Raise exception when attempting to write schema not supported by driver

fiona/collection.py

@@ -11,7 +11,7 @@
 from fiona.ogrext import (
     calc_gdal_version_num, get_gdal_version_num, get_gdal_release_name)
 from fiona.ogrext import buffer_to_virtual_file, remove_virtual_file, GEOMETRY_TYPES
-from fiona.errors import DriverError, SchemaError, CRSError, UnsupportedGeometryTypeError
+from fiona.errors import (DriverError, SchemaError, CRSError, UnsupportedGeometryTypeError, DriverSupportError)
 from fiona._drivers import driver_count, GDALEnv
 from fiona.drvsupport import supported_drivers, AWSGDALEnv
 from six import string_types, binary_type
@@ -133,6 +133,8 @@ def __init__(self, path, mode='r', driver=None, schema=None, crs=None,
                 raise SchemaError("schema lacks: geometry")
             self._schema = schema
 
+            self._check_schema_driver_support()
+
             if crs_wkt:
                 self._crs_wkt = crs_wkt
             elif crs:
@@ -395,6 +397,31 @@ def bounds(self):
             self._bounds = self.session.get_extent()
         return self._bounds
 
+    def _check_schema_driver_support(self):
+        """Check support for the schema against the driver
+
+        See GH#572 for discussion.
+        """
+        gdal_version_major = get_gdal_version_num() // 1000000
+        for field in self._schema["properties"]:
+            field_type = field.split(":")[0]
+            if self._driver == "ESRI Shapefile":
+                if field_type == "datetime":
+                    raise DriverSupportError("ESRI Shapefile does not support datetime fields")
+                elif field_type == "time":
+                    raise DriverSupportError("ESRI Shapefile does not support time fields")
+            elif self._driver == "GPKG":
+                if field_type == "time":
+                    raise DriverSupportError("GPKG does not support time fields")
+            elif self._driver == "GeoJSON":
+                if gdal_version_major == 1:
+                    if field_type == "date":
+                        warnings.warn("GeoJSON driver in GDAL 1.x silently converts date to string in non-standard format")
+                    elif field_type == "datetime":
+                        warnings.warn("GeoJSON driver in GDAL 1.x silently converts datetime to string in non-standard format")
+                    elif field_type == "time":
+                        warnings.warn("GeoJSON driver in GDAL 1.x silently converts time to string")
+
     def flush(self):
         """Flush the buffer."""
         if self.session is not None:

fiona/errors.py

@@ -25,6 +25,10 @@ class DriverIOError(IOError):
     """A format specific driver error."""
 
 
+class DriverSupportError(DriverIOError):
+    """Driver does not support schema"""
+
+
 class DatasetDeleteError(IOError):
     """Failure to delete a dataset"""
 

tests/test_datetime.py

@@ -6,6 +6,7 @@
 import pytest
 import tempfile, shutil
 import os
+from fiona.errors import DriverSupportError
 from .conftest import requires_gpkg
 
 GDAL_MAJOR_VER = fiona.get_gdal_version_num() // 1000000
@@ -139,11 +140,13 @@ def write_data(self, driver):
     def test_shapefile(self):
         # datetime is silently converted to date
         driver = "ESRI Shapefile"
-        schema, features = self.write_data(driver)
+
+        with pytest.raises(DriverSupportError):
+            schema, features = self.write_data(driver)
 
-        assert schema["properties"]["datetime"] == "date"
-        assert features[0]["properties"]["datetime"] == "2018-03-25"
-        assert features[1]["properties"]["datetime"] is None
+        # assert schema["properties"]["datetime"] == "date"
+        # assert features[0]["properties"]["datetime"] == "2018-03-25"
+        # assert features[1]["properties"]["datetime"] is None
 
     @requires_gpkg
     def test_gpkg(self):
@@ -219,25 +222,26 @@ def write_data(self, driver):
         return schema, features
 
     def test_shapefile(self):
-        # attempting to write time field to shapefile raises KeyError
-        # this is a bug in fiona
+        # no support for time fields
         driver = "ESRI Shapefile"
-        with pytest.raises(KeyError):
+        with pytest.raises(DriverSupportError):
             self.write_data(driver)
 
     @requires_gpkg
     def test_gpkg(self):
         # GDAL 2: time field is silently converted to string
         # GDAL 1: time field dropped completely
         driver = "GPKG"
-        schema, features = self.write_data(driver)
+
+        with pytest.raises(DriverSupportError):
+            schema, features = self.write_data(driver)
 
-        if GDAL_MAJOR_VER >= 2:
-            assert schema["properties"]["time"] == "str"
-            assert features[0]["properties"]["time"] == TIME_EXAMPLE
-            assert features[1]["properties"]["time"] is None
-        else:
-            assert "time" not in schema["properties"]
+        # if GDAL_MAJOR_VER >= 2:
+        #     assert schema["properties"]["time"] == "str"
+        #     assert features[0]["properties"]["time"] == TIME_EXAMPLE
+        #     assert features[1]["properties"]["time"] is None
+        # else:
+        #     assert "time" not in schema["properties"]
 
     def test_geojson(self):
         # GDAL 1: time field silently converted to string