You can import the `APIRouter` class directly from `fastapi`:

```python
from fastapi import APIRouter
```

::: fastapi.APIRouter
    options:
        members:
            - websocket
            - include_router
            - get
            - put
            - post
            - delete
            - options
            - head
            - patch
            - trace

    assert response.json() == {"foo": "baz"}


def test_nested_router():
    app = FastAPI()

    router = APIRouter(prefix="/nested")

    @router.get("/test")
    async def test(var: Annotated[str, Query()] = "bar"):
        return {"foo": var}

    app.include_router(router)

    client = TestClient(app)

    response = client.get("/nested/test")

from fastapi import APIRouter, Body

router = APIRouter()


@router.post("/compute")
def compute(a: int = Body(), b: str = Body()):

    options:
        members:
            - openapi_version
            - webhooks
            - state
            - dependency_overrides
            - openapi
            - websocket
            - include_router
            - get
            - put
            - post
            - delete
            - options
            - head
            - patch
            - trace
            - on_event
            - middleware

        then:
        name == 'org.gradle.SomeClass.Outer.Sibling'
        _ * classMetaData.innerClassNames >> []
        _ * classMetaData.outerClassName >> 'org.gradle.SomeClass.Outer'
        _ * metaDataRepository.get('org.gradle.SomeClass.Outer') >> outerClass
        _ * outerClass.innerClassNames >> ['org.gradle.SomeClass.Outer.Sibling']
    }

    def resolvesUnqualifiedNameToJavaLangPackage() {

)

// adminErasureTestBed - encapsulates subsystems that need to be setup for
// admin-handler unit tests.
type adminErasureTestBed struct {
	erasureDirs []string
	objLayer    ObjectLayer
	router      *mux.Router
	done        context.CancelFunc
}

// prepareAdminErasureTestBed - helper function that setups a single-node
// Erasure backend for admin-handler tests.

```Python hl_lines="35"
{!../../../docs_src/openapi_callbacks/tutorial001.py!}
```

!!! tip "Tipp"
    Beachten Sie, dass Sie nicht den Router selbst (`invoices_callback_router`) an `callback=` übergeben, sondern das Attribut `.routes`, wie in `invoices_callback_router.routes`.

### Es in der Dokumentation ansehen

class CustomModel(BaseModel):
    a: int


app = FastAPI()

callback_router = APIRouter(default_response_class=JSONResponse)


@callback_router.get(
    "{$callback_url}/callback/", responses={400: {"model": CustomModel}}
)
def callback_route():
    pass  # pragma: no cover


@app.post("/", callbacks=callback_router.routes)
def main_route(callback_url: HttpUrl):
    pass  # pragma: no cover

              ]
             }
            ]
           },
           "http_filters": [
            {
             "name": "envoy.filters.http.router",
             "typed_config": {
              "@type": "type.googleapis.com/envoy.extensions.filters.http.router.v3.Router"
             }
            }
           ]
          }
         }
        ]
       }
      ]
     },

	"testing"

	"github.com/minio/mux"
)

// Test cross domain xml handler.
func TestCrossXMLHandler(t *testing.T) {
	// Server initialization.
	router := mux.NewRouter().SkipClean(true).UseEncodedPath()
	handler := setCrossDomainPolicyMiddleware(router)
	srv := httptest.NewServer(handler)

	resp, err := http.Get(srv.URL + crossDomainXMLEntity)
	if err != nil {
		t.Fatal(err)
	}