (This is thanks to SQLAlchemy’s new type-level comparator system.)
  • GeoAlchemy 2 supports reflection of geometry and geography columns.
  • GeoAlchemy 2 adds to_shape, from_shape functions for a better integration with Shapely.

See the Migrate to GeoAlchemy 2 page for details on how to migrate a GeoAlchemy application to GeoAlchemy 2.


GeoAlchemy 2 works with both SQLAlchemy’s Object Relational Mapping (ORM) and SQL Expression Language. This documentation provides a tutorial for each system. If you’re new to GeoAlchemy 2 start with this.


The code is available on GitHub:


Many thanks to Mike Bayer for his guidance and support! He also fostered the birth of GeoAlchemy 2.

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