Using the __geo_interface__ protocol

The __geo_interface__ protocol is a new protocol created by Sean Gillies and is targeted mainly at Python to provide a string representation of geographic data following Python's built-in protocols. The string representation for geographic data is basically GeoJSON.

Note

You can read more about this protocol at https://gist.github.com/sgillies/2217756.

Two developers, Nathan Woodrow and Martin Laloux, refined a version of this protocol for QGIS Python data objects. This recipe borrows from their examples to provide a code snippet that you can put at the beginning of your Python scripts to retrofit QGIS features and geometry objects with a __geo_interface__ method.

Getting ready

This recipe requires no preparation.

How to do it...

We will create two functions: one for features and one for geometry. We'll then use Python's dynamic capability to patch the QGIS objects with a __geo_interface__ built-in method. To do this, we need to perform the following...