php - WordPress - fatal error : Call to a member function get_var() on a non-object $wpdb

Question

[Solution by s_ha_dum on http://wordpress.stackexchange.com]

我试图根据在帖子设置中输入的密码将用户定向到某个帖子。我几乎有工作代码:

页面上的表单:

<form method="post" action="">
  <input type="password" name="passwordfield">
  <input type="hidden" name="homepagepassword" value="1">
  <input type="submit" value="Submit">
</form>

functions.php 中的代码

function doPasswordStuff(){
    if(isset($_POST['homepagepassword'])){
    $post_password = $_POST['passwordfield'];
    $post_id = $wpdb->get_var( $wpdb->prepare("SELECT ID FROM $wpdb->posts WHERE post_password = %s", $post_password) );
    $q = new WP_Query( 'p=$post_id' );
    if($q->have_posts()){
        while($q->have_posts()){
            $q->the_post();
            wp_redirect(get_permalink());
            die();
        }
    } else {
        // oh dear, there isnt a post with this 'password', put a redirect to a fallback here
        wp_redirect('http://www.google.com');
        die();
    }
    wp_reset_query();
    }
}
add_action('init','doPasswordStuff');

但是我在这一行遇到 fatal error ( fatal error :调用非对象上的成员函数 get_var()):

$post_id = $wpdb->get_var( $wpdb->prepare("SELECT ID FROM $wpdb->posts WHERE post_password = %d", $post_password) );

如果有人愿意看一下，我将不胜感激 :) 谢谢!

Answer 1

在此之前全局化$wpdb

global $wpdb

$post_id = $wpdb->get_var( $wpdb->prepare("SELECT id FROM $wpdb->posts WHERE post_password = %s", $post_password) ); $q = new WP_Query( 'p=$post_id' );

最好使用小写的表/列名

然后像这样重定向

<?php if ( $q->have_posts() ) : while ( $q->have_posts() ) : $q->the_post(); ?>

wp_redirect( the_permalink() );

<?php endif;?>

还使用 http 状态代码作为 wp_redirect() 的第二个参数这可能会有所帮助 HTTP STATUS CODES