How to hide first gallery for every post?

Question

I'm using galleries for attaching images, so the very first gallery for every post is used to generate a slider and nothing more. That's why I don't want to see it in post's conent. Let's say I have a single post that looks like this:

[gallery ids="1,2"] // hide
[gallery ids="3,4"] // display 
[gallery ids="5,6"] // display

Is there some way of blocking the very first gallery from the content for every post?

#gallery-1 { display: none !important; } 

works good but is ugly as hell :) Also it only hides the gallery but it's still there, same goes for it's JS.

Answer 1

You could use preg_replace() but I think it's much easier to overwrite the $output via the post_gallery filter and then remove the filter after the first run:

/**
 * Remove the output of the first gallery
 *
 * @param string $output
 * @param array $attr
 * @return string $output
 */
function wpse125903_remove_the_first_gallery( $output, $attr )
{
    // Run only once
    remove_filter( current_filter(), __FUNCTION__ );

    // Override the first gallery output        
    return '<!-- gallery 1 was here -->';   // Must be non-empty.
}

add_filter( 'post_gallery', 'wpse125903_remove_the_first_gallery', 10, 2 );

This should remove only the first gallery in your posts.