Add view_exists method to REST Catalog (#1242)

Part of the adding view support to the REST catalog: #818 

Todo:
- [x] Add tests
- [x] Add docs

Please let me know what the appropriate place to add docs would be

---------

Co-authored-by: Shiv Gupta <[email protected]>

mkdocs/docs/api.md

@@ -1258,6 +1258,19 @@ with table.manage_snapshots() as ms:
     ms.create_branch(snapshot_id1, "Branch_A").create_tag(snapshot_id2, "tag789")
 ```
 
+## Views
+
+PyIceberg supports view operations.
+
+### Check if a view exists
+
+```python
+from pyiceberg.catalog import load_catalog
+
+catalog = load_catalog("default")
+catalog.view_exists("default.bar")
+```
+
 ## Table Statistics Management
 
 Manage table statistics with operations through the `Table` API:

pyiceberg/catalog/__init__.py

@@ -438,6 +438,17 @@ def table_exists(self, identifier: Union[str, Identifier]) -> bool:
             bool: True if the table exists, False otherwise.
         """
 
+    @abstractmethod
+    def view_exists(self, identifier: Union[str, Identifier]) -> bool:
+        """Check if a view exists.
+
+        Args:
+            identifier (str | Identifier): View identifier.
+
+        Returns:
+            bool: True if the view exists, False otherwise.
+        """
+
     @abstractmethod
     def register_table(self, identifier: Union[str, Identifier], metadata_location: str) -> Table:
         """Register a new table using existing metadata.

pyiceberg/catalog/dynamodb.py

@@ -529,6 +529,9 @@ def list_views(self, namespace: Union[str, Identifier]) -> List[Identifier]:
     def drop_view(self, identifier: Union[str, Identifier]) -> None:
         raise NotImplementedError
 
+    def view_exists(self, identifier: Union[str, Identifier]) -> bool:
+        raise NotImplementedError
+
     def _get_iceberg_table_item(self, database_name: str, table_name: str) -> Dict[str, Any]:
         try:
             return self._get_dynamo_item(identifier=f"{database_name}.{table_name}", namespace=database_name)

pyiceberg/catalog/glue.py

@@ -788,6 +788,9 @@ def list_views(self, namespace: Union[str, Identifier]) -> List[Identifier]:
     def drop_view(self, identifier: Union[str, Identifier]) -> None:
         raise NotImplementedError
 
+    def view_exists(self, identifier: Union[str, Identifier]) -> bool:
+        raise NotImplementedError
+
     @staticmethod
     def __is_iceberg_table(table: TableTypeDef) -> bool:
         return table.get("Parameters", {}).get(TABLE_TYPE, "").lower() == ICEBERG

pyiceberg/catalog/hive.py

@@ -409,6 +409,9 @@ def register_table(self, identifier: Union[str, Identifier], metadata_location:
     def list_views(self, namespace: Union[str, Identifier]) -> List[Identifier]:
         raise NotImplementedError
 
+    def view_exists(self, identifier: Union[str, Identifier]) -> bool:
+        raise NotImplementedError
+
     def _create_lock_request(self, database_name: str, table_name: str) -> LockRequest:
         lock_component: LockComponent = LockComponent(
             level=LockLevel.TABLE, type=LockType.EXCLUSIVE, dbname=database_name, tablename=table_name, isTransactional=True

pyiceberg/catalog/noop.py

@@ -123,5 +123,8 @@ def update_namespace_properties(
     def list_views(self, namespace: Union[str, Identifier]) -> List[Identifier]:
         raise NotImplementedError
 
+    def view_exists(self, identifier: Union[str, Identifier]) -> bool:
+        raise NotImplementedError
+
     def drop_view(self, identifier: Union[str, Identifier]) -> None:
         raise NotImplementedError

pyiceberg/catalog/rest.py

@@ -106,6 +106,7 @@ class Endpoints:
     rename_table: str = "tables/rename"
     list_views: str = "namespaces/{namespace}/views"
     drop_view: str = "namespaces/{namespace}/views/{view}"
+    view_exists: str = "namespaces/{namespace}/views/{view}"
 
 
 class IdentifierKind(Enum):
@@ -906,6 +907,31 @@ def table_exists(self, identifier: Union[str, Identifier]) -> bool:
 
         return False
 
