From 4e18031dcd75766b7a5dcc83e3658bff5f3ad1c1 Mon Sep 17 00:00:00 2001
From: Stefan Binder <binder_stefan@outlook.com>
Date: Fri, 27 Jan 2023 22:44:21 +0100
Subject: [PATCH] Fix incompatibility with jsonschema < 4.5 (#2860)

* Fix incompatibility with jsonschema < 4.17

* Add changelog entry for 4.2.2

* Fix jsonschema version in changelog
---
 altair/utils/schemapi.py   | 7 ++++---
 doc/releases/changes.rst   | 7 +++++++
 tools/schemapi/schemapi.py | 7 ++++---
 3 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/altair/utils/schemapi.py b/altair/utils/schemapi.py
index f170acd3f..d3e1aef82 100644
--- a/altair/utils/schemapi.py
+++ b/altair/utils/schemapi.py
@@ -50,9 +50,10 @@ def validate_jsonschema(spec, schema, resolver=None):
     # e.g. '#/definitions/ValueDefWithCondition<MarkPropFieldOrDatumDef,
     # (Gradient|string|null)>' would be a valid $ref in a Vega-Lite schema but
     # it is not a valid URI reference due to the characters such as '<'.
-    validator = JSONSCHEMA_VALIDATOR(
-        schema, format_checker=JSONSCHEMA_VALIDATOR.FORMAT_CHECKER, resolver=resolver
-    )
+    validator_kwargs = {"resolver": resolver}
+    if hasattr(JSONSCHEMA_VALIDATOR, "FORMAT_CHECKER"):
+        validator_kwargs["format_checker"] = JSONSCHEMA_VALIDATOR.FORMAT_CHECKER
+    validator = JSONSCHEMA_VALIDATOR(schema, **validator_kwargs)
     error = jsonschema.exceptions.best_match(validator.iter_errors(spec))
     if error is not None:
         raise error
diff --git a/doc/releases/changes.rst b/doc/releases/changes.rst
index bdcf44b31..a2598b2b3 100644
--- a/doc/releases/changes.rst
+++ b/doc/releases/changes.rst
@@ -3,6 +3,13 @@
 Altair Change Log
 =================
 
+Version 4.2.2 (released XXX YY, 2023)
+-------------------------------------
+
+Bug Fixes
+~~~~~~~~~
+- Fix incompatibility with jsonschema < 4.5 which got introduced in Altair 4.2.1 (#2860).
+
 Version 4.2.1 (released Jan 26, 2023)
 -------------------------------------
 
diff --git a/tools/schemapi/schemapi.py b/tools/schemapi/schemapi.py
index 3844483a7..4949ba7f8 100644
--- a/tools/schemapi/schemapi.py
+++ b/tools/schemapi/schemapi.py
@@ -48,9 +48,10 @@ def validate_jsonschema(spec, schema, resolver=None):
     # e.g. '#/definitions/ValueDefWithCondition<MarkPropFieldOrDatumDef,
     # (Gradient|string|null)>' would be a valid $ref in a Vega-Lite schema but
     # it is not a valid URI reference due to the characters such as '<'.
-    validator = JSONSCHEMA_VALIDATOR(
-        schema, format_checker=JSONSCHEMA_VALIDATOR.FORMAT_CHECKER, resolver=resolver
-    )
+    validator_kwargs = {"resolver": resolver}
+    if hasattr(JSONSCHEMA_VALIDATOR, "FORMAT_CHECKER"):
+        validator_kwargs["format_checker"] = JSONSCHEMA_VALIDATOR.FORMAT_CHECKER
+    validator = JSONSCHEMA_VALIDATOR(schema, **validator_kwargs)
     error = jsonschema.exceptions.best_match(validator.iter_errors(spec))
     if error is not None:
         raise error