描述
获取上一篇或下一篇相邻的文章。
语法
get_adjacent_post( bool $in_same_term = false, array|string $excluded_terms = \'\', bool $previous = true, string $taxonomy = \'category\' )参数
$in_same_term：(bool) (Optional)( Default value: false) 文章是否在同一分类
$excluded_terms：(array|string) (Optional) (Default value: \’\’) 排除分类的ID
$previous：(boolean) (Optional) (Default value: true) 是否获取上一篇文章
$taxonomy：(string) (Optional)(Default value: \’category\’) 如果 $in_same_term 设置为 表示限定的分类
返回值
WP_Post：如果成功，返回文章对 象。
Null：如果 global $post 没有设置，返回空值Null。
String：如果不存在符合条件的文章 ，返回空字符串。
示例
获取同分类下的上一篇文章。
<?php $prev_post = get_adjacent_post( true, \'\', true, \'taxonomy_slug\' ); ?><?php if ( is_a( $prev_post, \'WP_Post\' ) ) { ?> <a href=\"<?php%20echo%20get_permalink(%20$prev_post->ID%20);%20?>\"><?php echo get_the_title( $prev_post->ID ); ?></a><?php } ?>获取同分类下的下一篇文章。
<?php $next_post = get_adjacent_post( true, \'\', false, \'taxonomy_slug\' ); ?><?php if ( is_a( $next_post, \'WP_Post\' ) ) { ?> <a href=\"<?php%20echo%20get_permalink(%20$next_post->ID%20);%20?>\"><?php echo get_the_title( $next_post->ID ); ?></a><?php } ?>关系
被用
wp-includes/link-template.php: get_adjacent_post_link()
wp-includes/link-template.php: get_previous_post()
wp-includes/link-template.php: get_next_post()
wp-includes/link-template.php: get_adjacent_post_rel_link()
源码
位置： wp-includes/link-template.php
function get_adjacent_post( $in_same_term = false, $excluded_terms = \'\', $previous = true, $taxonomy = \'category\' ) { global $wpdb; if ( ( ! $post = get_post() ) || ! taxonomy_exists( $taxonomy ) ) return null; $current_post_date = $post->post_date; $join = \'\'; $where = \'\'; $adjacent = $previous ? \'previous\' : \'next\'; if ( $in_same_term || ! empty( $excluded_terms ) ) { if ( ! empty( $excluded_terms ) && ! is_array( $excluded_terms ) ) { // back-compat, $excluded_terms used to be $excluded_terms with IDs separated by \" and \" if ( false !== strpos( $excluded_terms, \' and \' ) ) { _deprecated_argument( __FUNCTION__, \'3.3.0\', sprintf( __( \'Use commas instead of %s to separate excluded terms.\' ), \"\'and\'\" ) ); $excluded_terms = explode( \' and \', $excluded_terms ); } else { $excluded_terms = explode( \',\', $excluded_terms ); } $excluded_terms = array_map( \'intval\', $excluded_terms ); } if ( $in_same_term ) { $join .= \" INNER JOIN $wpdb->term_relationships AS tr ON p.ID = tr.object_id INNER JOIN $wpdb->term_taxonomy tt ON tr.term_taxonomy_id = tt.term_taxonomy_id\"; $where .= $wpdb->prepare( \"AND tt.taxonomy = %s\", $taxonomy ); if ( ! is_object_in_taxonomy( $post->post_type, $taxonomy ) ) return \'\'; $term_array = wp_get_object_terms( $post->ID, $taxonomy, array( \'fields\' => \'ids\' ) ); // Remove any exclusions from the term array to include. $term_array = array_diff( $term_array, (array) $excluded_terms ); $term_array = array_map( \'intval\', $term_array ); if ( ! $term_array || is_wp_error( $term_array ) ) return \'\'; $where .= \" AND tt.term_id IN (\" . implode( \',\', $term_array ) . \")\"; } /** * Filters the IDs of terms excluded from adjacent post queries. * * The dynamic portion of the hook name, `$adjacent`, refers to the type * of adjacency, \'next\' or \'previous\'. * * @since 4.4.0 * * @param string $excluded_terms Array of excluded term IDs. */ $excluded_terms = apply_filters( \"get_{$adjacent}_post_excluded_terms\", $excluded_terms ); if ( ! empty( $excluded_terms ) ) { $where .