Empty geometry name in read_arrow metadata

[kylebarron]

Testing out 0.5.0

from pyogrio.raw import read_arrow
metadata, table = read_arrow('nationalpark.geojson')
metadata
# {'crs': 'EPSG:4326',
#  'encoding': 'UTF-8',
#  'fields': array(['OBJECTID', 'UNIT_CODE', 'GIS_Notes', 'UNIT_NAME', 'DATE_EDIT',
#         'STATE', 'REGION', 'GNIS_ID', 'UNIT_TYPE', 'CREATED_BY',
#         'METADATA', 'PARKNAME', 'GlobalID', 'Shape__Are', 'Shape__Len',
#         'index_right'], dtype=object),
#  'geometry_type': 'Unknown',
#  'geometry_name': ''}

It looks like the column is always named wkb_geometry?

nationalpark.geojson.zip

[jorisvandenbossche]

Yeah, that's something I've also run into when implementing this (see the second last bullet point in the top post of https://github.com/geopandas/pyogrio/pull/155). When converting the Arrow result (like above) to a geopandas.GeoDataFrame, we also assume it is "wkb_geometry" if not in the metadata:

https://github.com/geopandas/pyogrio/blob/d8ea90315d7a7922bb07b249804aefbc8409f39c/pyogrio/geopandas.py#L163

But so it is not always "wkb_geometry", it can be a custom name, and then it will be listed in the metadata. I am not sure why OGR_L_GetGeometryColumn does not always return the name (I intended to ask about this upstream in GDAL, but didn't yet get to that).

But maybe we should fill in the metadata with "wkb_geometry" when it is now an empty string.

[kylebarron]

Thanks! I should read the docs closer 😉

If it will always be "wkb_geometry" if not otherwise stated, I think it would be helpful for clarity to include that in the geometry_name field in the metadata, rather than leaving it blank.

[jorisvandenbossche]

I think including the "wkb_geometry" instead of empty string is still a good idea?

[kylebarron]

For my own purposes, I'll plan to rely on the GeoArrow metadata, but I'm +1 on adding the string to the meta

[jorisvandenbossche]

Ah, yes, good point. But still useful to do anyway for other use cases, so going to leave it open for now