Make SQLAlchemy optional dependency for vertica Provider (#60177)

* add sqlalchemy as an optional dependency in vertica provider

* add dependency in dev group and fix mypy

Author: Prab-27

providers/vertica/pyproject.toml

@@ -63,6 +63,13 @@ dependencies = [
     "vertica-python>=1.3.0",
 ]
 
+# The optional dependencies should be modified in place in the generated file
+# Any change in the dependencies is preserved when the file is regenerated
+[project.optional-dependencies]
+sqlalchemy = [
+    "sqlalchemy>=1.4.49",
+]
+
 [dependency-groups]
 dev = [
     "apache-airflow",
@@ -71,6 +78,7 @@ dev = [
     "apache-airflow-providers-common-sql",
     # Additional devel dependencies (do not remove this line and add extra development dependencies)
     "apache-airflow-providers-common-sql[pandas,polars]",
+    "apache-airflow-providers-vertica[sqlalchemy]"
 ]
 
 # To build docs:

providers/vertica/src/airflow/providers/vertica/hooks/vertica.py

@@ -17,14 +17,17 @@
 from __future__ import annotations
 
 from collections.abc import Callable, Iterable, Mapping
-from typing import Any, overload
+from typing import TYPE_CHECKING, Any, overload
 
-from sqlalchemy.engine import URL
 from vertica_python import connect
 
+from airflow.exceptions import AirflowOptionalProviderFeatureException
 from airflow.providers.common.sql.hooks.handlers import fetch_all_handler
 from airflow.providers.common.sql.hooks.sql import DbApiHook
 
+if TYPE_CHECKING:
+    from sqlalchemy.engine import URL
+
 
 def vertica_fetch_all_handler(cursor) -> list[tuple] | None:
     """
@@ -137,6 +140,13 @@ def get_conn(self) -> connect:
     @property
     def sqlalchemy_url(self) -> URL:
         """Return a SQLAlchemy URL object with properly formatted query parameters."""
+        try:
+            from sqlalchemy.engine import URL
+        except (ImportError, ModuleNotFoundError) as err:
+            raise AirflowOptionalProviderFeatureException(
+                "The 'sqlalchemy' library is required to use this feature. "
+                "Please install it with: pip install 'apache-airflow-providers-vertica[sqlalchemy]'"
+            ) from err
         conn = self.get_connection(self.get_conn_id())
         extra = conn.extra_dejson or {}