Control page content visibility based on URL parameter

Question

A visitor visits a page

for example: https://www.example.com/wp-login.php?action=rp&key=abc&login=jim

I want to have a block of text that displays only if the URL has ?action=rp

and a block of text that displays if the url is naked.

There are many content visibility plugins that can control visibility based on role etc.

But I can't find one that can control visibility based on a URL parameter.

Does one exist? If not, is there another way I can achieve that?

Answer 1

You can use add_shortcode() to register custom Shortcodes for restricting access to certain parts of the post content.

And here's a working example, with specific to your case:

function my_rp_shortcode( $atts = [], $content = '', $tag = '' ) {
    if ( 'if-rp' === $tag ) {
        // Return $content if the URL query string has action=rp.
        return ( isset( $_GET['action'] ) && 'rp' === $_GET['action'] ) ? $content : '';
    } else { // if-not-rp
        // Return $content if the URL query string doesn't have action=rp.
        return ( empty( $_GET['action'] ) || 'rp' !== $_GET['action'] ) ? $content : '';
    }
}
add_shortcode( 'if-rp', 'my_rp_shortcode' );
add_shortcode( 'if-not-rp', 'my_rp_shortcode' );

You'd add the code to the theme functions file and use the Shortcodes like so:

[if-rp]
This content is shown only if the query string "action" is set to "rp".
Example: example.com/login/?action=rp
[/if-rp]

[if-not-rp]
This content is shown only if the query string "action" is NOT set or the value is NOT "rp".
Example: example.com/login/?action= (empty "action")
Example 2: example.com/login/       (no "action")
[/if-not-rp]

You can change the logic, use two independent Shortcode functions, replace the tags (if-rp and if-not-rp), etc. if you want to. :)

Answer 2

If you don't want to use shortcodes you can use enqueue to add custom CSS to the header, add classes to your content and then toggle display none in CSS.

Add this to your functions.php or custom-functions.php file:

function wp_89494_enqueue_scripts() {
  if ( isset( $_GET['src'] ) && 'pc' === $_GET['src'] ) {
    wp_enqueue_style( 
      'wpse_89494_style_1', 
      get_stylesheet_directory_uri(). '/pcast.css' 
    );
  }
  
}

add_action( 'wp_enqueue_scripts', 'wpse_89494_enqueue_scripts' );

Then this to your url:

/?src=pc

And this to a file pcast.css placed in your child theme folder:

.stuff-to-hide {display:none !important;}

Inspired by this thread:

How to enqueue the style using wp_enqueue_style()