feat: Add helper function to format query_params for rest transport.

google/api_core/rest_helpers.py

@@ -0,0 +1,76 @@
+# Copyright 2021 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.
+
+"""Helpers for rest transports."""
+
+import itertools
+
+
+def flatten_query_params(obj, key_path=[]):
+    """Flatten a nested dict into a list of (name,value) tuples.
+
+    The result is suitable for setting query params on an http request.
+
+    .. code-block:: python
+
+        >>> obj = {'a':
+        ...         {'b':
+        ...           {'c': ['x', 'y', 'z']} },
+        ...      'd': 'uvw', }
+        >>> flatten_query_params(obj)
+        [('a.b.c', 'x'), ('a.b.c', 'y'), ('a.b.c', 'z'), ('d', 'uvw')]
+
+    Args:
+      obj: a nested dictionary (from json)
+      key_path: a list of name segments, representing levels above this obj.
+
+    Returns: a list of tuples, with each tuple having a (possibly) multi-part name
+      and a scalar value.
+    """
+
+    if obj is None:
+        return []
+    if isinstance(obj, dict):
+        return _flatten_dict(obj, key_path=key_path)
+    if isinstance(obj, list):
+        return _flatten_list(obj, key_path=key_path)
+    return _flatten_value(obj, key_path=key_path)
+
+
+def _is_value(obj):
+    if obj is None:
+        return False
+    return not (isinstance(obj, list) or isinstance(obj, dict))
+
+
+def _flatten_value(obj, key_path=[]):
+    if not key_path:
+        # There must be a key.
+        return []
+    return [('.'.join(key_path), obj)]
+
+
+def _flatten_dict(obj, key_path=[]):
+    return list(
+        itertools.chain(*(flatten_query_params(v, key_path=key_path + [k])
+                        for k, v in obj.items())))
+
+
+def _flatten_list(l, key_path=[]):
+    # Only lists of scalar values are supported.
+    # The name (key_path) is repeated for each value.
+    return list(
+        itertools.chain(*(_flatten_value(elem, key_path=key_path)
+                          for elem in l
+                          if _is_value(elem))))

tests/unit/test_rest_helpers.py

@@ -0,0 +1,61 @@
+# Copyright 2021 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 google.api_core import rest_helpers
+
+
+def test_flatten_none():
+    assert rest_helpers.flatten_query_params(None) == []
+
+
+def test_flatten_empty_dict():
+    assert rest_helpers.flatten_query_params({}) == []
+
+
+def test_flatten_simple_dict():
+    assert rest_helpers.flatten_query_params({'a': 'abc', 'b': 'def'}) == [
+        ('a', 'abc'), ('b', 'def')]
+
+
+def test_flatten_repeated_field():
+    assert rest_helpers.flatten_query_params({'a': ['x', 'y', 'z']}) == [
+        ('a', 'x'), ('a', 'y'), ('a', 'z')]
+
+
+def test_flatten_nested_dict():
+    obj = {'a':
+           {'b':
+            {'c': ['x', 'y', 'z']}},
+           'd':
+           {'e': 'uvw'}}
+    expected_result = [('a.b.c', 'x'),
+                       ('a.b.c', 'y'),
+                       ('a.b.c', 'z'),
+                       ('d.e', 'uvw')]
+
+    assert rest_helpers.flatten_query_params(obj) == expected_result
+
+
+def test_flatten_ignore_repeated_dict():
+    obj = {'a':
+           {'b':
+            {'c':
+             [{'v': 1}, {'v': 2}]
+             }
+            },
+           'd': 'uvw', }
+    # a.b.c is a repeated dict - ignored
+    expected_result = [('d', 'uvw')]
+
+    assert rest_helpers.flatten_query_params(obj) == expected_result