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send_headers

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概述

send_headers 是一个 WordPress 动作钩子，在 HTTP 响应头（如缓存、内容类型等）发送后触发，用于向响应中添加自定义头部信息。

关键要点

  • send_headers 钩子在 HTTP 响应头发送后执行，允许开发者添加或修改头部。
  • 从 WordPress 6.1 起，此钩子触发时间移至 pre_get_posts 之后，支持使用条件标签（如 is_single、is_404）。
  • 参数为 $wp（WordPress 环境实例，按引用传递），可通过 do_action_ref_array 调用。
  • 常用于添加如 X-UA-Compatible 或 X-Robots-Tag 等自定义 HTTP 头，以优化浏览器兼容性或 SEO 控制。

代码示例

add_action( 'send_headers', 'add_header_xua' );
function add_header_xua() {
    header( 'X-UA-Compatible: IE=edge,chrome=1' );
}
add_action( 'send_headers', function() {
    if ( '0' != get_option( 'blog_public' ) || ( defined( 'WP_DEBUG' ) && true == WP_DEBUG ) ) {
        header( 'X-Robots-Tag: noindex, nofollow', true );
    }
}, 99 );

注意事项

  • 使用 header() 函数添加头部时，需确保在输出内容前调用，避免错误。
  • 从 WordPress 6.1 开始，钩子触发时机变化，可能影响依赖早期触发的代码，需检查兼容性。
  • 示例代码展示了如何条件性设置头部，并可通过优先级参数（如 99）控制执行顺序。
📄 原文内容

Fires once the requested HTTP headers for caching, content type, etc. have been sent.

Description

The ‘wp_finalized_template_enhancement_output_buffer’ action may be used to send headers after rendering the template into an output buffer.

Parameters

$wpWP
Current WordPress environment instance (passed by reference).

More Information

This action hook is used to add additional headers to the outgoing HTTP response.

Source

do_action_ref_array( 'send_headers', array( &$this ) );

View all references View on Trac View on GitHub

Used by Description
WP::send_headers()wp-includes/class-wp.php

Sends additional HTTP headers for caching, content type, etc.

Changelog

Version Description
2.1.0 Introduced.

User Contributed Notes

  1. Skip to note 5 content


    Daniel Roch


    You must log in to vote on the helpfulness of this noteVote results for this note: 1You must log in to vote on the helpfulness of this note

    Since WordPress 6.1, the send_headers action has been moved to later in core load. It is now triggered after pre_get_posts.

    Conditionals tags can now be used (is_single, is_404 and so on).

    More information on this dev-note: https://make.wordpress.org/core/2022/10/10/moving-the-send_headers-action-to-later-in-the-load/

  2. Skip to note 6 content


    Collins Mbaka


    You must log in to vote on the helpfulness of this noteVote results for this note: 0You must log in to vote on the helpfulness of this note

    As an example: HTML5 Boilerplate provides an X-UA-Compatible meta element by default. This element breaks validation but can be moved to a header. Adding the following to functions.php fixes the validation issue and provides IE users a better experience.

    add_action( 'send_headers', 'add_header_xua' );
function add_header_xua() {
	header( 'X-UA-Compatible: IE=edge,chrome=1' );
}

  3. Skip to note 7 content


    Steven Lin


    You must log in to vote on the helpfulness of this noteVote results for this note: 0You must log in to vote on the helpfulness of this note

    Example migrated from Codex:

    As an example: HTML5 Boilerplate provides an X-UA-Compatible meta element by default. This element breaks validation, but can be moved to a header. Adding the following to functions.php fixes the validation issue and provides IE users a better experience.

    add_action( 'send_headers', 'add_header_xua' );
function add_header_xua() {
	header( 'X-UA-Compatible: IE=edge,chrome=1' );
}

  4. Skip to note 8 content


    wp_kc


    You must log in to vote on the helpfulness of this noteVote results for this note: 0You must log in to vote on the helpfulness of this note

    Example of how to conditionally send a header, replacing previously set header, if any…

    /**
 * Send "X-Robots-Tag: noindex, nofollow" header if not a public web site. 
 * If WP_DEBUG is true, treat web site as if it is non-public.
 */
add_action( 'send_headers', function() {
	if ( '0' != get_option( 'blog_public' ) || ( defined( 'WP_DEBUG' ) && true == WP_DEBUG ) ) {
		/**
		 * Tell robots not to index or follow
		 * Set header replace parameter to true
		 */
		header( 'X-Robots-Tag: noindex, nofollow', true );
	}
}, 99 );  // Try to execute last with priority set to 99