feat: microgen - adds _helpers.py.j2 template

scripts/microgenerator/templates/_helpers.py.j2

@@ -0,0 +1,95 @@
+# -*- coding: utf-8 -*-
+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+from typing import Any, Dict, List, Optional, Type
+
+
+def _create_request(
+    request_class: Type,
+    path_identifier: str,
+    expected_args: List[str],
+    default_project_id: Optional[str] = None,
+) -> Any:
+    """
+    Constructs a *Request object from a class, path_identifier, and expected args.
+
+    Args:
+        request_class: The class of the request object to create (e.g., GetDatasetRequest).
+        path_identifier: The dot-separated string of resource IDs.
+        expected_args: An ordered list of the argument names the request object
+                       expects (e.g., ['project_id', 'dataset_id', 'table_id']).
+        default_project_id: The default project ID to use if needed.
+
+    Returns:
+        An instantiated request object.
+
+    Examples:
+        >>> # Example with project_id provided in path_identifier
+        >>> request = _create_request(
+        ...     request_class=GetDatasetRequest,
+        ...     path_identifier="my-project.my-dataset",
+        ...     expected_args=["project_id", "dataset_id"]
+        ... )
+        >>> request.project_id
+        'my-project'
+        >>> request.dataset_id
+        'my-dataset'
+
+        >>> # Example with project_id omitted from path_identifier, using default_project_id
+        >>> request = _create_request(
+        ...     request_class=GetDatasetRequest,
+        ...     path_identifier="my-dataset",
+        ...     expected_args=["project_id", "dataset_id"],
+        ...     default_project_id="my-default-project"
+        ... )
+        >>> request.project_id
+        'my-default-project'
+        >>> request.dataset_id
+        'my-dataset'
+
+    """
+    # Start of inlined parse_path_to_request_inputs
+    segments = path_identifier.split(".")
+    num_segments = len(segments)
+    num_expected = len(expected_args)
+    project_id_is_expected = "project_id" in expected_args
+
+    # Validate the number of segments.
+    if not (
+        num_segments == num_expected
+        or (project_id_is_expected and num_segments == num_expected - 1)
+    ):
+        raise ValueError(
+            f"Invalid path identifier '{path_identifier}'. Expected "
+            f"{num_expected} parts (or {num_expected - 1} if project_id is "
+            f"omitted), but got {num_segments}."
+        )
+
+    # If project_id is implicitly expected, use the default.
+    if project_id_is_expected and num_segments == num_expected - 1:
+        if not default_project_id:
+            raise ValueError(
+                f"Missing project_id in path '{path_identifier}' and no "
+                "default_project_id was provided."
+            )
+        # Prepend the default project_id to the segments.
+        segments.insert(0, default_project_id)
+
+    request_inputs = dict(zip(expected_args, segments))
+    # End of inlined parse_path_to_request_inputs
+
+    # Instantiate the request object.
+    return request_class(**request_inputs)