How to get single value from get_post_meta() array of values?

Question

I'm trying to customize a plugin to check the current user's IP against previous IP values collected and stored by the plugin.

The plugin collects user votes for a custom post type called "competitors". The plugin also collects the IP of the user for each vote to prevent multiple votes by the user on a given competitor.

This is the code the plugin uses to store:

1. the most recent voter IP into a $key called "lastIP" in the wp_postmeta database table
2. all IPs that voted on the competitor into the next $key called "history" in the wp_postmeta database table (so there could be dozens of IPs stored in the "history" key array, along with a timestamp for each, and one of two other values depending on the vote type)

Existing code to store the values - works great:

function wps_update_history ( $thiscompetitor, $field, $value, $lastIP ) {

  update_post_meta($thiscompetitor, 'lastIP', $lastIP);

  $current_history = get_post_meta($thiscompetitor, 'history', true);
  $current_history_array = unserialize($current_history); 

  //push new values on
  $current_history_array[] = array ( current_time( "timestamp" ), $lastIP, $field, $value           );

  update_post_meta($thiscompetitor, 'history', serialize( $current_history_array ));
}

I've tried this to get the IP history list (to check if current user is in the list) but it is not working (within the post loop, with wp_query as orderby=>random) - from this post here

$hasIP = false;
    $histMeta = get_post_meta($post->ID, 'history', false);
        foreach($histMeta as $array) {
            if(isset($array['lastIP'])) {
                $hasIP = $array['lastIP'];
                break;
            }
        }
    echo $hasIP;

I've even tried to just echo the entire history array (for debugging) but can't even get this working.

    echo $histMeta;

Ultimately what I'd like to do is this logic:

if (current_user has their IP in this $post=>ID wp_postmeta 'history' key array) {
       // don't show or let them vote on this $post=>ID
    } else {
       // try another $post=>ID
        }

Any suggestions how I can achieve this logic above?

Answer 1

First, let met say that instead of echo, you should use var_dump or print_r for debugging. At first view, I see you are building a sequential array $current_history_array but you are trying to use it as associative array.

$current_history_array[] = array ( current_time( "timestamp" ), $lastIP, $field, $value           );

The above code generates a sequential array, for example:

array(
    '1424680884',
    '77.77.777.777',
    $field,
    $value
);

After, you are trying to access to lastIP key using $array['lastIP'] but such key doesn't exists. Instead, the last IP is stored in the index 2: $array[2]. If you want ot use associative arrays you have to build it as follow:

$current_history_array[] = array (
                               //The structure is key => value
                               'time'   => current_time( "timestamp" ),
                               'lastIP' => $lastIP,
                               'field'  => $field,
                               'value'  => $value          
);

The above code generates an array like this:

array(
    //The structure is key => value
    'timestamp' => '1424680884',
    'lastIP'    => '77.77.777.777',
    'field'     => $field,
    'value'     => $value
);

Now you can access to 'lastIP' key as $array['lastIP'].

Also, note that you store serialized data, so you have to unserialize it before use it as array:

$hasIP = false;
$histMeta = get_post_meta($post->ID, 'history', false);
    foreach($histMeta as $array) {

        $array = unserialize( $array );

        if(isset($array['lastIP'])) {
            $hasIP = $array['lastIP'];
            break;
        }

    }
echo $hasIP;