Guido Scialfa

Hello,

To upload a file programmatically into the upload dir you should use wp_handle_upload

Uhm, you’re right.

I made some changes and I think the only way to remove the duplicated image is to perform a check with the ID of the featured image and the image within the content.

Have a look at this new one.
The function get the post thumbnail ID and compare it with the ID get from the wp-image- class value. Generally WordPress add that class with the ID of the image.

If the post has not a featured image or the ID of the first image found is not the same of the post thumbnail ID nothing will be performed.

If this code work correctly, we can try to remove the image directly within this function.

Sorry for the issue, I thought that you had all posts with the duplicated image.

Let me know.

 
function xx_remove_first_image( $content ) {

	if ( ! is_singular( 'post' ) || ! is_main_query() ) {
		return $content;
	}

	// Get the featured image.
	$_fthumb = absint( get_post_thumbnail_id() );

	// Do nothing if the post hasn't a featured image.
	if ( ! $_fthumb ) {
		return $content;
	}

	// Try to retrieve the ID of the attachment.
	if ( preg_match( '/<img class=\".*wp\-image\-([\d]{1,}).*\" [^>]*>/', $content, $matches ) && ! empty( $matches[1] ) ) {
		$_id = absint( $matches[1] );

		// And compare it with the featured image thumbnail.
		if ( $_id === $_fthumb ) {
			preg_match( '/(<img [^>]*>)/', $content, $matches );

			if ( ! empty( $matches[1] ) ) {
				$content = str_replace( $matches[1], '', $content );
			}
		}
	}

	return $content;

}
add_filter( 'the_content', 'xx_remove_first_image' );

Of course, try the code below. Consider in this case the image will be removed only in single post post-type.

function xx_remove_first_image( $content ) {

	if ( is_singular( 'post' ) && preg_match( '/(<img [^>]*>)/', $content, $matches ) ) {
		$content = str_replace( $matches[1], '', $content );
	}

	return $content;
}
add_filter( 'the_content', 'xx_remove_first_image', 20 );

Regarding the way to remove them from the post during update or insert you should consider that every first image will be removed even if it is not a duplicated of the featured image.

Hello,

Try this snippet in functions.php at the end of the file.

function xx_remove_first_image( $content ) {

	if ( preg_match( '/(<img [^>]*>)/', $content, $matches ) ) {
		$content = str_replace( $matches[1], '', $content );
	}

	return $content;
}
add_filter( 'the_content', 'xx_remove_first_image', 20 );

That should remove the first image within the post content. But will not remove it from the content itself, simply the image will not be shown up.

If you want to remove completely the image from the post content, you need to hook into the wp_insert_post_data filter. In this case make a database backup first.