fixes

Author: timgraham

django_mongodb_backend_gis/operations.py

@@ -68,36 +68,41 @@ def geo_db_type(self, f):
         return "object"
 
     def get_geometry_converter(self, expression):
+        srid = expression.output_field.srid
+
         def geom_from_coordinates(geom_class, coordinates):
             is_polygon = geom_class.__name__ == "Polygon"
-            return geom_class(*coordinates if is_polygon else coordinates, srid=4326)
+            return geom_class(*coordinates if is_polygon else coordinates, srid=srid)
 
         def converter(value, expression, connection):  # noqa: ARG001
             if value is None:
                 return None
+
             geom_class = getattr(geos, value["type"])
             if geom_class.__name__ == "GeometryCollection":
                 return geom_class(
                     [
                         geom_from_coordinates(getattr(geos, v["type"]), v["coordinates"])
                         for v in value["geometries"]
                     ],
-                    srid=4326,
+                    srid=srid,
                 )
             if issubclass(geom_class, geos.GeometryCollection):
-                # TODO: confirm this is correct.
+                sub_geom_class = geom_class._allowed
+                # MultiLineString allows both LineString and LinearRing but should be
+                # initialized with LineString.
+                if isinstance(sub_geom_class, tuple):
+                    sub_geom_class = sub_geom_class[0]
                 return geom_class(
                     [
-                        # TODO: For MultiLineString, geom_class._allowed is a
-                        # tuple so this will crash.
-                        geom_class._allowed(
+                        sub_geom_class(
                             *value["coordinates"][x]
                             if geom_class.__name__ == "MultiPolygon"
                             else value["coordinates"][x]
                         )
                         for x in range(len(value["coordinates"]))
                     ],
-                    srid=4326,
+                    srid=srid,
                 )
             return geom_from_coordinates(geom_class, value["coordinates"])