[Resolved] How to add nofollow to affiliate links

[Chris]

Would you know how to automatically add nofollow to all affiliate links?

I read this article, but it didn’t help. It would give me a PHP error.

Any ideas on how to get this to work?

[David]

Hi there,

what was the error?

[Chris]

Here’s the error I’m getting: http://prntscr.com/qhxlup

Here’s what I added in the functions.php file: http://prntscr.com/qhxlhu

[David]

Looks like you got a bunch of errors in the code – if you compare your functions.php code to the original you will see a lot of the HTML has been escaped. You will need to correct the code so it matches that on the blog you got it from.

[Chris]

I don’t see anything missing (maybe because I don’t understand coding, haha). Could you correct the code:

// Add no-follow tags for specific domain strings
function add_nofollow( $content ) {

    $az_url = "amazon1.com";
    preg_match_all( '~<a.*>~isU', $content, $uri_match );

    for ( $i = 0; $i <= sizeof( $uri_match[0] ); $i ++ ) {
        if ( isset( $uri_match[0][ $i ] ) && ! preg_match( '~nofollow~is', $uri_match[0][ $i ] )
             && ( preg_match( '~' . preg_quote( $az_url ) . '~', $uri_match[0][ $i ] ))
            ) {
            $uri_change = trim( $uri_match[0][ $i ], ">" );
            $uri_change .= ' rel="nofollow">';
            $content = str_replace( $uri_match[0][ $i ], $uri_change, $content );
        }
    }

    $az_url = "amazon2.com";
    preg_match_all( '~<a.*>~isU', $content, $uri_match );

    for ( $i = 0; $i <= sizeof( $uri_match[0] ); $i ++ ) {
        if ( isset( $uri_match[0][ $i ] ) && ! preg_match( '~nofollow~is', $uri_match[0][ $i ] )
             && ( preg_match( '~' . preg_quote( $az_url ) . '~', $uri_match[0][ $i ] ))
            ) {
            $uri_change = trim( $uri_match[0][ $i ], ">" );
            $uri_change .= ' rel="nofollow">';
            $content = str_replace( $uri_match[0][ $i ], $uri_change, $content );
        }
    }

$az_url = "amazon2.com";
    preg_match_all( '~<a.*>~isU', $content, $uri_match );

    for ( $i = 0; $i <= sizeof( $uri_match[0] ); $i ++ ) {
        if ( isset( $uri_match[0][ $i ] ) && ! preg_match( '~nofollow~is', $uri_match[0][ $i ] )
             && ( preg_match( '~' . preg_quote( $az_url ) . '~', $uri_match[0][ $i ] ))
            ) {
            $uri_change = trim( $uri_match[0][ $i ], ">" );
            $uri_change .= ' rel="nofollow">';
            $content = str_replace( $uri_match[0][ $i ], $uri_change, $content );
        }
    }

$az_url = "amazon2.com";
    preg_match_all( '~<a.*>~isU', $content, $uri_match );

    for ( $i = 0; $i <= sizeof( $uri_match[0] ); $i ++ ) {
        if ( isset( $uri_match[0][ $i ] ) && ! preg_match( '~nofollow~is', $uri_match[0][ $i ] )
             && ( preg_match( '~' . preg_quote( $az_url ) . '~', $uri_match[0][ $i ] ))
            ) {
            $uri_change = trim( $uri_match[0][ $i ], ">" );
            $uri_change .= ' rel="nofollow">';
            $content = str_replace( $uri_match[0][ $i ], $uri_change, $content );
        }
    }

$az_url = "amazon2.com";
    preg_match_all( '~<a.*>~isU', $content, $uri_match );

    for ( $i = 0; $i <= sizeof( $uri_match[0] ); $i ++ ) {
        if ( isset( $uri_match[0][ $i ] ) && ! preg_match( '~nofollow~is', $uri_match[0][ $i ] )
             && ( preg_match( '~' . preg_quote( $az_url ) . '~', $uri_match[0][ $i ] ))
            ) {
            $uri_change = trim( $uri_match[0][ $i ], ">" );
            $uri_change .= ' rel="nofollow">';
            $content = str_replace( $uri_match[0][ $i ], $uri_change, $content );
        }
    }

$az_url = "amazon2.com";
    preg_match_all( '~<a.*>~isU', $content, $uri_match );

    for ( $i = 0; $i <= sizeof( $uri_match[0] ); $i ++ ) {
        if ( isset( $uri_match[0][ $i ] ) && ! preg_match( '~nofollow~is', $uri_match[0][ $i ] )
             && ( preg_match( '~' . preg_quote( $az_url ) . '~', $uri_match[0][ $i ] ))
            ) {
            $uri_change = trim( $uri_match[0][ $i ], ">" );
            $uri_change .= ' rel="nofollow">';
            $content = str_replace( $uri_match[0][ $i ], $uri_change, $content );
        }
    }

$az_url = "amazon2.com";
    preg_match_all( '~<a.*>~isU', $content, $uri_match );

    for ( $i = 0; $i <= sizeof( $uri_match[0] ); $i ++ ) {
        if ( isset( $uri_match[0][ $i ] ) && ! preg_match( '~nofollow~is', $uri_match[0][ $i ] )
             && ( preg_match( '~' . preg_quote( $az_url ) . '~', $uri_match[0][ $i ] ))
            ) {
            $uri_change = trim( $uri_match[0][ $i ], ">" );
            $uri_change .= ' rel="nofollow">';
            $content = str_replace( $uri_match[0][ $i ], $uri_change, $content );
        }
    }

$az_url = "amazon2.com";
    preg_match_all( '~<a.*>~isU', $content, $uri_match );

    for ( $i = 0; $i <= sizeof( $uri_match[0] ); $i ++ ) {
        if ( isset( $uri_match[0][ $i ] ) && ! preg_match( '~nofollow~is', $uri_match[0][ $i ] )
             && ( preg_match( '~' . preg_quote( $az_url ) . '~', $uri_match[0][ $i ] ))
            ) {
            $uri_change = trim( $uri_match[0][ $i ], ">" );
            $uri_change .= ' rel="nofollow">';
            $content = str_replace( $uri_match[0][ $i ], $uri_change, $content );
        }
    }

    $az_url = "amazon3.com";
    preg_match_all( '~<a.*>~isU', $content, $uri_match );

    for ( $i = 0; $i <= sizeof( $uri_match[0] ); $i ++ ) {
        if ( isset( $uri_match[0][ $i ] ) && ! preg_match( '~nofollow~is', $uri_match[0][ $i ] )
             && ( preg_match( '~' . preg_quote( $az_url ) . '~', $uri_match[0][ $i ] ))
            ) {
            $uri_change = trim( $uri_match[0][ $i ], ">" );
            $uri_change .= ' rel="nofollow">';
            $content = str_replace( $uri_match[0][ $i ], $uri_change, $content );
        }
    }

    return $content;
}

add_filter( 'the_content', 'add_nofollow' );

[Leo]

This is something you will need to check with the code author unfortunately.

We can’t really help with custom functions that coming from an external source.

[Chris]

Thanks! Got it to work!

[Leo]

No problem 🙂

[Author]

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