# 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`. 🤓

///

	}
}

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},

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

	if objInfo.ETag != "" {
		w.Header()[xhttp.ETag] = []string{"\"" + objInfo.ETag + "\""}
	}

	if objInfo.VersionID != "" {
		w.Header()[xhttp.AmzVersionID] = []string{objInfo.VersionID}
	}

	if !objInfo.Expires.IsZero() {

	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)
		}

        byte[] header = buildHeader(NtStatus.NT_STATUS_INVALID_PARAMETER);
        byte[] body = buildErrorBody(2, 3, new byte[] { (byte) 0xAA, (byte) 0xBB, (byte) 0xCC });
        byte[] packet = new byte[header.length + body.length];
        System.arraycopy(header, 0, packet, 0, header.length);
        System.arraycopy(body, 0, packet, header.length, body.length);

        header.originalMessageSize = SMBUtil.readInt4(buffer, bufferIndex);
        bufferIndex += 4;

        // Skip reserved (2 bytes)
        bufferIndex += 2;

        // Read flags
        header.flags = SMBUtil.readInt2(buffer, bufferIndex);
        bufferIndex += 2;

        // Read session ID
        header.sessionId = SMBUtil.readInt8(buffer, bufferIndex);

        return header;
    }

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)

import okhttp3.internal.http.promisesBody
import okhttp3.internal.http2.Header.Companion.RESPONSE_STATUS_UTF8
import okhttp3.internal.http2.Header.Companion.TARGET_AUTHORITY
import okhttp3.internal.http2.Header.Companion.TARGET_AUTHORITY_UTF8
import okhttp3.internal.http2.Header.Companion.TARGET_METHOD
import okhttp3.internal.http2.Header.Companion.TARGET_METHOD_UTF8
import okhttp3.internal.http2.Header.Companion.TARGET_PATH

                        .status(ApiResult.Status.OK)
                        .result());
    }

    /**
     * Retrieves a specific request header setting by ID.
     *
     * @param id the ID of the request header setting to retrieve
     * @return JSON response containing the request header setting
     */
    // GET /api/admin/reqheader/setting/{id}
    @Execute
    public JsonResponse<ApiResult> get$setting(final String id) {