WordPress 免插件去除分类链接中「category」字样

如题，WordPress 免插件去除分类链接中「category」字样。有这个需求的同学可以参考一下。代码提取自插件：No Category Base (WPML)，不想折腾可以直接用插件。

<?php
/*去除 Category 目录 提取自 No Category Base (WPML) https://wordpress.org/plugins/no-category-base-wpml/*/

/* hooks */
register_activation_hook(__FILE__,    'no_category_base_refresh_rules');
//register_deactivation_hook(__FILE__,  'no_category_base_deactivate');

/* actions */
add_action('created_category',  'no_category_base_refresh_rules');
add_action('delete_category',   'no_category_base_refresh_rules');
add_action('edited_category',   'no_category_base_refresh_rules');
add_action('init',              'no_category_base_permastruct');

/* filters */
add_filter('category_rewrite_rules', 'no_category_base_rewrite_rules');
add_filter('query_vars',             'no_category_base_query_vars');    // Adds 'category_redirect' query variable
add_filter('request',                'no_category_base_request');       // Redirects if 'category_redirect' is set

function no_category_base_refresh_rules() {
	global $wp_rewrite;
	$wp_rewrite->flush_rules();
}

function no_category_base_deactivate() {
	remove_filter( 'category_rewrite_rules', 'no_category_base_rewrite_rules' ); // We don't want to insert our custom rules again
	no_category_base_refresh_rules();
}

function no_category_base_permastruct()
{
	global $wp_rewrite;
	global $wp_version;

	if ( $wp_version >= 3.4 ) {
		$wp_rewrite->extra_permastructs['category']['struct'] = '%category%';
	} else {
		$wp_rewrite->extra_permastructs['category'][0] = '%category%';
	}
}

function no_category_base_rewrite_rules($category_rewrite) {
	global $wp_rewrite;
	$category_rewrite=array();

	/* WPML is present: temporary disable terms_clauses filter to get all categories for rewrite */
	if ( class_exists( 'Sitepress' ) ) {
		global $sitepress;

		remove_filter( 'terms_clauses', array( $sitepress, 'terms_clauses' ) );
		$categories = get_categories( array( 'hide_empty' => false ) );
		//Fix provided by Albin here https://wordpress.org/support/topic/bug-with-wpml-2/#post-8362218
		//add_filter( 'terms_clauses', array( $sitepress, 'terms_clauses' ) );
		add_filter( 'terms_clauses', array( $sitepress, 'terms_clauses' ), 10, 4 );
	} else {
		$categories = get_categories( array( 'hide_empty' => false ) );
	}

	foreach( $categories as $category ) {
		$category_nicename = $category->slug;

		if ( $category->parent == $category->cat_ID ) {
			$category->parent = 0;
		} elseif ( $category->parent != 0 ) {
			$category_nicename = get_category_parents( $category->parent, false, '/', true ) . $category_nicename;
		}

		$category_rewrite['('.$category_nicename.')/(?:feed/)?(feed|rdf|rss|rss2|atom)/?$'] = 'index.php?category_name=$matches[1]&feed=$matches[2]';
		$category_rewrite["({$category_nicename})/{$wp_rewrite->pagination_base}/?([0-9]{1,})/?$"] = 'index.php?category_name=$matches[1]&paged=$matches[2]';
		$category_rewrite['('.$category_nicename.')/?$'] = 'index.php?category_name=$matches[1]';
	}

	// Redirect support from Old Category Base
	$old_category_base = get_option( 'category_base' ) ? get_option( 'category_base' ) : 'category';
	$old_category_base = trim( $old_category_base, '/' );
	$category_rewrite[$old_category_base.'/(.*)$'] = 'index.php?category_redirect=$matches[1]';

	return $category_rewrite;
}

function no_category_base_query_vars($public_query_vars) {
	$public_query_vars[] = 'category_redirect';
	return $public_query_vars;
}

function no_category_base_request($query_vars) {
	if( isset( $query_vars['category_redirect'] ) ) {
		$catlink = trailingslashit( get_option( 'home' ) ) . user_trailingslashit( $query_vars['category_redirect'], 'category' );
		status_header( 301 );
		header( "Location: $catlink" );
		exit();
	}
	return $query_vars;
}

注意：不管安装插件或使用代码均可能出现 404 页面，即设置的固定链接伪静态失效了！

解决方法：登录后台→设置→固定链接设置页面，随意改一下固定链接格式，然后再改回正常使用的固定链接格式即可。如果还会出现 404，可以尝试清除缓存！