= \" AND p.ID NOT IN ( SELECT tr.object_id FROM $wpdb->term_relationships tr LEFT JOIN $wpdb->term_taxonomy tt ON (tr.term_taxonomy_id = tt.term_taxonomy_id) WHERE tt.term_id IN (\" . implode( \',\', array_map( \'intval\', $excluded_terms ) ) . \') )\'; } } // \'post_status\' clause depends on the current user. if ( is_user_logged_in() ) { $user_id = get_current_user_id(); $post_type_object = get_post_type_object( $post->post_type ); if ( empty( $post_type_object ) ) { $post_type_cap = $post->post_type; $read_private_cap = \'read_private_\' . $post_type_cap . \'s\'; } else { $read_private_cap = $post_type_object->cap->read_private_posts; } /* * Results should include private posts belonging to the current user, or private posts where the * current user has the \'read_private_posts\' cap. */ $private_states = get_post_stati( array( \'private\' => true ) ); $where .= \" AND ( p.post_status = \'publish\'\"; foreach ( (array) $private_states as $state ) { if ( current_user_can( $read_private_cap ) ) { $where .= $wpdb->prepare( \" OR p.post_status = %s\", $state ); } else { $where .= $wpdb->prepare( \" OR (p.post_author = %d AND p.post_status = %s)\", $user_id, $state ); } } $where .= \" )\"; } else { $where .= \" AND p.post_status = \'publish\'\"; } $op = $previous ? \'<\' : \'>\'; $order = $previous ? \'DESC\' : \'ASC\'; /** * Filters the JOIN clause in the SQL for an adjacent post query. * * The dynamic portion of the hook name, `$adjacent`, refers to the type * of adjacency, \'next\' or \'previous\'. * * @since 2.5.0 * @since 4.4.0 Added the `$taxonomy` and `$post` parameters. * * @param string $join The JOIN clause in the SQL. * @param bool $in_same_term Whether post should be in a same taxonomy term. * @param array $excluded_terms Array of excluded term IDs. * @param string $taxonomy Taxonomy. Used to identify the term used when `$in_same_term` is true. * @param WP_Post $post WP_Post object. */ $join = apply_filters( \"get_{$adjacent}_post_join\", $join, $in_same_term, $excluded_terms, $taxonomy, $post ); /** * Filters the WHERE clause in the SQL for an adjacent post query. * * The dynamic portion of the hook name, `$adjacent`, refers to the type * of adjacency, \'next\' or \'previous\'. * * @since 2.5.0 * @since 4.4.0 Added the `$taxonomy` and `$post` parameters. * * @param string $where The `WHERE` clause in the SQL. * @param bool $in_same_term Whether post should be in a same taxonomy term. * @param array $excluded_terms Array of excluded term IDs. * @param string $taxonomy Taxonomy. Used to identify the term used when `$in_same_term` is true. * @param WP_Post $post WP_Post object. */ $where = apply_filters( \"get_{$adjacent}_post_where\", $wpdb->prepare( \"WHERE p.post_date $op %s AND p.post_type = %s $where\", $current_post_date, $post->post_type ), $in_same_term, $excluded_terms, $taxonomy, $post ); /** * Filters the ORDER BY clause in the SQL for an adjacent post query. * * The dynamic portion of the hook name, `$adjacent`, refers to the type * of adjacency, \'next\' or \'previous\'. * * @since 2.5.0 * @since 4.4.0 Added the `$post` parameter. * @since 4.9.0 Added the `$order` parameter. * * @param string $order_by The `ORDER BY` clause in the SQL. * @param WP_Post $post WP_Post object. * @param string $order Sort order. \'DESC\' for previous post, \'ASC\' for next. */ $sort = apply_filters( \"get_{$adjacent}_post_sort\", \"ORDER BY p.post_date $order LIMIT 1\", $post, $order ); $query = \"SELECT p.ID FROM $wpdb->posts AS p $join $where $sort\"; $query_key = \'adjacent_post_\' . md5( $query ); $result = wp_cache_get( $query_key, \'counts\' ); if ( false !== $result ) { if ( $result ) $result = get_post( $result ); return $result; } $result = $wpdb->get_var( $query ); if ( null === $result ) $result = \'\'; wp_cache_set( $query_key, $result, \'counts\' ); if ( $result ) $result = get_post( $result ); return $result;}© 版权声明
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