How to write non-spatial records to GPKG?

[mangecoeur]

Expected behavior and actual behavior.

The GPKG format allows to also add records without spatial data, however it's not clear how this can be done in fiona. Simply ommiting the geometry field causes an error (See below). Adding a geometry field with a value of None instead adds a geometry column filled with None

Steps to reproduce the problem.

crs = fiona.crs.from_epsg(4326)
schema = {'properties': {'schema_version': 'int',
  'source': 'str',
  'heating_degree_days': 'float',
  'cooling_degree_days': 'float'}}

data = {'properties': {'schema_version': 1,
  'source': 'OneBuilding TMY',
  'heating_degree_days': 3322.016666666667,
  'cooling_degree_days': 6781.799999999999}}

with fiona.open("package.gpkg", 'w', driver='GPKG', crs=crs, schema=schema, layer='climate',
                OVERWRITE='YES',
                SPATIAL_INDEX='NO'
                ) as package:
    package.write(data)

Result

File ~/Code/geneap/.venv/dev/lib/python3.10/site-packages/fiona/collection.py:568, in Collection.write(self, record)
    562 def write(self, record):
    563     """Stages a record for writing to disk.
    564     
    565     Note: Each call of this method will start and commit a
    566     unique transaction with the data source.
    567     """
--> 568     self.writerecords([record])

File ~/Code/geneap/.venv/dev/lib/python3.10/site-packages/fiona/collection.py:558, in Collection.writerecords(self, records)
    556 if self.mode not in ("a", "w"):
    557     raise OSError("collection not open for writing")
--> 558 self.session.writerecs(records, self)
    559 self._len = self.session.get_length()
    560 self._bounds = None

File fiona/ogrext.pyx:1396, in fiona.ogrext.WritingSession.writerecs()

AttributeError: 'dict' object has no attribute 'properties'

Fiona and GDAL version and provenance

Fiona 1.9.3 from pip, GDAL from homebrew

[mangecoeur]

Diving into the code, the error I get comes from the way fiona encodes the input record in model.py. If the record does not have a 'type' field the input dict is returned as is instead of converting to a Feature or Geometry object, but the write() method then tries to access a properties field that doesn't exist.

Adding a 'type:feature' field avoids the error but the table is then still written as 'spatial' with a geom field set to null, rather than a non-spatial table. I'm not sure what the GPKG standard say but I think this is not the intended behaviour.

crs = fiona.crs.from_epsg(4326)
schema = {
    'type': 'Feature',
    'properties': {'schema_version': 'int',
  'source': 'str',
  'heating_degree_days': 'float',
  'cooling_degree_days': 'float'}}

data = {
    'type': 'Feature',
    'properties': {'schema_version': 1,
  'source': 'OneBuilding TMY',
  'heating_degree_days': 3322.016666666667,
  'cooling_degree_days': 6781.799999999999}}

with fiona.open("package.gpkg", 'w', driver='GPKG', crs=crs, schema=schema, layer='climate',
                OVERWRITE='YES',
                SPATIAL_INDEX='NO'
                ) as package:
    package.write(data)

[sgillies]

@mangecoeur Fiona doesn't permit reading and writing non spatial data. It's not this way intentionally, but I am reluctant to add this because I don't want users to begin to depend on fiona for something that it isn't even second best at. It's my recommendation that one use, for example, sqlite3 for managing complex Geopackage databases.

That said, I'm not very opposed to letting fiona write non-spatial tables if the changes to the codebase aren't complicating, and I'd be happy to review a PR.

[mangecoeur]

Makes sense, AFAIU the GDAL GPKG driver should allow writing non spatial tables, so I think its possible without adding complexity. I will see if I can make it work.