from cx_Oracle import CLOB from django.contrib.gis.db.backends.base.adapter import WKTAdapter from django.contrib.gis.geos import GeometryCollection, Polygon class OracleSpatialAdapter(WKTAdapter): input_size = CLOB def __init__(self, geom): """ Oracle requires that polygon rings are in proper orientation. This affects spatial operations and an invalid orientation may cause failures. Correct orientations are: * Outer ring - counter clockwise * Inner ring(s) - clockwise """ if isinstance(geom, Polygon): if self._polygon_must_be_fixed(geom): geom = self._fix_polygon(geom) elif isinstance(geom, GeometryCollection): if any(isinstance(g, Polygon) and self._polygon_must_be_fixed(g) for g in geom): geom = self._fix_geometry_collection(geom) self.wkt = geom.wkt self.srid = geom.srid @staticmethod def _polygon_must_be_fixed(poly): return ( not poly.empty and ( not poly.exterior_ring.is_counterclockwise or any(x.is_counterclockwise for x in poly) ) ) @classmethod def _fix_polygon(cls, poly, clone=True): """Fix single polygon orientation as described in __init__().""" if clone: poly = poly.clone() if not poly.exterior_ring.is_counterclockwise: poly.exterior_ring = list(reversed(poly.exterior_ring)) for i in range(1, len(poly)): if poly[i].is_counterclockwise: poly[i] = list(reversed(poly[i])) return poly @classmethod def _fix_geometry_collection(cls, coll): """ Fix polygon orientations in geometry collections as described in __init__(). """ coll = coll.clone() for i, geom in enumerate(coll): if isinstance(geom, Polygon): coll[i] = cls._fix_polygon(geom, clone=False) return coll