+    @retry(**_RETRY_ARGS)
+    def view_exists(self, identifier: Union[str, Identifier]) -> bool:
+        """Check if a view exists.
+
+        Args:
+            identifier (str | Identifier): View identifier.
+
+        Returns:
+            bool: True if the view exists, False otherwise.
+        """
+        response = self._session.head(
+            self.url(Endpoints.view_exists, prefixed=True, **self._split_identifier_for_path(identifier, IdentifierKind.VIEW)),
+        )
+        if response.status_code == 404:
+            return False
+        elif response.status_code in [200, 204]:
+            return True
+
+        try:
+            response.raise_for_status()
+        except HTTPError as exc:
+            self._handle_non_200_response(exc, {})
+
+        return False
+
     @retry(**_RETRY_ARGS)
     def drop_view(self, identifier: Union[str]) -> None:
         response = self._session.delete(

pyiceberg/catalog/sql.py

@@ -702,5 +702,8 @@ def update_namespace_properties(
     def list_views(self, namespace: Union[str, Identifier]) -> List[Identifier]:
         raise NotImplementedError
 
+    def view_exists(self, identifier: Union[str, Identifier]) -> bool:
+        raise NotImplementedError
+
     def drop_view(self, identifier: Union[str, Identifier]) -> None:
         raise NotImplementedError

tests/catalog/test_base.py

@@ -264,6 +264,9 @@ def list_views(self, namespace: Optional[Union[str, Identifier]] = None) -> List
     def drop_view(self, identifier: Union[str, Identifier]) -> None:
         raise NotImplementedError
 
+    def view_exists(self, identifier: Union[str, Identifier]) -> bool:
+        raise NotImplementedError
+
 
 @pytest.fixture
 def catalog(tmp_path: PosixPath) -> InMemoryCatalog:

tests/catalog/test_rest.py

@@ -492,6 +492,42 @@ def test_list_views_404(rest_mock: Mocker) -> None:
     assert "Namespace does not exist" in str(e.value)
 
 
+def test_view_exists_204(rest_mock: Mocker) -> None:
+    namespace = "examples"
+    view = "some_view"
+    rest_mock.head(
+        f"{TEST_URI}v1/namespaces/{namespace}/views/{view}",
+        status_code=204,
+        request_headers=TEST_HEADERS,
+    )
+    catalog = RestCatalog("rest", uri=TEST_URI, token=TEST_TOKEN)
+    assert catalog.view_exists((namespace, view))
+
+
+def test_view_exists_404(rest_mock: Mocker) -> None:
+    namespace = "examples"
+    view = "some_view"
+    rest_mock.head(
+        f"{TEST_URI}v1/namespaces/{namespace}/views/{view}",
+        status_code=404,
+        request_headers=TEST_HEADERS,
+    )
+    catalog = RestCatalog("rest", uri=TEST_URI, token=TEST_TOKEN)
+    assert not catalog.view_exists((namespace, view))
+
+
+def test_view_exists_multilevel_namespace_404(rest_mock: Mocker) -> None:
+    multilevel_namespace = "core.examples.some_namespace"
+    view = "some_view"
+    rest_mock.head(
+        f"{TEST_URI}v1/namespaces/{multilevel_namespace}/views/{view}",
+        status_code=404,
+        request_headers=TEST_HEADERS,
+    )
+    catalog = RestCatalog("rest", uri=TEST_URI, token=TEST_TOKEN)
+    assert not catalog.view_exists((multilevel_namespace, view))
+
+
 def test_list_namespaces_200(rest_mock: Mocker) -> None:
     rest_mock.get(
         f"{TEST_URI}v1/namespaces",

tests/integration/test_writes/test_writes.py

@@ -1425,6 +1425,23 @@ def test_table_v1_with_null_nested_namespace(session_catalog: Catalog, arrow_tab
     session_catalog.drop_table(identifier)
 
 
+@pytest.mark.integration
+def test_view_exists(
+    spark: SparkSession,
+    session_catalog: Catalog,
+) -> None:
+    identifier = "default.some_view"
+    spark.sql(
+        f"""
+        CREATE VIEW {identifier}
+        AS
+        (SELECT 1 as some_col)
+    """
+    ).collect()
+    assert session_catalog.view_exists(identifier)
+    session_catalog.drop_view(identifier)  # clean up
+
+
 @pytest.mark.integration
 def test_overwrite_all_data_with_filter(session_catalog: Catalog) -> None:
     schema = Schema(