# Header Parameters { #header-parameters }

You can define Header parameters the same way you define `Query`, `Path` and `Cookie` parameters.

## Import `Header` { #import-header }

First import `Header`:

{* ../../docs_src/header_params/tutorial001_an_py310.py hl[3] *}

## Declare `Header` parameters { #declare-header-parameters }

Then declare the header parameters using the same structure as with `Path`, `Query` and `Cookie`.

func setEventStreamHeaders(w http.ResponseWriter) {
	w.Header().Set(xhttp.ContentType, "text/event-stream")
	w.Header().Set(xhttp.CacheControl, "no-cache") // nginx to turn off buffering
	w.Header().Set("X-Accel-Buffering", "no")      // nginx to turn off buffering
}

// Write http common headers
func setCommonHeaders(w http.ResponseWriter) {
	// Set the "Server" http header.
	w.Header().Set(xhttp.ServerInfo, MinioStoreName)

# Header Parameter Models { #header-parameter-models }

If you have a group of related **header parameters**, you can create a **Pydantic model** to declare them.

This would allow you to **re-use the model** in **multiple places** and also to declare validations and metadata for all the parameters at once. 😎

/// note

This is supported since FastAPI version `0.115.0`. 🤓

///

And as the `Response` can be used frequently to set headers and cookies, **FastAPI** also provides it at `fastapi.Response`.

///

## Custom Headers { #custom-headers }

Keep in mind that custom proprietary headers can be added <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers" class="external-link" target="_blank">using the 'X-' prefix</a>.

        requestHeaders =
          listOf(
            Header(Header.TARGET_METHOD, "GET"),
            Header(Header.TARGET_SCHEME, "https"),
            Header(Header.TARGET_AUTHORITY, "squareup.com"),
            Header(Header.TARGET_PATH, "/cached"),
          ),
      )
    peer
      .sendFrame()
      .headers(
        outFinished = true,
        streamId = 2,
        headerBlock =

      )

    fun http2HeadersList(request: Request): List<Header> {
      val headers = request.headers
      val result = ArrayList<Header>(headers.size + 4)
      result.add(Header(TARGET_METHOD, request.method))
      result.add(Header(TARGET_PATH, RequestLine.requestPath(request.url)))
      val host = request.header("Host")
      if (host != null) {
        result.add(Header(TARGET_AUTHORITY, host)) // Optional.
      }

	// and don't process the If-Modified-Since header.
	if objInfo.ModTime.IsZero() || objInfo.ModTime.Equal(time.Unix(0, 0)) {
		return false
	}

	// Headers to be set of object content is not going to be written to the client.
	writeHeaders := func() {
		// set common headers
		setCommonHeaders(w)

		// set object-related metadata headers
		w.Header().Set(xhttp.LastModified, objInfo.ModTime.UTC().Format(http.TimeFormat))

					i, o, l, skip, sn, ps, oRef, lRef, skipRef, snRef, psRef)
			}
		}
	}
}

var getDefaultOptsTests = []struct {
	headers        http.Header
	copySource     bool
	metadata       map[string]string
	encryptionType encrypt.Type
	err            error
}{
	{
		headers: http.Header{
			xhttp.AmzServerSideEncryptionCustomerAlgorithm: []string{"AES256"},

      }

    /** Removes all headers on this builder and adds [headers]. */
    open fun headers(headers: Headers) =
      apply {
        this.headers = headers.newBuilder()
      }

    /**
     * Sets this request's `Cache-Control` header, replacing any cache control headers already
     * present. If [cacheControl] doesn't define any directives, this clears this request's
     * cache-control headers.

        CurlResponse response = new CurlResponse();
        Map<String, List<String>> headers = new HashMap<>();
        headers.put("Content-Type", Arrays.asList("application/json"));
        headers.put("CONTENT-LENGTH", Arrays.asList("100"));
        headers.put("accept-encoding", Arrays.asList("gzip"));
        response.setHeaders(headers);

        // All header access should be case-insensitive