[gdal-dev] Geometry column name: Field 'OGR_GEOMETRY' not found in source layer

[Jorge Gustavo Rocha]

Hi,

Only now, based on Even's answer, I was able to find the proper
documentation. My fault! I was searching using uppercase and git grep
"_OGR_GEOMETRY_" was returning nothing.

Just an update regarding the documentation:

1) OGR_GEOMETRY is well documented at
https://gdal.org/user/ogr_sql_dialect.html#ogr-geometry

2) "_OGR_GEOMETRY_" is also pretty well documented in the same document,
at https://gdal.org/user/ogr_sql_dialect.html#geometry-field

3) As an alternative for all drivers, GEOMETRY field, used in SQL SQLite
dialect, is well documented at
https://gdal.org/user/sql_sqlite_dialect.html#geometry-field

Regards,

Jorge

Às 22:36 de 19/11/20, Jorge Gustavo Rocha escreveu:
> Hi Even,
> 
> Thanks for the feedback. The difference you mentioned is well understood
> with the example:
> 
> -sql 'select OGR_GEOMETRY, "_OGR_GEOMETRY_" from layer'
> 
> I get exactly what is expected from both fields:
> 
> POLYGON | POLYGON(...)
> POLYGON | POLYGON(...)
> 
> It would be nice to allow "_OGR_GEOMETRY_" in ogr2ogr -select, but the
> usage of -sql works.
> 
> To make the usage of this "_OGR_GEOMETRY_" more clear, may I add an
> example to https://gdal.org/programs/ogrinfo.html?
> 
> I think this is not well documented. The only reference I used [1] is
> not accurate anymore. It says:
> 
> "the special field names “OGR_GEOMETRY” and “OGR_STYLE” will be
> interpreted to refer to the geometry and style values of a feature".
> 
> Regards,
> 
> Jorge
> 
> [1]
> https://gdal.org/development/rfc/rfc29_desired_fields.html?highlight=ogr_geometry
> 
> 
> Às 18:27 de 19/11/20, Even Rouault escreveu:
>> Jorge,
>>
>>> To get only the geometry column from a shapefile, I can do:
>>>
>>> ogrinfo cidade.shp -sql "select OGR_GEOMETRY from cidade"
>>
>> This is a bit a misnomer: OGR_GEOMETRY is a special keyword to get the 
>> geometry *type* of a geometry ("POLYGON", "POINT", "LINESTRING"), not the 
>> geometry itself. For that, for format such as shapefile which don't have a 
>> named geometry column, you must use the "_OGR_GEOMETRY_" (quoted with double 
>> quotes as starting with underscore)
>>
>>> But this column name is not allowed in the -select option on ogr2ogr:
>>>
>>> ogr2ogr -overwrite -skipfailures -update PG:service=estarreja cidade.shp
>>> -select OGR_GEOMETRY
>>
>> you can use -sql here as well
>>
>> Could perhaps make sense to support the special "_ogr_geometry_" field here 
>> too
>>
>> Even
>>
> 

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