Question

I have the below function in WordPress.
However, the meta key product_price is duplicated each time a post is updated.

Like this image

Is there any way to prevent this?

 function do_my_stuff($post_ID) {
global $post,$wpdb;
$tablename="wp_cart66_products";
if($post->post_type == "post" && strlen( get_post_meta($post_ID, 'price', true))>0        )
{
    $id = $wpdb->get_var("SELECT id FROM ".$tablename." WHERE id=".$post_ID);
    $cny = get_post_meta($post->ID, 'price', true);



   /*Shipping rate */
    if( $cny < 50 )
        $shipping = 14.97;

    else if( $cny >= 50 && $cny < 200 )

        $shipping = 22.59;  

       else if( $cny >= 200 && $cny < 250 )

        $shipping = 24.59;

        else if( $cny >= 250 && $cny < 300 )

        $shipping = 26.60;


    else if( $cny >= 300 )
        $shipping = 29.27;  

    /*Exchange rate  CNY to EURO */

    $cny_to_euro = 0.124;
    $euro =     $cny * $cny_to_euro ;   
    $price = $euro + $shipping;
    $price = number_format($price,2);
    $data=array(
        'id'=>$post_ID,
        'item_number'=>get_post_meta($post->ID, 'scode', true),
        'name'=>$post->post_title,
        'price'=>$price,
        'options_1'=>get_post_meta($post->ID, 'variations', true),
        'shipped'=>'1',
    );
    $where = array("id" => $post_ID);
    // Possible format values: %s as string; %d as decimal number; and %f as               float.
    $format=array( '%d', '%s', '%s', '%s', '%s', '%d');
    $where_format = array( '%d' );
    if($id>0){
        // update
        $wpdb->update( $tablename,$data, $where, $format, $where_format);
    }else{

        // insert
        $wpdb->insert( $tablename,$data,$format);
    }

    AddMetaPrice ( $post_ID ) ; 
}
return $post_ID;
          }
       function AddMetaPrice ( $post_ID ) 
          {
// init
global $post,$wpdb;

// We add the wordpress post ID and price to a meta tag
$metaKey = "product_price" ; 
$tableName = "wp_cart66_products" ; 
$metaQuery = "SELECT price FROM $tableName WHERE id='$post_ID'" ; 
$metaValue = $wpdb->get_var( $metaQuery ) ; 
$tableName = "wp_postmeta" ; 

// Do we have this post already?
if ( $id > 0 ) 
{
    // this already exists. we only need to update
    // $metaQuery = "UPDATE $tableName SET meta_value='$metaValue' WHERE                  meta_key='$metaKey' AND post_id='$id'" ; // we use wordpress's method instead
    $data = array ( "meta_value" => $metaValue ) ; 
    $where = array ( "meta_key" => $metaKey, "post_id" => $post_ID ) ; 
    $wpdb->update( $tableName, $data, $where ) ; 
}
else 
{
    // this is not created, we need to create it now (insert)
    // $metaQuery = "INSERT INTO $tableName (post_id, meta_key, meta_value)  VALUES ('$id', '$metaKey', '$metaValue')" ; // we use wordpress's method instead
    $data = array ( "post_id" => $post_ID, "meta_key" => $metaKey, "meta_value" => $metaValue ) ; 
    $wpdb->insert( $tableName, $data ) ; 
 }
    }
   add_action('publish_post', 'do_my_stuff');

I’ve read here that a ON DUPLICATE KEY statement exists. But i’m not sure if it can be implemented in the above code.

Answer 1

Try replacing that piece of code:

if ( $metaValue !== NULL ) 
{
   update_post_meta($post_ID, $metaKey, $metaValue); // use built-in function instead
}

where it was:

// Do we have this post already?
if ( $id > 0 ) 
{
    // this already exists. we only need to update
    // $metaQuery = "UPDATE $tableName SET meta_value='$metaValue' WHERE                  meta_key='$metaKey' AND post_id='$id'" ; // we use wordpress's method instead
    $data = array ( "meta_value" => $metaValue ) ; 
    $where = array ( "meta_key" => $metaKey, "post_id" => $post_ID ) ; 
    $wpdb->update( $tableName, $data, $where ) ; 
}