[http-client-python] python support optional path parameter

.chronus/changes/python-optional_path-2025-3-18-10-47-35.md

@@ -0,0 +1,7 @@
+---
+changeKind: feature
+packages:
+  - "@typespec/http-client-python"
+---
+
+Support optional path parameter.

packages/http-client-python/emitter/src/http.ts

@@ -339,8 +339,18 @@ function emitFlattenedParameter(
   };
 }
 
-function emitHttpPathParameter(context: PythonSdkContext, parameter: SdkPathParameter) {
+function emitHttpPathParameter(
+  context: PythonSdkContext,
+  parameter: SdkPathParameter,
+  operation: SdkHttpOperation,
+): Record<string, any> {
   const base = emitParamBase(context, parameter);
+  if (parameter.optional && operation.path.includes(`/{${parameter.serializedName}}`)) {
+    operation.path = operation.path.replace(
+      `/{${parameter.serializedName}}`,
+      `{${parameter.serializedName}}`,
+    );
+  }
   return {
     ...base,
     wireName: parameter.serializedName,
@@ -410,7 +420,7 @@ function emitHttpParameters(
         parameters.push(emitHttpQueryParameter(context, parameter, method));
         break;
       case "path":
-        parameters.push(emitHttpPathParameter(context, parameter));
+        parameters.push(emitHttpPathParameter(context, parameter, operation));
         break;
     }
   }

packages/http-client-python/generator/pygen/codegen/models/parameter.py

@@ -357,6 +357,9 @@ def method_location(  # pylint: disable=too-many-return-statements
         )
         if self.code_model.options["only_path_and_body_params_positional"] and query_or_header:
             return ParameterMethodLocation.KEYWORD_ONLY
+        # for optional path parameter, we need to use keyword only
+        if self.location == ParameterLocation.PATH and self.optional:
+            return ParameterMethodLocation.KEYWORD_ONLY
         return ParameterMethodLocation.POSITIONAL
 
     @classmethod

packages/http-client-python/generator/pygen/codegen/serializers/parameter_serializer.py

@@ -109,6 +109,7 @@ def serialize_parameter(self, parameter: ParameterType, serializer_name: str) ->
             return f"[{serialize_line} if q is not None else '' for q in {origin_name}]"
         return serialize_line
 
+    # pylint: disable=line-too-long
     def serialize_path(
         self,
         parameters: Union[
@@ -124,7 +125,11 @@ def serialize_path(
             [
                 '    "{}": {},'.format(
                     path_parameter.wire_name,
-                    self.serialize_parameter(path_parameter, serializer_name),
+                    (
+                        f'"" if {path_parameter.full_client_name} is None else "/" + {self.serialize_parameter(path_parameter, serializer_name)}'
+                        if path_parameter.optional and isinstance(path_parameter, RequestBuilderParameter)
+                        else self.serialize_parameter(path_parameter, serializer_name)
+                    ),
                 )
                 for path_parameter in parameters
             ]

packages/http-client-python/generator/test/azure/requirements.txt

@@ -38,6 +38,7 @@ azure-mgmt-core==1.3.2
 -e ./generated/encode-numeric
 -e ./generated/parameters-basic
 -e ./generated/parameters-collection-format
+-e ./generated/parameters-path
 -e ./generated/parameters-spread
 -e ./generated/serialization-encoded-name-json
 -e ./generated/server-endpoint-not-defined

packages/http-client-python/generator/test/generic_mock_api_tests/asynctests/test_parameters_path_async.py

@@ -0,0 +1,24 @@
+# -------------------------------------------------------------------------
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# Licensed under the MIT License. See License.txt in the project root for
+# license information.
+# --------------------------------------------------------------------------
+import pytest
+from parameters.path.aio import PathClient
+
+
+@pytest.fixture
+async def client():
+    async with PathClient() as client:
+        yield client
+
+
+@pytest.mark.asyncio
+async def test_normal(client: PathClient):
+    await client.normal("foo")
+
+
+@pytest.mark.asyncio
+async def test_optional(client: PathClient):
+    await client.optional()
+    await client.optional(name="foo")

packages/http-client-python/generator/test/generic_mock_api_tests/asynctests/test_payload_json_merge_patch_async.py

@@ -28,7 +28,7 @@ async def test_create_resource(client: JsonMergePatchClient):
         map={"key": inner_madge},
         array=[inner_madge],
         int_value=1,
-        float_value=1.1,
+        float_value=1.25,
         inner_model=inner_madge,
         int_array=[1, 2, 3],
     )

packages/http-client-python/generator/test/generic_mock_api_tests/test_parameters_path.py

@@ -0,0 +1,22 @@
+# -------------------------------------------------------------------------
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# Licensed under the MIT License. See License.txt in the project root for
+# license information.
+# --------------------------------------------------------------------------
+import pytest
+from parameters.path import PathClient
+
+
+@pytest.fixture
+def client():
+    with PathClient() as client:
+        yield client
+
+
+def test_normal(client: PathClient):
+    client.normal("foo")
+
+
+def test_optional(client: PathClient):
+    client.optional()
+    client.optional(name="foo")

packages/http-client-python/generator/test/generic_mock_api_tests/test_payload_json_merge_patch.py

@@ -27,7 +27,7 @@ def test_create_resource(client: JsonMergePatchClient):
         map={"key": inner_madge},
         array=[inner_madge],
         int_value=1,
-        float_value=1.1,
+        float_value=1.25,
         inner_model=inner_madge,
         int_array=[1, 2, 3],
     )

packages/http-client-python/generator/test/unbranded/requirements.txt

@@ -10,6 +10,7 @@
 -e ./generated/encode-numeric
 -e ./generated/parameters-basic
 -e ./generated/parameters-collection-format
+-e ./generated/parameters-path
 -e ./generated/parameters-spread
 -e ./generated/serialization-encoded-name-json
 -e ./generated/server-endpoint-not-defined

packages/http-client-python/package.json

@@ -58,7 +58,7 @@
     "@azure-tools/typespec-azure-core": ">=0.54.0 <1.0.0",
     "@azure-tools/typespec-azure-resource-manager": ">=0.54.0 <1.0.0",
     "@azure-tools/typespec-azure-rulesets": ">=0.54.0 <1.0.0",
-    "@azure-tools/typespec-client-generator-core": ">=0.54.0 <1.0.0",
+    "@azure-tools/typespec-client-generator-core": ">=0.54.1 <1.0.0",
     "@typespec/compiler": "^1.0.0-0",
     "@typespec/http": "^1.0.0-0",
     "@typespec/openapi": "^1.0.0-0",
@@ -81,7 +81,7 @@
     "@azure-tools/typespec-azure-core": "~0.54.0",
     "@azure-tools/typespec-azure-resource-manager": "~0.54.0",
     "@azure-tools/typespec-azure-rulesets": "~0.54.0",
-    "@azure-tools/typespec-client-generator-core": "~0.54.0",
+    "@azure-tools/typespec-client-generator-core": "~0.54.1",
     "@azure-tools/azure-http-specs": "0.1.0-alpha.13",
     "@typespec/compiler": "^1.0.0-0",
     "@typespec/http": "^1.0.0-0",
@@ -92,7 +92,7 @@
     "@typespec/sse": "~0.68.0",
     "@typespec/streams": "~0.68.0",
     "@typespec/xml": "~0.68.0",
-    "@typespec/http-specs": "0.1.0-alpha.17",
+    "@typespec/http-specs": "0.1.0-alpha.19",
     "@types/js-yaml": "~4.0.5",
     "@types/node": "~22.13.14",
     "@types/semver": "7.5.8",