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https://github.com/russss/datasette-geo

A Datasette plugin to make Spatialite databases effortlessly explorable
https://github.com/russss/datasette-geo

datasette geojson geospatial mapbox-gl-js maps python sqlite

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A Datasette plugin to make Spatialite databases effortlessly explorable

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# Datasette Geo



**Work in progress. Don't expect this to work yet, especially since it depends on a lot of unmerged Datasette features.**



A [Datasette](https://github.com/simonw/datasette) plugin to make [Spatialite](https://www.gaia-gis.it/fossil/libspatialite/index) databases effortlessly explorable.



## Features

* [All the good stuff from Datasette](https://datasette.readthedocs.io/en/stable/)

* Better representation of Spatialite geometries in table views

* Fast, scalable map viewing using Mapbox GL and an integrated Mapbox Vector Tile server

* GeoJSON export endpoints

* Maybe more?



![Datasette Geo Screenshot](doc/screenshot.png)



## Installation

As covered above, please don't try to install this yet. It currently relies on a raft of patches to Datasette, which will

hopefully be merged soon.



## Database Preparation

The database you're using needs to have the geographic data stored in Spatialite geometry columns. These columns must be indexed, which you can do with the following SQL:

```sql

	SELECT CreateSpatialIndex('table_name', 'column_name');

```



## Configuration



You'll need to make sure the Spatialite module is loaded by Datasette, [as described in the docs](https://datasette.readthedocs.io/en/stable/spatialite.html).



After this, Datasette Geo should work out of the box, automatically detecting the Spatialite column in your tables

and rendering them. You may want to increase your `sql_time_limit_ms` configuration setting to allow enough time for

large vector tiles to be rendered.



## Base Maps

By default, Datasette Geo uses the standard [OpenStreetMap](https://openstreetmap.org) raster tiles as a base map, as they require no authentication to access. Please note if you deploy Datasette Geo with these tiles, you must comply with the OSM

[Tile Usage Policy](https://operations.osmfoundation.org/policies/tiles/).



Raster tiles are not as fast and pretty as using a vector tile source, so you can configure Datasette Geo to use

a vector tile source instead. Note that (to my knowledge) all available vector tile services are paid services although

Mapbox and MapTiler have free tiers:



### Mapbox

You'll need a Mapbox account so you can fetch an [access token](https://account.mapbox.com/access-tokens/). 

You'll also need a style URL, which can either be one of Mapbox's [default styles](https://docs.mapbox.com/api/maps/#mapbox-styles)

or a custom style generated with [Mapbox Studio](https://studio.mapbox.com/).



Configure it in your `metadata.json`:

```json

    "plugins": {

	    "datasette-geo": {

		"mapbox_token": "",

		"style": "mapbox://styles/mapbox/light-v10"

	    }

    }

```

### MapTiler

[MapTiler](https://maptiler.com) is another source of vector tile data which is cheaper than Mapbox. By way of full disclosure,

they currently sponsor some of my personal projects with free vector tile access.



[Choose your map](https://cloud.maptiler.com/maps/) and you'll be given a vector style URL:

```json

    "plugins": {

	    "datasette-geo": {

		"style": "https://api.maptiler.com/maps/positron/style.json?key="

	    }

    }

```



### Custom Style File

You can generate a custom [Mapbox GL style file](https://docs.mapbox.com/mapbox-gl-js/style-spec/) using a tool like

[Maputnik](https://maputnik.github.io/), or by hand-writing it if you're especially keen. Note that you will

still need to define a tile source in the style file. Add it to your Datasette project static directory, and reference it in `metadata.json`

like so:

```json

    "plugins": {

	    "datasette-geo": {

		"style": "/static/mystyle.json"

	    }

    }

```