Add a command line tool to generate OAS in a file

aiohttp_pydantic/oas/__main__.py

@@ -0,0 +1,8 @@
+import argparse
+
+from .cmd import setup
+
+parser = argparse.ArgumentParser(description="Generate Open API Specification")
+setup(parser)
+args = parser.parse_args()
+args.func(args)

aiohttp_pydantic/oas/cmd.py

@@ -0,0 +1,45 @@
+import argparse
+import importlib
+import json
+
+from .view import generate_oas
+
+
+def application_type(value):
+    """
+    Return aiohttp application defined in the value.
+    """
+    try:
+        module_name, app_name = value.split(":")
+    except ValueError:
+        module_name, app_name = value, "app"
+
+    module = importlib.import_module(module_name)
+    try:
+        if app_name.endswith("()"):
+            app_name = app_name.strip("()")
+            factory_app = getattr(module, app_name)
+            return factory_app()
+        return getattr(module, app_name)
+
+    except AttributeError as error:
+        raise argparse.ArgumentTypeError(error) from error
+
+
+def setup(parser: argparse.ArgumentParser):
+    parser.add_argument(
+        "apps",
+        metavar="APP",
+        type=application_type,
+        nargs="*",
+        help="The name of the module containing the asyncio.web.Application."
+        " By default the variable named 'app' is loaded but you can define"
+        " an other variable name ending the name of module with : characters"
+        " and the name of variable. Example: my_package.my_module:my_app",
+    )
+
+    parser.set_defaults(func=show_oas)
+
+
+def show_oas(args: argparse.Namespace):
+    print(json.dumps(generate_oas(args.apps), sort_keys=True, indent=4))

aiohttp_pydantic/oas/view.py

@@ -1,7 +1,8 @@
 import typing
-from typing import Type
+from typing import List, Type
 
 from aiohttp.web import Response, json_response
+from aiohttp.web_app import Application
 from pydantic import BaseModel
 
 from aiohttp_pydantic.oas.struct import OpenApiSpec3, OperationObject, PathItem
@@ -106,11 +107,10 @@ def _add_http_method_to_oas(
         _OASResponseBuilder(oas_operation).build(return_type)
 
 
-async def get_oas(request):
+def generate_oas(apps: List[Application]) -> dict:
     """
-    Generate Open Api Specification from PydanticView in application.
+    Generate and return Open Api Specification from PydanticView in application.
     """
-    apps = request.app["apps to expose"]
     oas = OpenApiSpec3()
     for app in apps:
         for resources in app.router.resources():
@@ -125,7 +125,15 @@ async def get_oas(request):
                     else:
                         _add_http_method_to_oas(path, resource_route.method, view)
 
-    return json_response(oas.spec)
+    return oas.spec
+
+
+async def get_oas(request):
+    """
+    View to generate the Open Api Specification from PydanticView in application.
+    """
+    apps = request.app["apps to expose"]
+    return json_response(generate_oas(apps))
 
 
 async def oas_ui(request):