Using get_terms() seems to break editing experience of dynamic block

[carrieforde]

Describe the bug
Using get_terms() within a dynamic block's PHP seems to break the editing experience for the page on which the block lives.

This is what I expect to see when I try to edit the page on which this block lives:

Instead, I am redirected to a singular testimonial edit screen:

I have the following code to render a block in PHP:

/**
 * Build the markup for the testimonial tabs.
 * 
 * @param array $attributes The attributes passed from the editor.
 * @return string The markup.
 */
function fdr_content_blocks_testimonial_tabs( $attributes ) {

	$terms = get_terms( array(
		'taxonomy'   => 'fdrcf-testimonial-category',
		'hide_empty' => true,
	) );

	if ( empty( $terms ) || is_wp_error( $terms ) ) {
		return null;
	}

	ob_start();

	?>

	<div class="tabs">
		<div class="tabs__navigation">
			<?php foreach ( $terms as $term ) : ?>
				<?php if ( $term->term_id === $attributes['category'] ) : ?>
					<button id="<?php echo esc_attr( $term->slug ); ?>" class="tabs__button tabs__button--first tabs__button--active" role="tab" aria-selected="false" aria-controls="<?php echo esc_attr( $term->slug ); ?>-panel" tabindex="-1"><?php echo esc_html( $term->name ); ?></button>
				<?php else : ?>
					<button id="<?php echo esc_attr( $term->slug ); ?>" class="tabs__button" role="tab" aria-selected="false" aria-controls="<?php echo esc_attr( $term->slug ); ?>-panel" tabindex="-1"><?php echo esc_html( $term->name ); ?></button>
				<?php endif; ?>
			<?php endforeach; ?>
		</div>

		<?php foreach ( $terms as $term ) : ?>
			<div id="<?php echo esc_attr( $term->slug ); ?>-panel" class="tabs__panel" role="tabpanel" aria-labelledby="<?php echo esc_attr( $term->slug ); ?>" hidden="" tabindex="0">
				<?php get_posts_by_tax( $term->term_id ); ?>
			</div>
		<?php endforeach; ?>
	</div>

	<?php

	return ob_get_clean();
}

I have tried commenting out and reimplementing pieces of code to isolate the issue, and it seems like Gutenberg falls over because of the get_terms() call.

In case my actual query to get the posts is breaking my experience, here is that function:

/**
 * Get testimonials by term id.
 *
 * @param int $term_id The term being queried.
 */
function get_posts_by_tax( $term_id = 0 ) {

	$defaults = array(
		'post_type'      => 'fdrcf-testimonial',
		'posts_per_page' => 6,
		'tax_query'      => array(
			array(
				'taxonomy' => 'fdrcf-testimonial-category',
				'field'    => 'term_id',
				'terms'    => '',
			),
		),
	);
	$args = wp_parse_args( $args, $defaults );

	$post = array(
		'post_type'      => 'fdrcf-testimonial',
		'posts_per_page' => 6,
		'tax_query'      => array(
			array(
				'taxonomy' => 'fdrcf-testimonial-category',
				'field'    => 'term_id',
				'terms'    => $term_id,
			),
		),
	);

	$posts = new WP_Query( $post );

	if ( $posts->have_posts() ) {

		while ( $posts->have_posts() ) {

			$posts->the_post();

			$title = get_the_title();
			$title = explode( ' ', $title );

			$initials  = substr( $title[0], 0, 1 );
			$initials .= substr( $title[1], 0, 1 );

			$date = get_post_meta( get_the_ID(), 'testimonial_date', true );

			?>

			<article class="testimonial">
				<span class="testimonial__initials"><?php echo esc_html( $initials ); ?></span>

				<div class="testimonial__wrapper">
					<span class="star-rating"><?php display_stars(); ?></span>
					<?php echo the_content(); ?>
					<span class="testimonial__byline">&ndash;<?php echo get_the_title() . ', ' . esc_html( $date ); ?></span>
				</div>
			</article>

			<?php
		}
	}

	wp_reset_postdata();
}

To Reproduce
Steps to reproduce the behavior:

1. Implement a dynamic block that uses get_terms()
2. Add it to a page.
3. Try to edit the page and see if you are taken to the wrong edit screen.

Expected behavior
When I edit my Testimonials page, I expect to be taken to the edit screen for the page, not to the edit screen for a single testimonial.

Screenshots
See above

Desktop (please complete the following information):
n/a

Smartphone (please complete the following information):
n/a

Additional context

• Please add the version of Gutenberg you are using in the description.
  • Latest plugin version
• To report a security issue, please visit the WordPress HackerOne program: https://hackerone.com/wordpress.

[chrisvanpatten]

Thanks for the report @carrieforde! I'd strongly bet it's not specifically due to get_terms(), but is in fact the post query function. Running the $posts->the_post(); function causes the global $post variable to be reset, and wp_reset_postdata() doesn't currently work due to a Core bug.

You have a few options:

1. Iterate over the $posts->posts array directly and access the values directly (e.g. $post->post_title) rather than using the standard Loop functions
2. Save the global $post before running your loop functions, then set it again after your loop. There's a good example here

Hope this helps!

[Related to #8035 and #7582.]

[carrieforde]

Hi @chrisvanpatten! 👋

This seems to have done the trick. Super weird, but hey, I learned a thing! Thanks so much for your help.