ENH: improve support for datetime columns

CHANGES.md

@@ -1,5 +1,12 @@
 # CHANGELOG
 
+## 0.12.0 (????-??-??)
+
+### Improvements
+
+-   Add `datetimes` parameter to `read_dataframe` to choose the way datetime columns are
+    returned + several fixes when reading and writing datetimes (#486).
+
 ## 0.11.1 (2025-08-02)
 
 ### Bug fixes

pyogrio/_io.pyx

@@ -936,10 +936,16 @@ cdef process_fields(
 
             if datetime_as_string:
                 # defer datetime parsing to user/ pandas layer
-                # Update to OGR_F_GetFieldAsISO8601DateTime when GDAL 3.7+ only
-                data[i] = get_string(
-                    OGR_F_GetFieldAsString(ogr_feature, field_index), encoding=encoding
-                )
+                IF CTE_GDAL_VERSION >= (3, 7, 0):
+                    data[i] = get_string(
+                        OGR_F_GetFieldAsISO8601DateTime(ogr_feature, field_index, NULL),
+                        encoding=encoding,
+                    )
+                ELSE:
+                    data[i] = get_string(
+                        OGR_F_GetFieldAsString(ogr_feature, field_index),
+                        encoding=encoding,
+                    )
             else:
                 success = OGR_F_GetFieldAsDateTimeEx(
                     ogr_feature,
@@ -1502,6 +1508,7 @@ def ogr_open_arrow(
     int return_fids=False,
     int batch_size=0,
     use_pyarrow=False,
+    datetime_as_string=False,
 ):
 
     cdef int err = 0
@@ -1722,6 +1729,12 @@ def ogr_open_arrow(
                 "GEOARROW".encode("UTF-8")
             )
 
+        # Read DateTime fields as strings, as the Arrow DateTime column type is
+        # quite limited regarding support for mixed timezones,...
+        IF CTE_GDAL_VERSION >= (3, 11, 0):
+            if datetime_as_string:
+                options = CSLSetNameValue(options, "DATETIME_AS_STRING", "YES")
+
         # make sure layer is read from beginning
         OGR_L_ResetReading(ogr_layer)
 
@@ -1749,6 +1762,7 @@ def ogr_open_arrow(
             "crs": crs,
             "encoding": encoding,
             "fields": fields[:, 2],
+            "dtypes": fields[:, 3],
             "geometry_type": geometry_type,
             "geometry_name": geometry_name,
             "fid_column": fid_column,

pyogrio/_ogr.pxd

@@ -415,6 +415,14 @@ IF CTE_GDAL_VERSION >= (3, 6, 0):
         )
 
 
+IF CTE_GDAL_VERSION >= (3, 7, 0):
+
+    cdef extern from "ogr_api.h":
+        const char* OGR_F_GetFieldAsISO8601DateTime(
+            OGRFeatureH feature, int n, char** papszOptions
+        )
+
+
 IF CTE_GDAL_VERSION >= (3, 8, 0):
 
     cdef extern from "ogr_api.h":