BUG: Fix pickling for CRS builder classes

docs/history.rst

@@ -12,6 +12,7 @@ Latest
 - BUG: Make datum name match exact in :func:`pyproj.database.query_utm_crs_info` (pull #887)
 - BUG: Update :class:`pyproj.enums.GeodIntermediateFlag` for future Python compatibility (issue #855)
 - BUG: Hide unnecessary PROJ ERROR from proj_crs_get_coordoperation (issue #873)
+- BUG: Fix pickling for CRS builder classes (issue #897)
 
 3.1.0
 -----

pyproj/crs/crs.py

@@ -6,7 +6,7 @@
 import re
 import threading
 import warnings
-from typing import Any, Callable, Dict, List, Optional, Tuple, Type, Union
+from typing import Any, Callable, Dict, List, Optional, Union
 
 from pyproj._crs import (  # noqa
     _CRS,
@@ -1411,9 +1411,12 @@ def is_geocentric(self) -> bool:
     def __eq__(self, other: Any) -> bool:
         return self.equals(other)
 
-    def __reduce__(self) -> Tuple[Type["CRS"], Tuple[str]]:
-        """special method that allows CRS instance to be pickled"""
-        return self.__class__, (self.srs,)
+    def __getstate__(self) -> Dict[str, str]:
+        return {"srs": self.srs}
+
+    def __setstate__(self, state: Dict[str, Any]):
+        self.__dict__.update(state)
+        self._local = CRSLocal()
 
     def __hash__(self) -> int:
         return hash(self.to_wkt())

test/conftest.py

@@ -1,4 +1,5 @@
 import os
+import pickle
 from contextlib import contextmanager
 from distutils.version import LooseVersion
 from pathlib import Path
@@ -87,3 +88,14 @@ def get_wgs84_datum_name():
     if PROJ_GTE_8:
         return "World Geodetic System 1984 ensemble"
     return "World Geodetic System 1984"
+
+
+def assert_can_pickle(raw_obj, tmp_path):
+    file_path = tmp_path / "temporary.pickle"
+    with open(file_path, "wb") as f:
+        pickle.dump(raw_obj, f)
+
+    with open(file_path, "rb") as f:
+        unpickled = pickle.load(f)
+
+    assert raw_obj == unpickled

test/crs/test_crs.py

@@ -20,6 +20,7 @@
 from test.conftest import (
     HAYFORD_ELLIPSOID_NAME,
     PROJ_GTE_8,
+    assert_can_pickle,
     get_wgs84_datum_name,
     grids_available,
 )
@@ -1475,3 +1476,7 @@ def test_to_3d(crs_input):
 def test_to_3d__name():
     crs_3d = CRS("EPSG:2056").to_3d(name="TEST")
     assert crs_3d.name == "TEST"
+
+
+def test_crs__pickle(tmp_path):
+    assert_can_pickle(CRS("epsg:4326"), tmp_path)

test/crs/test_crs_maker.py

@@ -19,22 +19,24 @@
 from pyproj.crs.coordinate_system import Cartesian2DCS, Ellipsoidal3DCS, VerticalCS
 from pyproj.crs.datum import CustomDatum
 from pyproj.crs.enums import VerticalCSAxis
-from test.conftest import HAYFORD_ELLIPSOID_NAME
+from test.conftest import HAYFORD_ELLIPSOID_NAME, assert_can_pickle
 
 
-def test_make_projected_crs():
+def test_make_projected_crs(tmp_path):
     aeaop = AlbersEqualAreaConversion(0, 0)
     pc = ProjectedCRS(conversion=aeaop, name="Albers")
     assert pc.name == "Albers"
     assert pc.type_name == "Projected CRS"
     assert pc.coordinate_operation == aeaop
+    assert_can_pickle(pc, tmp_path)
 
 
-def test_make_geographic_crs():
+def test_make_geographic_crs(tmp_path):
     gc = GeographicCRS(name="WGS 84")
     assert gc.name == "WGS 84"
     assert gc.type_name == "Geographic 2D CRS"
     assert gc.to_authority() == ("OGC", "CRS84")
+    assert_can_pickle(gc, tmp_path)
 
 
 def test_make_geographic_3d_crs():
@@ -43,15 +45,16 @@ def test_make_geographic_3d_crs():
     assert gcrs.to_authority() == ("IGNF", "WGS84GEODD")
 
 
-def test_make_derived_geographic_crs():
+def test_make_derived_geographic_crs(tmp_path):
     conversion = RotatedLatitudeLongitudeConversion(o_lat_p=0, o_lon_p=0)
     dgc = DerivedGeographicCRS(base_crs=GeographicCRS(), conversion=conversion)
     assert dgc.name == "undefined"
     assert dgc.type_name == "Geographic 2D CRS"
     assert dgc.coordinate_operation == conversion
+    assert_can_pickle(dgc, tmp_path)
 
 
-def test_vertical_crs():
+def test_vertical_crs(tmp_path):
     vc = VerticalCRS(
         name="NAVD88 height",
         datum="North American Vertical Datum 1988",
@@ -61,6 +64,7 @@ def test_vertical_crs():
     assert vc.type_name == "Vertical CRS"
     assert vc.coordinate_system == VerticalCS()
     assert vc.to_json_dict()["geoid_model"]["name"] == "GEOID12B"
+    assert_can_pickle(vc, tmp_path)
 
 
 @pytest.mark.parametrize(
@@ -84,7 +88,7 @@ def test_vertical_crs__chance_cs_axis(axis):
     assert vc.coordinate_system == VerticalCS(axis=axis)
 
 
-def test_compund_crs():
+def test_compund_crs(tmp_path):
     vertcrs = VerticalCRS(
         name="NAVD88 height",
         datum="North American Vertical Datum 1988",
@@ -111,9 +115,10 @@ def test_compund_crs():
     assert compcrs.type_name == "Compound CRS"
     assert compcrs.sub_crs_list[0].type_name == "Projected CRS"
     assert compcrs.sub_crs_list[1].type_name == "Vertical CRS"
+    assert_can_pickle(compcrs, tmp_path)
 
 
-def test_bound_crs():
+def test_bound_crs(tmp_path):
     proj_crs = ProjectedCRS(conversion=UTMConversion(12))
     bound_crs = BoundCRS(
         source_crs=proj_crs,
@@ -126,6 +131,7 @@ def test_bound_crs():
     assert bound_crs.source_crs.coordinate_operation.name == "UTM zone 12N"
     assert bound_crs.coordinate_operation.towgs84 == [1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0]
     assert bound_crs.target_crs.name == "WGS 84"
+    assert_can_pickle(bound_crs, tmp_path)
 
 
 def test_bound_crs__example():