django/django · error · GDALException

Cannot create OGR Geometry from input: %s

Error message

Cannot create OGR Geometry from input: %s

What it means

Raised by OGRGeometry.__init__ after the underlying GDAL/OGR C library returned a null geometry pointer despite the input passing Python-level type checks. The input was recognized as WKT, WKB, GeoJSON, GML, or a type name, but OGR could not parse it into a real geometry, so Django treats the construction as failed. It is a GDALException signaling malformed or semantically invalid geometry input.

Source

Thrown at django/contrib/gis/gdal/geometries.py:122

        elif isinstance(geom_input, memoryview):
            # WKB was passed in
            g = self._from_wkb(geom_input)
        elif isinstance(geom_input, OGRGeomType):
            # OGRGeomType was passed in, an empty geometry will be created.
            g = capi.create_geom(geom_input.num)
        elif isinstance(geom_input, self.ptr_type):
            # OGR pointer (c_void_p) was the input.
            g = geom_input
        else:
            raise GDALException(
                "Invalid input type for OGR Geometry construction: %s"
                % type(geom_input)
            )

        # Now checking the Geometry pointer before finishing initialization
        # by setting the pointer for the object.
        if not g:
            raise GDALException(
                "Cannot create OGR Geometry from input: %s" % geom_input
            )
        self.ptr = g

        # Assigning the SpatialReference object to the geometry, if valid.
        if srs:
            self.srs = srs

        # Setting the class depending upon the OGR Geometry Type
        if (geo_class := GEO_CLASSES.get(self.geom_type.num)) is None:
            raise TypeError(f"Unsupported geometry type: {self.geom_type}")
        self.__class__ = geo_class

    # Pickle routines
    def __getstate__(self):
        srs = self.srs
        if srs:
            srs = srs.wkt

View on GitHub (pinned to ae25a40be0)

Solutions

  1. Validate the input string against the expected format (wkt_regex / hex_regex / json_regex) before constructing OGRGeometry.
  2. Catch GDALException around the constructor and report the offending input back to the user instead of crashing.
  3. Re-serialize the geometry from a trusted source (e.g. re-export from PostGIS as EWKB/EWKT) to eliminate truncation or encoding corruption.
  4. For WKB, verify len(geom_input) matches the declared WKB size header before calling OGRGeometry.

Example fix

// before
geom = OGRGeometry(user_wkt)  # may raise GDALException

// after
from django.contrib.gis.geometry import wkt_regex
if not (isinstance(user_wkt, str) and wkt_regex.match(user_wkt)):
    raise ValueError(f"Not valid WKT: {user_wkt!r}")
geom = OGRGeometry(user_wkt)
Defensive patterns

Strategy: validation

Validate before calling

from django.contrib.gis.geometry import wkt_regex, hex_regex, json_regex

def is_valid_ogr_text_input(s: str) -> bool:
    if not isinstance(s, str):
        return False
    return bool(wkt_regex.match(s) or json_regex.match(s) or hex_regex.match(s))

if not is_valid_ogr_text_input(user_input):
    raise ValueError(f'Refusing to construct OGRGeometry from invalid input: {user_input!r}')
geom = OGRGeometry(user_input)

Type guard

def is_valid_ogr_text_input(s) -> bool:
    from django.contrib.gis.geometry import wkt_regex, hex_regex, json_regex
    return isinstance(s, str) and bool(
        wkt_regex.match(s) or json_regex.match(s) or hex_regex.match(s)
    )

Try / catch

from django.contrib.gis.gdal import GDALException
try:
    geom = OGRGeometry(user_input)
except GDALException as e:
    raise ValueError(f'Invalid geometry input from user: {user_input!r}') from e

Prevention

When it happens

Trigger: Constructing OGRGeometry with malformed WKT ('PONT(1 2)'), truncated/corrupt WKB bytes, GeoJSON missing coordinates, an unparseable GML string, or a short-hand string that passes the regex/type-name branch but yields a null OGR pointer (geometries.py:121).

Common situations: Loading user-supplied or third-party shapefile/GeoJSON data with typos; feeding EWKT produced by PostGIS that OGR cannot parse; passing a WKB buffer truncated by a bad db column read; copy-pasting WKT with swapped/mismatched parentheses.

Related errors

AI-assisted analysis of django/django@ae25a40be0 (2026-08-06). Data as JSON: /api/errors/7169b0078dff37b1. Report an issue: GitHub.