GeoConverters does only support polygons with one hole?

[cblust]

Hi all,

I currently try to read a GeoJsonPolygon with two holes from the database. In the db its correctly persisted with three items in the coordinates array (one outer and two inner rings).

However, when reading, it seems that only the first hole is considered. This issue was already discussed in #4104 with the same remark in the end. I am not sure if it was not implemented for a specific reason or missed?

Kind regards
Chris

[DragonFSKY]

Hi,

I would be happy to help with this issue if the maintainers think this is a reasonable area for contribution.

I looked into the related history around #4104 and #4156. From what I understand, the previous change added support for reading a GeoJsonPolygon with an inner ring from a MongoDB Document. However, the current GeoConverters.toGeoJsonPolygon(…) implementation still only applies dbList.get(1) as the inner ring:

• dbList.get(0) is converted as the outer ring.
• dbList.get(1) is converted as the first inner ring.
• Additional rings such as dbList.get(2) and later are not applied.

So my current understanding is that polygons without holes and polygons with a single hole are handled correctly, but polygons with multiple inner rings lose the additional inner rings during Document to GeoJsonPolygon conversion.

If this analysis is correct, I would like to keep the fix narrowly scoped to the GeoConverters conversion path:

• keep the existing behavior for polygons without inner rings;
• keep the existing behavior for polygons with one inner ring;
• extend the conversion to apply all remaining coordinate rings as inner rings;
• add unit tests for a polygon with multiple inner rings;
• also cover the GeoJsonMultiPolygon path if appropriate, since it reuses the same conversion method.

I would avoid changing the GeoJsonPolygon model itself, as it already seems to support multiple inner rings via withInnerRing(…).

Please let me know if this direction makes sense, or if there is historical context that I may have missed.

Thanks.