Allow drawing on a map on table pages for tables with a geometry column

[simonw]

Refs #7, simonw/datasette#473 and simonw/datasette#1559

Still needed:

• Run JavaScript on table page (if a geometry column is present) and show the map
• Release of Datasette with the new filters_from_request plugin hook that this uses
• Tests
• Updated documentation

[simonw]

Tests are failing because from datasette.filters import FilterArguments only works if you are running against the Datasette branch with that feature in.

[simonw]

Not sure why that fix didn't work.

[simonw]

OK, this works pretty well:

[simonw]

The tests are a bit tricky because ideally I'd like to have SpatiaLite installed so I can test the new geometry_columns_for_table function.

geojson-to-sqlite has a solution for this, it's actually nice and simple: https://github.com/simonw/geojson-to-sqlite/blob/13c4e5ac0b7b6551e88432fe0e9e108bde0208f4/.github/workflows/test.yml#L24-L26

    - name: Install SpatiaLite
      run: |
        sudo apt-get install libsqlite3-mod-spatialite

[simonw]

Can depend on this 0.60a0 alpha release now: https://docs.datasette.io/en/latest/changelog.html#a0-2021-12-17

[simonw]

What's the quickest way to programmatically create a valid SQLite database geometry table with and without a spatial index configured I wonder?

https://github.com/simonw/geojson-to-sqlite probably.

[simonw]

In this:

SELECT AddGeometryColumn('mytable', 'geometry', 4326, 'POINT', 'XY');

That XY means "2 dimensional".

[simonw]

Just found this script: https://github.com/simonw/datasette/blob/0a7621f96f8ad14da17e7172e8a7bce24ef78966/tests/build_small_spatialite_db.py