From e1c972ad7f5a5cfe161ced9a223198ddfc1f6019 Mon Sep 17 00:00:00 2001
From: HugoFara <github@hugofara.net>
Date: Sat, 25 Jul 2026 12:57:34 +0200
Subject: [PATCH] DOC: Update fiona CRS compatibility for fiona 1.9+

Fiona 1.9 added `fiona.crs.CRS`, so a dataset's `crs` attribute is now a
CRS object rather than a PROJ string dictionary, and the referenced Fiona
issue asking for a CRS class is resolved. Mirror the structure of the
rasterio section and show passing the CRS objects directly in both
directions, keeping `crs_wkt` as the fallback for older versions.

This also corrects two errors in the existing example, which referenced
the undefined name `dc_crs` and used `WktVersion` without importing it.
---
 docs/crs_compatibility.rst | 36 ++++++++++++++++++++++++------------
 docs/history.rst           |  1 +
 2 files changed, 25 insertions(+), 12 deletions(-)

diff --git a/docs/crs_compatibility.rst b/docs/crs_compatibility.rst
index 74610297a..ec4075d7a 100644
--- a/docs/crs_compatibility.rst
+++ b/docs/crs_compatibility.rst
@@ -112,17 +112,19 @@ fiona
 
 https://github.com/Toblerity/Fiona
 
-Converting from `fiona` CRS to `pyproj.crs.CRS`
+Converting from `fiona.crs.CRS` to `pyproj.crs.CRS`
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-Fiona currently stores the CRS as a PROJ string dictionary in the `crs`
-attribute. As such, it is best to use the `crs_wkt` attribute.
+If you have `fiona >= 1.9`, the CRS of a dataset is a `fiona.crs.CRS`
+that you can pass in directly::
 
-It is also useful to know that plans exist to add CRS class.
-Related GitHub issue `here <https://github.com/Toblerity/Fiona/issues/714>`__.
+    import fiona
+    from pyproj.crs import CRS
 
+    with fiona.open(...) as fds:
+        proj_crs = CRS.from_user_input(fds.crs)
 
-Example::
+Otherwise, you should use the `crs_wkt` attribute::
 
     import fiona
     from pyproj.crs import CRS
@@ -131,27 +133,37 @@ Example::
         proj_crs = CRS.from_wkt(fds.crs_wkt)
 
 
-Converting from `pyproj.crs.CRS` for `fiona`
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+Converting from `pyproj.crs.CRS` to `fiona.crs.CRS`
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 .. warning:: WKT2 is only supported in GDAL 3+
 
+If you have `fiona >= 1.9` and GDAL 3+, then you can pass in the `pyproj.crs.CRS`
+directly::
+
+    import fiona.crs
+    from pyproj.crs import CRS
+
+    proj_crs = CRS.from_epsg(4326)
+    fio_crs = fiona.crs.CRS.from_user_input(proj_crs)
+
 If you want to be compatible across GDAL versions, you can do::
 
     from packaging import version
 
     import fiona
+    import fiona.crs
     from pyproj.crs import CRS
+    from pyproj.enums import WktVersion
 
     proj_crs = CRS.from_epsg(4326)
-
     if version.parse(fiona.__gdal_version__) < version.parse("3.0.0"):
-        fio_crs = proj_crs.to_wkt(WktVersion.WKT1_GDAL)
+        fio_crs = fiona.crs.CRS.from_wkt(proj_crs.to_wkt(WktVersion.WKT1_GDAL))
     else:
         # GDAL 3+ can use WKT2
-        fio_crs = dc_crs.to_wkt()
+        fio_crs = fiona.crs.CRS.from_wkt(proj_crs.to_wkt())
 
-    # with fiona.open(..., "w", crs_wkt=fio_crs) as fds:
+    # with fiona.open(..., "w", crs=fio_crs) as fds:
     #     ...
 
 
diff --git a/docs/history.rst b/docs/history.rst
index 43a43579a..48cb1a023 100644
--- a/docs/history.rst
+++ b/docs/history.rst
@@ -13,6 +13,7 @@ Latest
 - ENH: Added grid_check kwarg to :class:`pyproj.transformer.TransformerGroup` mirroring PROJ CLI ``--grid-check``
 - ENH: Added :class:`pyproj.enums.GridAvailabilityUse` enum for TransformerGroup ``grid_check`` kwarg
 - ENH: Added always_xy kwarg to :meth:`pyproj.transformer.Transformer.from_pipeline`
+- DOC: Update fiona CRS compatibility for fiona 1.9+ (issue #1360)
 - BUG: Clear CONTEXT_THREAD_KEY when destroying PJ_CONTEXT (pull #1541)
 - BUG: Default skew angle for CF grid mapping oblique mercator to 90 (issue #1506)
 - BLD: update build-time dependencies