[Resolved] Display field of an ACF relationship of all posts in a Query Loop

Hi there,

so when it comes to blocks and particularly those that create a loop, you can use the render_block filter to swap the content of a block with some other content.

1. Add a GB Block such as a Headline Block to your query loop.
1.1 Add some static text and NO dynamic data
1.2 In its Advanced > Additional CSS Class(es) add a custom class eg. your-custom-class
1.3 Note this class is used in the PHP snippet to target that block.

2. And here is an example of using the render_block filter to swap out that blocks content for you custom fields:

add_filter( 'render_block', function( $block_content, $block ) {
	
    // Set the conditions for render
    if (
        !is_admin() 
        && ! empty( $block['attrs']['className'] )
        && 'your-custom-class' === $block['attrs']['className'] // match class of your block
        ){
            // create a html variable
            $html = '';
            // get your custom field
            $relationships = get_field('relationship_field');
            // check the field has data 
            if( $relationships ) { 
                // loop through the field array
                foreach( $relationships as $relationship ) { 
                    // get the array itme fieldname 
                    $custom_field = get_field( 'field_name', $relationship->ID );
                }
                // print the custom field to the HTML
                $html .= '<span>' .  $custom_field . '</span>';
            }
            $block_content = $html;
    }
    
    return $block_content;

}, 10, 2 );

Update the className to match your CSS class on the block.
And update the code within the condition to output the fields you require.

You’re welcome