Can I override the content array using the_posts filter?

Question

So I am pretty new to WordPress and as a learning exercise I am trying to create a membership plugin that will allow the site to restrict access to pages based on user type.

The first step I am doing is just trying to remove page content and display a "membership only area" message. At first I was going to try injecting JavaScript that would remove everything from <*div id="content">, but I was not sure if custom themes are required to use that div id.

I am now trying to use the filter the_content to rewrite the content. I can remove the content completely by not returning the content but then it just shows a "content not found" message. So I am now trying to re-write the array itself by doing $content['post_content'] = "Members only"; . Instead of changing the post_content it prints it to the screen twice.

I might be on the completely wrong path for what I am trying to do but still, how would I go about re-writing the $content array so that WordPress would display the fake content that I want it to display?

Answer 1

The the_content filter will work for this. This filter allows you to alter the output of the_content() and get_the_content():

add_filter( 'the_content', 'wpse_members_only', 20 );
function wpse_members_only( $content ) {
    // If user is not logged in, show restricted content message.
    // Change this conditional statement based on how you want to check for
    // membership status. I'd suggest using capabilites, e.g. current_user_can( $capability , $object_id );
    if ( ! is_user_logged_in() ) {
        $content = __( 'Sorry, this content is reserved for members only.', 'text-domain' );
    }

    return $content;
}