from fastapi import FastAPI, Header
from pydantic import BaseModel

app = FastAPI()


class CommonHeaders(BaseModel):
    host: str
    save_data: bool
    if_modified_since: Union[str, None] = None
    traceparent: Union[str, None] = None
    x_tag: list[str] = []


@app.get("/items/")
async def read_items(headers: CommonHeaders = Header()):

                                "in": "header",
                                "required": True,
                                "schema": {"type": "string", "title": "Host"},
                            },
                            {
                                "name": "save-data",
                                "in": "header",
                                "required": True,

When writing request headers, use `header(name, value)` to set the only occurrence of `name` to `value`. If there are existing values, they will be removed before the new value is added. Use `addHeader(name, value)` to add a header without removing the headers already present.

      networkHeaders: Headers,
    ): Headers {
      val result = Headers.Builder()

      for (index in 0 until cachedHeaders.size) {
        val fieldName = cachedHeaders.name(index)
        val value = cachedHeaders.value(index)
        if ("Warning".equals(fieldName, ignoreCase = true) && value.startsWith("1")) {
          // Drop 100-level freshness warnings.
          continue
        }

		}
	}
}

// Tests validate metadata extraction from http headers.
func TestExtractMetadataHeaders(t *testing.T) {
	testCases := []struct {
		header     http.Header
		metadata   map[string]string
		shouldFail bool
	}{
		// Validate if there a known 'content-type'.
		{
			header: http.Header{
				"Content-Type": []string{"image/png"},
			},
			metadata: map[string]string{

    multipartBody.writeTo(buffer)

    val multipartReader = MultipartReader(buffer, "foo")
    val onlyPart = multipartReader.nextPart()!!
    assertThat(onlyPart.headers).isEqualTo(
      headersOf(
        "header-name",
        "header-value",
        "Content-Type",
        "application/octet-stream",
      ),
    )
    val readBuff = Buffer()
    var byteCount = 0L
    while (true) {

	rw := httptest.NewRecorder()
	trw := &trackingResponseWriter{ResponseWriter: rw}

	if headersAlreadyWritten(trw) {
		t.Fatal("headers have not been written yet")
	}

	trw.WriteHeader(123)
	if !headersAlreadyWritten(trw) {
		t.Fatal("headers were written")
	}
}

func TestHeadersAlreadyWrittenWrapped(t *testing.T) {
	rw := httptest.NewRecorder()

from fastapi import FastAPI, Header
from pydantic import BaseModel

app = FastAPI()


class CommonHeaders(BaseModel):
    host: str
    save_data: bool
    if_modified_since: str | None = None
    traceparent: str | None = None
    x_tag: list[str] = []


@app.get("/items/")
async def read_items(headers: CommonHeaders = Header(convert_underscores=False)):

from fastapi import FastAPI, Header
from pydantic import BaseModel

app = FastAPI()


class CommonHeaders(BaseModel):
    host: str
    save_data: bool
    if_modified_since: str | None = None
    traceparent: str | None = None
    x_tag: list[str] = []


@app.get("/items/")
async def read_items(
    headers: Annotated[CommonHeaders, Header(convert_underscores=False)],
):

from fastapi import FastAPI, Header
from pydantic import BaseModel

app = FastAPI()


class CommonHeaders(BaseModel):
    host: str
    save_data: bool
    if_modified_since: Union[str, None] = None
    traceparent: Union[str, None] = None
    x_tag: list[str] = []


@app.get("/items/")
async def read_items(headers: Annotated[CommonHeaders, Header()]):