### Rewriting Requests

Interceptors can add, remove, or replace request headers. They can also transform the body of those requests that have one. For example, you can use an application interceptor to add request body compression if you're connecting to a webserver known to support it.

```java
/** This interceptor compresses the HTTP request body. Many webservers can't handle this! */
final class GzipRequestInterceptor implements Interceptor {

	// Corrupted XML
	malformedReq := &http.Request{
		Body:          io.NopCloser(bytes.NewReader([]byte("<>"))),
		ContentLength: int64(len("<>")),
	}

	// Not an XML
	badRequest := &http.Request{
		Body:          io.NopCloser(bytes.NewReader([]byte("garbage"))),
		ContentLength: int64(len("garbage")),
	}

	// generates the input request with XML bucket configuration set to the request body.

    handshakeServerNames = socket.handshakeServerNames,
    method = requestLine.method,
    target = requestLine.target,
    version = requestLine.version,
    url = requestUrl,
    headers = headers,
    body = body,
    bodySize = bodySize,
    chunkSizes = chunkSizes,
    failure = failure,
  )
}

internal fun decodeRequestLine(requestLine: String?): RequestLine {
  val parts =
    when {

    assert response.json() == {
        "detail": [
            {
                "type": "missing",
                "loc": ["body", "name"],
                "msg": "Field required",
                "input": {},
            },
            {
                "type": "missing",
                "loc": ["body", "price"],
                "msg": "Field required",
                "input": {},
            },
        ]
    }

  private fun uppercaseResponse(response: Response): Response {
    val uppercaseBody: ResponseBody =
      object : ForwardingResponseBody(response.body) {
        override fun source(): BufferedSource = uppercaseSource(delegate().source()).buffer()
      }
    return response
      .newBuilder()
      .body(uppercaseBody)
      .build()
  }

  private fun uppercaseSource(source: BufferedSource): ForwardingSource {

@app.put("/invalid-user/{user_id}")
def put_invalid_user(
    user_id: str, name: str = Body(), db: dict = Depends(get_database)
):
    db[user_id] = name
    raise HTTPException(status_code=400, detail="Invalid user")


@app.put("/user/{user_id}")
def put_user(user_id: str, name: str = Body(), db: dict = Depends(get_database)):
    db[user_id] = name
    return {"message": "OK"}

	tw := tar.NewWriter(&buf)
	var files = []struct {
		Name, Body string
	}{
		{"readme.txt", "This archive contains some text files."},
		{"gopher.txt", "Gopher names:\nGeorge\nGeoffrey\nGonzo"},
		{"todo.txt", "Get animal handling license."},
	}
	for _, file := range files {
		hdr := &tar.Header{
			Name: file.Name,
			Mode: 0600,
			Size: int64(len(file.Body)),
		}
		if err := tw.WriteHeader(hdr); err != nil {

    assert response.json() == {
        "detail": [
            {
                "type": "missing",
                "loc": ["body", "item"],
                "msg": "Field required",
                "input": None,
            },
            {
                "type": "missing",
                "loc": ["body", "user"],
                "msg": "Field required",
                "input": None,
            },
            {

      client.newCall(requestWithUpgrade).execute()
    }
  }

  @Test
  fun upgradesOnReusedConnection() {
    server.enqueue(MockResponse(body = "normal request"))
    client.newCall(Request(server.url("/"))).execute().use { response ->
      assertThat(response.body.string()).isEqualTo("normal request")
    }

    upgrade()

    assertThat(server.takeRequest().connectionIndex).isEqualTo(0)

@invoices_callback_router.post(
    "{$callback_url}/invoices/{$request.body.id}", response_model=InvoiceEventReceived
)
def invoice_notification(body: InvoiceEvent):
    pass  # pragma: nocover


class Event(BaseModel):
    name: str
    total: float


events_callback_router = APIRouter()


@events_callback_router.get("{$callback_url}/events/{$request.body.title}")
def event_callback(event: Event):