pdyap version dependent client.open_url call (#6656)

Co-authored-by: Deepak Cherian <[email protected]>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

doc/whats-new.rst

@@ -34,6 +34,8 @@ Bug fixes
   allowing the ``encoding`` and ``unlimited_dims`` options with ``save_mfdataset``.
   (:issue:`6684`)
   By `Travis A. O'Brien <https://github.com/taobrienlbl>`_.
+- Fix backend support of pydap versions <3.3.0  (:issue:`6648`, :pull:`6656`).
+  By `Hauke Schulz <https://github.com/observingClouds>`_.
 - :py:meth:`Dataset.where` with ``drop=True`` now behaves correctly with mixed dimensions.
   (:issue:`6227`, :pull:`6690`)
   By `Michael Niklas <https://github.com/headtr1ck>`_.

xarray/backends/pydap_.py

@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 import numpy as np
+from packaging.version import Version
 
 from ..core import indexing
 from ..core.pycompat import integer_types
@@ -17,7 +18,9 @@
 
 try:
     import pydap.client
+    import pydap.lib
 
+    pydap_version = pydap.lib.__version__
     has_pydap = True
 except ModuleNotFoundError:
     has_pydap = False
@@ -99,29 +102,24 @@ def open(
         user_charset=None,
     ):
 
-        if output_grid is None:
-            output_grid = True
-
-        if verify is None:
-            verify = True
-
         if timeout is None:
             from pydap.lib import DEFAULT_TIMEOUT
 
             timeout = DEFAULT_TIMEOUT
 
-        if user_charset is None:
-            user_charset = "ascii"
-
-        ds = pydap.client.open_url(
-            url=url,
-            application=application,
-            session=session,
-            output_grid=output_grid,
-            timeout=timeout,
-            verify=verify,
-            user_charset=user_charset,
-        )
+        kwargs = {
+            "url": url,
+            "application": application,
+            "session": session,
+            "output_grid": output_grid or True,
+            "timeout": timeout,
+        }
+        if Version(pydap_version) >= Version("3.3.0"):
+            if verify is not None:
+                kwargs.update({"verify": verify})
+            if user_charset is not None:
+                kwargs.update({"user_charset": user_charset})
+        ds = pydap.client.open_url(**kwargs)
         return cls(ds)
 
     def open_store_variable(self, var):