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 2 and PostGIS 3 are supported.

GeoAlchemy 2 also supports the following dialects:

Note that using GeoAlchemy 2 with these dialects may require some specific configuration on the application side.

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

The current version of this documentation applies to the version 0.15.1 of GeoAlchemy 2. See the GeoAlchemy 2 Changelog page for details on recent changes.

Requirements

GeoAlchemy 2 requires SQLAlchemy >= 1.4.

Installation

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.

Tutorials

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.

Use with Alembic

The GeoAlchemy 2 package is compatible with the migration tool Alembic. The Use Alembic with GeoAlchemy 2 page provides more details on this topic.

Reference Documentation

Development

The code is available on GitHub: https://github.com/geoalchemy/geoalchemy2.

Contributors:

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

Citation

When you use this software, we kindly ask you to cite the following DOI:

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