# 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`.

# 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`. 🤓

///

    /**
     * Add a header with the specified name and formatted date. Does validation of header names and
     * value.
     */
    fun add(
      name: String,
      value: Date,
    ) = add(name, value.toHttpDateString())

    /**
     * Add a header with the specified name and formatted instant. Does validation of header names
     * and value.
     */

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)

}

// setPutObjHeaders sets all the necessary headers returned back
// upon a success Put/Copy/CompleteMultipart/Delete requests
// to activate delete only headers set delete as true
func setPutObjHeaders(w http.ResponseWriter, objInfo ObjectInfo, del bool, h http.Header) {
	// We must not use the http.Header().Set method here because some (broken)
	// clients expect the ETag header key to be literally "ETag" - not "Etag" (case-sensitive).

	defer func(flag bool) { globalIsTLS = flag }(globalIsTLS)
	globalIsTLS = true
	for i, test := range encryptRequestTests {
		content := bytes.NewReader(make([]byte, 64))
		req := &http.Request{Header: http.Header{}}
		for k, v := range test.header {
			req.Header.Set(k, v)
		}
		_, _, err := EncryptRequest(content, req, "bucket", "object", test.metadata)
		if err != nil {
			t.Fatalf("Test %d: Failed to encrypt request: %v", i, err)
		}

      )

    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.
      }

        // The header remains for subsequent tests due to static request handling
        // Different matching header added to same request
        request.addHeader("X-Forwarded-Host", "test.com");
        result = virtualHostHelper.getVirtualHostPath(page);
        assertEquals("/site1/search", result.getRoutingPath()); // Still site1 due to header precedence
    }

    public void test_getVirtualHostBasePath() {

)

func getDefaultOpts(header http.Header, copySource bool, metadata map[string]string) (opts ObjectOptions, err error) {
	var clientKey [32]byte
	var sse encrypt.ServerSide

	opts = ObjectOptions{UserDefined: metadata}
	if v, ok := header[xhttp.MinIOSourceProxyRequest]; ok {
		opts.ProxyHeaderSet = true
		opts.ProxyRequest = strings.Join(v, "") == "true"
	}
	if _, ok := header[xhttp.MinIOSourceReplicationRequest]; ok {

		if crypto.S3.IsEncrypted(info.UserDefined) && r.Header.Get(xhttp.AmzCopySource) == "" {
			if crypto.SSEC.IsRequested(headers) || crypto.SSECopy.IsRequested(headers) {
				return encrypted, errEncryptedObject
			}
		}

		if crypto.S3KMS.IsEncrypted(info.UserDefined) && r.Header.Get(xhttp.AmzCopySource) == "" {
			if crypto.SSEC.IsRequested(headers) || crypto.SSECopy.IsRequested(headers) {
				return encrypted, errEncryptedObject