如果自定义 post 类型与匹配当前课程页面 ID 的课程 ID 相关，则在旁边显示标题

Display aside title if custom post type is related to course ID matching current course page ID

我下面的当前代码始终显示标题 'course instructors'，当我需要它在没有课程讲师的情况下消失时。

我需要发生的事情是：

您需要执行检查此课程是否有任何培训师的逻辑，然后您可以对结果执行任何检查。 此外，将您的逻辑移出 html 是个好主意。 Wordpress 并没有使这变得简单，但我们至少可以执行文件顶部的逻辑：

<?php
//lets get all our logic out of the html
$trainersArray = array(
    'post_type'      => 'trainers',
    'posts_per_page' => -1,
    'orderby' => 'name',
    'order' => 'ASC'
);
query_posts($trainersArray);

$trainers = get_posts( $trainersArray );

//an array to hold any trainers for this specific course
$courseTrainers = [];

foreach ( $trainers as $trainer ) {

    $trainer_courses = get_field('courses',$trainer->ID);  //SELECT THE CONNECTED COURSE'S CUSTOM FIELD

    if(!$trainer_courses){
        continue; //no need to carry on this iteration
    }

    $fullName = get_the_title($trainer->ID); //GET THE NAME FIELD IN TESTIMONIAL POSTS
    $trainerPage = get_the_permalink($trainer->ID);

    foreach( $trainer_courses as $trainer_course ){
        //i presume $Course_ID is set elsewhere but is in scope?
        if($trainer_course->ID == $Course_ID){
            $courseTrainers[] = [
                'fullName'=>$fullName,
                'pageLink'=>$trainerPage
            ];
            break; //no further iterations needed
        }
    }
}
wp_reset_query();
?>
<div class="instructors">
    <?php if(count($courseTrainers)>0)://an empty array is falsey,but this is more explicit?>

        <h3 id="trainers_heading">Course Instructors</h3><!-- only show this if there is instructors to show -->

    <?php endif;?>

    <div id="trainers_list">
        <?php foreach($courseTrainers as $trainer):?>
            <div class="instructor-block">
                <div class="instructor-profile ">
                    <div class="profile-name">
                        <?php echo $trainer['fullName']; ?>
                    </div>
                    <div class="profile-link">
                        <a href="<?php echo $trainer['pageLink']; ?>">
                            View Full Profile
                        </a>
                    </div>
                </div>
            </div><!-- Your BR has been eradicated Feranndo - long live css ;-)-->
        <?php endforeach;?>

    </div><!-- .trainers_list -->
</div><!-- .instructors -->

以下是在主要问题变得清晰之前发现的一些其他问题，但仍然值得在答案中保留：

1：您正在使用较短的开放标签，这些标签已过时并且可能是问题所在，更改：

  <? if (!$trainers) { }else{?><h3 id="trainers_heading">Course Instructors</h3><!-- only show this if there is instructors to show --><? } ?>
//^short tag                                                                                                                           ^another

至：

<?php if (!$trainers) { }else{?><h3 id="trainers_heading">Course Instructors</h3><!-- only show this if there is instructors to show --><?php } ?>

2：双重否定很奇怪，改成

<?php if ($trainers){?><h3 id="trainers_heading">Course Instructors</h3><!-- only show this if there is instructors to show --><?php } ?>

3：$trainers 直到检查后才声明，因此将该代码向上移动：

<?php 

    $trainersArray = array(
       'post_type'      => 'trainers',
       'posts_per_page' => -1,
       'orderby' => 'name',
       'order' => 'ASC'
    );
    query_posts($trainersArray);

    $trainers = get_posts( $trainersArray );

?>
<div class="instructors">
    <?php if ($trainers){?><h3 id="trainers_heading">Course Instructors</h3><!-- only show this if there is instructors to show --><?php } ?>
<div id="trainers_list">
    <?php                         
    foreach ( $trainers as $trainer ) {...

5：最后，不要在if():endif; 和if(){} 语法之间切换，这会造成混淆。使用 html 时，首选前者，因此最终代码变为：

<div class="instructors">

    <?php
    $trainersArray = array(
        'post_type'      => 'trainers',
        'posts_per_page' => -1,
        'orderby' => 'name',
        'order' => 'ASC'
    );
    query_posts($trainersArray);

    $trainers = get_posts( $trainersArray );
    ?>

    <?php if($trainers):?>

    <h3 id="trainers_heading">Course Instructors</h3><!-- only show this if there is instructors to show -->

    <?php endif;?>

    <div id="trainers_list">
        <?php

        foreach ( $trainers as $trainer ) :

            $trainerID = $trainer->ID;
            $trainer_courses = get_field('courses',$trainerID);  //SELECT THE CONNECTED COURSE'S CUSTOM FIELD
            $fullName = get_the_title($trainerID); //GET THE NAME FIELD IN TESTIMONIAL POSTS
            $trainerPage = get_the_permalink($trainerID);
            $feedback_count = 0;

            if( $trainer_courses ):

                foreach( $trainer_courses as $trainer_course ):

                    $trainerCourseID = $trainer_course->ID;

                    if ($trainerCourseID == $Course_ID) : ?>
                        <div class="instructor-block">
                            <div class="instructor-profile ">
                                <div class="profile-name">
                                    <?php echo $fullName; ?>
                                </div>
                                <div class="profile-link">
                                    <a href="<?php echo $trainerPage; ?>">
                                        View Full Profile
                                    </a>
                                </div>
                            </div>
                        </div><br><!-- Another BR Feranndo? and it's not even in body text, its after a DIV, whats your problem? -->
                    <?php 
                    endif;

                endforeach; 

            endif; 

        endforeach; 
        wp_reset_query(); ?>

    </div><!-- .trainers_list -->
</div><!-- .instructors -->