Problems with using variables in php

  • Resolved brownca

    (@brownca)


    16 years, 8 months ago

    I’m having problems with a piece of code that sits in the sidebar of my posts. The code is supposed to get the category parent ID, assign it to a variable, and then use that variable when calling for the most recent posts from the category.

    <?php
foreach((get_the_category()) as $category) {
    $parent_id = $category->category_parent . ' ';
}; ?>

<?php echo $parent_id; ?>

<?php if(is_single()) {
	$my_query = new WP_Query('cat=$parent_id&order=desc&showposts=7'); ?>
<h2>Related Stories</h2>
<?php
	while ($my_query->have_posts()) : $my_query->the_post();
	$do_not_duplicate = $post->ID; ?>

<a href="<?php the_permalink(); ?>"><?php the_title(); ?></a>
<br />
<?php endwhile; }

?>

    The cat=%parent_id bit doesn’t seem to work (after $my_query = new WP_Query). When I replace %parent_id with (for example) 3, it correctly displays posts with category id 3. When I echo %parent_id it prints the correct category of the post, (for example – 3).

    So there’s really no reason why it shouldn’t be working, unless there’s something obvious I’ve missed. Any help will be very gratefully received. Thank you.

Viewing 7 replies - 1 through 7 (of 7 total)
  • MichaelH

    (@michaelh)

    16 years, 8 months ago

    Get category ID of first category on the single post

    if ( is_single() ) {
$category = get_the_category();
$category_id = $category[0]->cat_ID;
}

    Thread Starter brownca

    (@brownca)

    16 years, 8 months ago

    That doesn’t make any difference – the only difference that should make is getting the category id instead of the parent category id. Unfortunately it does neither, and just returns all posts regardless of category.

    I’m pretty sure it’s something to do with using a $variable in line 9 of my code above, since if I replace the variable after ” ‘cat= ” with a number of a category, the code works fine.

    I just don’t know why it won’t work with a variable containing a value, but it will work with the value on its own.

    MichaelH

    (@michaelh)

    16 years, 8 months ago

    What about

    if ( is_single() ) {
$category = get_the_category();
$category_id = $category[0]->cat_ID;
echo $category[0]->parent;
}
    Thread Starter brownca

    (@brownca)

    16 years, 8 months ago

    That part of the code isn’t the problem. I’ve already successfully stored the parent category ID, which I know because I checked with:
    <?php echo $parent_id; ?>
    When I’m viewing a post with category parent id 3, I will see the number 3 in the sidebar, so I know the variable should contain the number 3.

    The problem is this line:
    $my_query = new WP_Query('cat=$parent_id&order=desc&showposts=7'); ?>
    specifically the cat=$parent_id part. This doesn’t seem to be looking inside the variable $parent_id for the number 3, because it just returns posts from all categories. When I replace $parent_id with the number 3, the code works. But it shouldn’t make any difference, if you see what I mean?

    Thread Starter brownca

    (@brownca)

    16 years, 8 months ago

    Well, I’ve found a workaround for now by using an If statement for every single category, which makes for tons more code but it gets the job done. If anyone knows what I was doing wrong before with the variable I’d love to know.

    Thanks for your help MichaelH 🙂

    Mark / t31os

    (@t31os_)

    16 years, 8 months ago

    It’s because of the single quotes, you need to concatenate the string when using single quotes, where as double quotes allow literal variables in the string..

    $my_query = new WP_Query('cat=$parent_id&order=desc&showposts=7'); ?>

    fixed version.

    $my_query = new WP_Query('cat='.$parent_id.'&order=desc&showposts=7'); ?>

    or with double quotes.

    $my_query = new WP_Query("cat=$parent_id&order=desc&showposts=7"); ?>

    Using a good editor with syntax highlighting makes these kind of errors easy to spot.

    Thread Starter brownca

    (@brownca)

    16 years, 8 months ago

    Brilliant. Thanks very much, I’ll download a proper editor now to avoid mistakes like these in the future. Many thanks.

Viewing 7 replies - 1 through 7 (of 7 total)

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