Item bbox field should be nullable in the sqlalchemy backend

[yellowcap]

Problem

I have some trouble with the item bbox field when ingesting STAC items that have a null value on the geometry field. The STAC spec allows the item bbox to be null, when the geometry field is null, but in the sqlalchemy backend the bbox is not nullable.

Example STAC Item with a null geometry and no bbox

I came across this problem when trying to ingest STAC Item data from the usgs-landsat stac api.

In this api, there are some items that have geometry set to null and omit the bbox field. Here is a link to an example:

https://landsatlook.usgs.gov/stac-server/collections/landsat-c2l3-ba/items/LE07_CU_002012_20150101_20210502_02_BA

Proposed solution

I would like to propose to make the bbox field nullable in the items table. This would increase the compliance with the STAC spec.

[geospatial-jeff]

@yellowcap Good catch! We'll have to start with an upstream change to stac-pydantic, I created an issue there!

[yellowcap]

Excellent, thanks @geospatial-jeff . I had a go at the stac-pydantic change. But I think that we need to go one layer up, as the geometry field is defined in geojson-pydantic here: https://github.com/developmentseed/geojson-pydantic/blob/master/geojson_pydantic/features.py#L19