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is_site_meta_supported()

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概述

is_site_meta_supported() 函数用于检查站点元数据（site meta）是否启用，通过验证 'blogmeta' 数据库表是否存在。结果作为主网络的全局设置缓存，避免重复查询。

关键要点

  • 函数检查 'blogmeta' 表是否存在，以确定站点元数据支持状态
  • 结果缓存在网络选项中（site_meta_supported），提升性能
  • 仅在多站点（Multisite）环境下有效，非多站点返回 false
  • 返回布尔值：true 表示支持，false 表示不支持

代码示例

function is_site_meta_supported() {
	global $wpdb;

	if ( ! is_multisite() ) {
		return false;
	}

	$network_id = get_main_network_id();

	$supported = get_network_option( $network_id, 'site_meta_supported', false );
	if ( false === $supported ) {
		$supported = $wpdb->get_var( "SHOW TABLES LIKE '{$wpdb->blogmeta}'" ) ? 1 : 0;

		update_network_option( $network_id, 'site_meta_supported', $supported );
	}

	return (bool) $supported;
}

注意事项

  • 函数首次调用时会执行数据库查询，后续调用使用缓存值
  • 相关函数包括 update_network_option()、get_network_option()、get_main_network_id() 等
  • 自 WordPress 5.1.0 版本引入
📄 原文内容

Determines whether site meta is enabled.

Description

This function checks whether the ‘blogmeta’ database table exists. The result is saved as a setting for the main network, making it essentially a global setting. Subsequent requests will refer to this setting instead of running the query.

Return

bool True if site meta is supported, false otherwise.

Source

function is_site_meta_supported() {
	global $wpdb;

	if ( ! is_multisite() ) {
		return false;
	}

	$network_id = get_main_network_id();

	$supported = get_network_option( $network_id, 'site_meta_supported', false );
	if ( false === $supported ) {
		$supported = $wpdb->get_var( "SHOW TABLES LIKE '{$wpdb->blogmeta}'" ) ? 1 : 0;

		update_network_option( $network_id, 'site_meta_supported', $supported );
	}

	return (bool) $supported;
}

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Uses Description
update_network_option()wp-includes/option.php

Updates the value of a network option that was already added.
get_network_option()wp-includes/option.php

Retrieves a network’s option value based on the option name.
get_main_network_id()wp-includes/functions.php

Gets the main network ID.
is_multisite()wp-includes/load.php

Determines whether Multisite is enabled.
wpdb::get_var()wp-includes/class-wpdb.php

Retrieves one value from the database.

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Used by Description
wp_check_site_meta_support_prefilter()wp-includes/ms-site.php

Aborts calls to site meta if it is not supported.
wp_delete_site()wp-includes/ms-site.php

Deletes a site from the database.
populate_site_meta()wp-admin/includes/schema.php

Creates WordPress site meta and sets the default values.
upgrade_network()wp-admin/includes/upgrade.php

Executes network-level upgrade routines.

Changelog

Version Description
5.1.0 Introduced.