Respect REST endpoint capabilities when checking view existence

pyiceberg/catalog/rest/__init__.py

@@ -1796,6 +1796,14 @@ def view_exists(self, identifier: str | Identifier) -> bool:
         Returns:
             bool: True if the view exists, False otherwise.
         """
+        # fallback in order to work with older rest catalog implementations
+        if Capability.V1_VIEW_EXISTS not in self._supported_endpoints:
+            try:
+                self.load_view(identifier)
+                return True
+            except NoSuchViewError:
+                return False
+
         response = self._session.head(
             self.url(Endpoints.view_exists, prefixed=True, **self._split_identifier_for_path(identifier, IdentifierKind.VIEW)),
         )

tests/catalog/test_rest.py

@@ -945,6 +945,53 @@ def test_view_exists_multilevel_namespace_404(rest_mock: Mocker) -> None:
     assert not catalog.view_exists((multilevel_namespace, view))
 
 
+def test_view_exists_fallback_200(requests_mock: Mocker, example_view_metadata_rest_json: dict[str, Any]) -> None:
+    requests_mock.get(
+        f"{TEST_URI}v1/config",
+        json={"defaults": {}, "overrides": {}, "endpoints": [str(Capability.V1_LOAD_VIEW)]},
+        status_code=200,
+    )
+    requests_mock.get(
+        f"{TEST_URI}v1/namespaces/fokko/views/view",
+        json=example_view_metadata_rest_json,
+        status_code=200,
+        request_headers=TEST_HEADERS,
+    )
+    catalog = RestCatalog("rest", uri=TEST_URI, token=TEST_TOKEN)
+    assert catalog.view_exists(("fokko", "view"))
+
+
+def test_view_exists_fallback_200_legacy_server(requests_mock: Mocker, example_view_metadata_rest_json: dict[str, Any]) -> None:
+    requests_mock.get(
+        f"{TEST_URI}v1/config",
+        json={"defaults": {"view-endpoints-supported": "true"}, "overrides": {}},
+        status_code=200,
+    )
+    requests_mock.get(
+        f"{TEST_URI}v1/namespaces/fokko/views/view",
+        json=example_view_metadata_rest_json,
+        status_code=200,
+        request_headers=TEST_HEADERS,
+    )
+    catalog = RestCatalog("rest", uri=TEST_URI, token=TEST_TOKEN)
+    assert catalog.view_exists(("fokko", "view"))
+
+
+def test_view_exists_fallback_404(requests_mock: Mocker) -> None:
+    requests_mock.get(
+        f"{TEST_URI}v1/config",
+        json={"defaults": {}, "overrides": {}, "endpoints": [str(Capability.V1_LOAD_VIEW)]},
+        status_code=200,
+    )
+    requests_mock.get(
+        f"{TEST_URI}v1/namespaces/fokko/views/view",
+        status_code=404,
+        request_headers=TEST_HEADERS,
+    )
+    catalog = RestCatalog("rest", uri=TEST_URI, token=TEST_TOKEN)
+    assert not catalog.view_exists(("fokko", "view"))
+
+
 def test_list_namespaces_200(rest_mock: Mocker) -> None:
     rest_mock.get(
         f"{TEST_URI}v1/namespaces",