Added routers nesting.

Signed-off-by: Pavel Kirilin <win10@list.ru>

Author: s3rius

README.md

@@ -52,6 +52,20 @@ web.run_app(app)
 
 ```
 
+Also, you can nest routers with prefixes,
+
+```python
+api_router = Router()
+
+memes_router = Router()
+
+main_router = Router()
+
+main_router.add_routes(api_router, prefix="/api")
+main_router.add_routes(memes_router, prefix="/memes")
+```
+
+
 ## Default dependencies
 
 By default this library provides only two injectables. `web.Request` and `web.Application`.

aiohttp_deps/router.py

@@ -1,3 +1,5 @@
+from typing import Iterable
+
 from aiohttp import web
 
 
@@ -13,3 +15,25 @@ class Router(web.RouteTableDef):
 
     New types are introduced in stub file: router.pyi.
     """
+
+    def add_routes(self, router: Iterable[web.RouteDef], prefix: str = "") -> None:
+        """
+        Append another router's routes to this one.
+
+        :param router: router to get routes from.
+        :param prefix: url prefix for routes, defaults to ""
+        :raises ValueError: if prefix is incorrect.
+        """
+        if prefix and not prefix.startswith("/"):
+            raise ValueError("Prefix must start with a `/`")
+        if prefix and prefix.endswith("/"):
+            raise ValueError("Prefix should not end with a `/`")
+        for route in router:
+            self._items.append(
+                web.RouteDef(
+                    method=route.method,
+                    path=prefix + route.path,
+                    handler=route.handler,
+                    kwargs=route.kwargs,
+                ),
+            )

aiohttp_deps/router.pyi

@@ -1,4 +1,4 @@
-from typing import Any, Awaitable, Callable, Type, Union
+from typing import Any, Awaitable, Callable, Iterable, Type, Union
 
 from aiohttp import web
 from aiohttp.abc import AbstractView
@@ -18,3 +18,4 @@ class Router(web.RouteTableDef):
     def delete(self, path: str, **kwargs: Any) -> _Deco: ...
     def options(self, path: str, **kwargs: Any) -> _Deco: ...
     def view(self, path: str, **kwargs: Any) -> _Deco: ...
+    def add_routes(self, router: Iterable[web.RouteDef], prefix: str = "") -> None: ...

tests/test_router.py

@@ -0,0 +1,113 @@
+import pytest
+from aiohttp import web
+
+from aiohttp_deps import Router
+from tests.conftest import ClientGenerator
+
+
+@pytest.mark.anyio
+async def test_router_add_routes(
+    my_app: web.Application,
+    aiohttp_client: ClientGenerator,
+):
+    api_router = Router()
+
+    @api_router.get("/a")
+    async def _():
+        return web.json_response({"a": "b"})
+
+    @api_router.get("/b")
+    async def _():
+        return web.json_response({"b": "c"})
+
+    router = Router()
+    router.add_routes(api_router)
+
+    my_app.router.add_routes(router)
+
+    client = await aiohttp_client(my_app)
+    response = await client.get("/a")
+    assert response.status == 200
+    assert await response.json() == {"a": "b"}
+
+    response = await client.get("/b")
+    assert response.status == 200
+    assert await response.json() == {"b": "c"}
+
+
+@pytest.mark.anyio
+async def test_prefixed_routes(
+    my_app: web.Application,
+    aiohttp_client: ClientGenerator,
+):
+    api_router = Router()
+
+    @api_router.get("/a")
+    async def _():
+        return web.json_response({"a": "b"})
+
+    router = Router()
+    router.add_routes(api_router, prefix="/api")
+
+    my_app.router.add_routes(router)
+
+    client = await aiohttp_client(my_app)
+    response = await client.get("/api/a")
+    assert response.status == 200
+    assert await response.json() == {"a": "b"}
+
+
+@pytest.mark.anyio
+async def test_deep_nesting(
+    my_app: web.Application,
+    aiohttp_client: ClientGenerator,
+):
+    last_router = Router()
+
+    @last_router.get("/a")
+    async def _():
+        return web.json_response({"a": "b"})
+
+    # Generate 20 nested routers.
+    for i in range(20):
+        new_router = Router()
+        new_router.add_routes(last_router, prefix=f"/{i}")
+        last_router = new_router
+
+    router = Router()
+    router.add_routes(last_router, prefix="/api")
+
+    my_app.router.add_routes(router)
+
+    client = await aiohttp_client(my_app)
+    url = "/api/" + "/".join([str(i) for i in range(20)][::-1]) + "/a"
+    print(url)
+    response = await client.get(url)
+    assert response.status == 200
+    assert await response.json() == {"a": "b"}
+
+
+@pytest.mark.anyio
+async def test_prefixed_routes_no_start_slash():
+    api_router = Router()
+
+    @api_router.get("/a")
+    async def _():
+        """Nothing."""
+
+    router = Router()
+    with pytest.raises(ValueError):
+        router.add_routes(api_router, prefix="api")
+
+
+@pytest.mark.anyio
+async def test_prefixed_routes_trailing_slash():
+    api_router = Router()
+
+    @api_router.get("/a")
+    async def _():
+        """Nothing."""
+
+    router = Router()
+    with pytest.raises(ValueError):
+        router.add_routes(api_router, prefix="/api/")