# 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)

)

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 {

     * Creates a CURL request from the provided header string.
     *
     * @param header the header string containing HTTP method and path
     * @return CURL request object or null if header is invalid
     */
    private CurlRequest getCurlRequest(final String header) {
        if (StringUtil.isBlank(header)) {
            return null;
        }

        final String[] values = header.split(" ");
        if (values.length != 2) {

	reader, err := sio.DecryptReader(client, sio.Config{
		Key:            objectEncryptionKey,
		SequenceNumber: seqNumber,
	})
	if err != nil {
		return nil, crypto.ErrInvalidCustomerKey
	}
	return reader, nil
}

// DecryptBlocksRequestR - same as DecryptBlocksRequest but with a
// reader

import org.codelibs.core.lang.StringUtil;

/**
 * Represents an HTTP request header with a name and value.
 * This class is used to encapsulate the header information for HTTP requests.
 * It provides methods to get and set the name and value of the header,
 * as well as a method to validate the header.
 *
 * <p>Example usage:</p>
 * <pre>
 *     RequestHeader header = new RequestHeader("Content-Type", "application/json");

	}
}

var isHTTPHeaderSizeTooLargeTests = []struct {
	header     http.Header
	shouldFail bool
}{
	{header: generateHeader(0, 0), shouldFail: false},
	{header: generateHeader(1024, 0), shouldFail: false},
	{header: generateHeader(2048, 0), shouldFail: false},
	{header: generateHeader(8*1024+1, 0), shouldFail: true},
	{header: generateHeader(0, 1024), shouldFail: false},
	{header: generateHeader(0, 2048), shouldFail: true},

        .protocols(ONLY_HTTP1)
        .build()
    val request =
      originalRequest
        .newBuilder()
        .header("Upgrade", "websocket")
        .header("Connection", "Upgrade")
        .header("Sec-WebSocket-Key", key)
        .header("Sec-WebSocket-Version", "13")
        .header("Sec-WebSocket-Extensions", "permessage-deflate")
        .build()
    call = RealCall(webSocketClient, request, forWebSocket = true)