如何使用PHP在下拉菜单中仅显示具有相同page_id的元素？ 如何在foreach循环中编写“ if”语句？

Question

I have multiple dropdown menus and I only want to show subpages that have same page_id as the main pages in the dropdown.

I have two SQL tables:

'pages' => page_id, page_name; 
'subpages' => subpage_id, page_id, page_name;

Subpages get same page_id as the chosen parent page has, when I insert them via my form.

The problem is , all sub-pages are shown under every drop-down menu. I only want to show sub-pages under pages that share the same page_id. I suppose I need to write an IF statement in the foreach loop, but not sure how to do that..

index.php:

include_once('classes.php');

$page = new Page;
$subpage = new Subpage;

$pages = $page->fetch_all();
$subpages = $subpage->fetch_all();

<?php foreach ($pages as $page) { ?>

<button class="dropdown-btn">
  <?php echo $page['page_name']; ?>
</button>

<div class="dropdown-container">
  <?php foreach ($subpages as $subpage) { ?>

    <a href="../subpage.php?id=<?php echo $subpage['subpage_id']; ?>">
      <?php echo $subpage['subpage_name']; ?>
    </a>

  <?php } ?>
</div>

<?php } ?>

Summary: All subpages show under every pages dropdown - I would like to show subpages that share page_id with main pages. I suppose I need to write an IF statement in the foreach loop, but not sure how to do that..

Any help is appreciated!

Answer 1

You may match respective page_id show only if its related to main page

    <button class="dropdown-btn">
      <?php echo $page['page_name']; ?>
    </button>

    <div class="dropdown-container">
      <?php foreach ($subpages as $subpage) { 
          // match respective page_id show only if its related to main page
           if($subpage['page_id'] == $page['page_id'])
            {
      ?>

        <a href="../subpage.php?id=<?php echo $subpage['subpage_id']; ?>">
          <?php echo $subpage['subpage_name']; ?>
        </a>

      <?php } } ?>
    </div>

    <?php } ?>