辛星浅析WordPress中的get_option

    WordPress使用get_option()来获取通过option表单设置值的方法，如果数据库中不存在该选项，或者改选项的值为空，那么将会返回一个false。

    通过get_option获得的值通常都可以在后台的"菜单"->"常规"中获得。而且它们内容如下：

    admin_email   管理员的email地址

    blogname      网站title标题

    blogscription   网站描述

    blog_charset   网站编码，一般都是utf-8

    date_format    日期格式

    default_category    文章默认分类

    home         网站地址

    siteurl       WordPress的web地址

    template      当前主题名称

    start_of-week    星期开始设置

    upload_path      上传默认目录

     posts_per_page   文章分页每页显示的数量

    posts_per_rss     rss聚合显示的最新文章数量

  

    需要注意的是该函数可以接受两个参数，如果查询的第一个参数不存在时，就会返回第二个参数。

    如果只写一个参数，那么当查询的第一个参数不存在时，将会返回false。

    get-option（）位于wp-includes/option.php文件中，其函数的源代码部分（3.9版本）如下：

/** * Option API * * @package WordPress * @subpackage Option *//** * Retrieve option value based on name of option. * * If the option does not exist or does not have a value, then the return value * will be false. This is useful to check whether you need to install an option * and is commonly used during installation of plugin options and to test * whether upgrading is required. * * If the option was serialized then it will be unserialized when it is returned. * * @since 1.5.0 * * @param string $option Name of option to retrieve. Expected to not be SQL-escaped. * @param mixed $default Optional. Default value to return if the option does not exist. * @return mixed Value set for the option. */function get_option( $option, $default = false ) {global $wpdb;$option = trim( $option );if ( empty( $option ) )return false;/** * Filter the value of an existing option before it is retrieved. * * The dynamic portion of the hook name, $option, refers to the option name. * * Passing a truthy value to the filter will short-circuit retrieving * the option value, returning the passed value instead. * * @since 1.5.0 * * @param bool|mixed $pre_option Value to return instead of the option value. *                               Default false to skip it. */$pre = apply_filters( 'pre_option_' . $option, false );if ( false !== $pre )return $pre;if ( defined( 'WP_SETUP_CONFIG' ) )return false;if ( ! defined( 'WP_INSTALLING' ) ) {// prevent non-existent options from triggering multiple queries$notoptions = wp_cache_get( 'notoptions', 'options' );if ( isset( $notoptions[$option] ) )/** * Filter the default value for an option. * * The dynamic portion of the hook name, $option, refers * to the option name. * * @since 3.4.0 * * @param mixed $default The default value to return if the option *                       does not exist in the database. */return apply_filters( 'default_option_' . $option, $default );$alloptions = wp_load_alloptions();if ( isset( $alloptions[$option] ) ) {$value = $alloptions[$option];} else {$value = wp_cache_get( $option, 'options' );if ( false === $value ) {$row = $wpdb->get_row( $wpdb->prepare( "SELECT option_value FROM $wpdb->options WHERE option_name = %s LIMIT 1", $option ) );// Has to be get_row instead of get_var because of funkiness with 0, false, null valuesif ( is_object( $row ) ) {$value = $row->option_value;wp_cache_add( $option, $value, 'options' );} else { // option does not exist, so we must cache its non-existence$notoptions[$option] = true;wp_cache_set( 'notoptions', $notoptions, 'options' );/** This filter is documented in wp-includes/option.php */return apply_filters( 'default_option_' . $option, $default );}}}} else {$suppress = $wpdb->suppress_errors();$row = $wpdb->get_row( $wpdb->prepare( "SELECT option_value FROM $wpdb->options WHERE option_name = %s LIMIT 1", $option ) );$wpdb->suppress_errors( $suppress );if ( is_object( $row ) ) {$value = $row->option_value;} else {/** This filter is documented in wp-includes/option.php */return apply_filters( 'default_option_' . $option, $default );}}// If home is not set use siteurl.if ( 'home' == $option && '' == $value )return get_option( 'siteurl' );if ( in_array( $option, array('siteurl', 'home', 'category_base', 'tag_base') ) )$value = untrailingslashit( $value );/** * Filter the value of an existing option. * * The dynamic portion of the hook name, $option, refers to the option name. * * @since 1.5.0 As 'option_' . $setting * @since 3.0.0 * * @param mixed $value Value of the option. If stored serialized, it will be *                     unserialized prior to being returned. */return apply_filters( 'option_' . $option, maybe_unserialize( $value ) );}