And it also includes a default exception handler for it.

To override it, import the `RequestValidationError` and use it with `@app.exception_handler(RequestValidationError)` to decorate the exception handler.

The exception handler will receive a `Request` and the exception.

```Python hl_lines="2  14-16"
{!../../../docs_src/handling_errors/tutorial004.py!}
```

			t.Fatalf("Test %d: Failed to create HTTP request for GetBucketPolicyHandler: <ERROR> %v", i+1, err)
		}
		// Since `apiRouter` satisfies `http.Handler` it has a ServeHTTP to execute the logic of the handler.
		// Call the ServeHTTP to execute the handler, GetBucketPolicyHandler handles the request.
		apiRouter.ServeHTTP(recV4, reqV4)
		// Assert the response code with the expected status.
		if recV4.Code != testCase.expectedRespStatus {

	for _, val := range v {
		s = append(s, fmt.Sprintf("%v", val))
	}
	err := fmt.Errorf("metrics handler error: %v", strings.Join(s, " "))
	metricsLogIf(GlobalContext, err)
}

type metricsV3Server struct {
	registry *prometheus.Registry
	opts     promhttp.HandlerOpts
	authFn   func(http.Handler) http.Handler

	metricsData *metricsV3Collection
}

			t.Fatalf("Test %d: %s: Failed to create HTTP request for Head Object: <ERROR> %v", i+1, instanceType, err)
		}
		// Since `apiRouter` satisfies `http.Handler` it has a ServeHTTP to execute the logic of the handler.
		// Call the ServeHTTP to execute the handler,`func (api objectAPIHandlers) GetObjectHandler`  handles the request.
		apiRouter.ServeHTTP(rec, req)

		// Assert the response code with the expected status.

{!../../../docs_src/events/tutorial001.py!}
```

In this case, the `startup` event handler function will initialize the items "database" (just a `dict`) with some values.

You can add more than one event handler function.

And your application won't start receiving requests until all the `startup` event handlers have completed.

### `shutdown` event

// 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.

package handlers

import (
	"context"
	"errors"
	"fmt"
	"sort"
	"strings"
	"time"

	corev1 "k8s.io/api/core/v1"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/labels"

  TFE_TensorHandle* var_handle0 = TestVariable(ctx, 1.0, dev0_name);
  EXPECT_NE(var_handle0, nullptr);
  TFE_TensorHandle* var_handle1 = TestVariable(ctx, 2.0, dev1_name);
  EXPECT_NE(var_handle1, nullptr);

  TFE_TensorHandle* value_handle = nullptr;
  ReadVariable(ctx, var_handle1, &value_handle);
  CheckTFE_TensorHandleHasFloats(value_handle, {2});
  TFE_DeleteTensorHandle(value_handle);

import java.net.URLConnection;
import java.net.URLStreamHandler;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.io.PrintStream;

public class Handler extends URLStreamHandler {

    static final URLStreamHandler SMB_HANDLER = new Handler();

    protected int getDefaultPort() {
        return SmbConstants.DEFAULT_PORT;
    }
    public URLConnection openConnection( URL u ) throws IOException {

func (m *Manager) AddToMux(router *mux.Router) {
	router.Handle(RoutePath, m.Handler())
}

// Handler returns a handler that can be used to serve grid requests.
// This should be connected on RoutePath to the main server.
func (m *Manager) Handler() http.HandlerFunc {
	return func(w http.ResponseWriter, req *http.Request) {
		defer func() {
			if debugPrint {
				fmt.Printf("grid: Handler returning from: %v %v\n", req.Method, req.URL)
			}

app = FastAPI(
    exception_handlers={
        HTTPException: http_exception_handler,
        RequestValidationError: request_validation_exception_handler,
        Exception: server_error_exception_handler,
    }
)

client = TestClient(app)


@app.get("/http-exception")
def route_with_http_exception():
    raise HTTPException(status_code=400)


@app.get("/request-validation/{param}/")