datasette-geojson

Add GeoJSON as an output option for datasette queries.

Installation

Install this plugin in the same environment as Datasette.

datasette install datasette-geojson

Usage

To render GeoJSON, add a .geojson extension to any query URL that includes a geometry column. That column should be a valid GeoJSON geometry.

For example, you might use geojson-to-sqlite or shapefile-to-sqlite to load neighborhood boundaries into a SQLite database.

wget -O neighborhoods.geojson https://opendata.arcgis.com/datasets/3525b0ee6e6b427f9aab5d0a1d0a1a28_0.geojson
geojson-to-sqlite boston.db neighborhoods neighborhoods.geojson --spatial-index # create a spatial index
datasette serve boston.db --load-extension spatialite

If you're using Spatialite, the geometry column will be in a binary format. If not, make sure the geometry column is a well-formed GeoJSON geometry. If you used geojson-to-sqlite or shapefile-to-sqlite, you should be all set.

Run this query in Datasette and you'll see a link to download GeoJSON:

select
  rowid,
  OBJECTID,
  Name,
  Acres,
  Neighborhood_ID,
  SqMiles,
  ShapeSTArea,
  ShapeSTLength,
  geometry
from
  neighborhoods
order by
  rowid
limit
  101

Note that the geometry column needs to be explicitly named geometry or you won't get the option to export GeoJSON. If you want to use a different column, rename it with AS: SELECT other AS geometry FROM my_table.

Development

To set up this plugin locally, first checkout the code. Then create a new virtual environment:

cd datasette-geojson
python3 -mvenv venv
source venv/bin/activate

Or if you are using pipenv:

pipenv shell

Now install the dependencies and tests:

pip install -e '.[test]'

To run the tests:

pytest