How to rename array keys in PHP?

Question

You could use array_map() to do it.

$tags = array_map(function($tag) {
    return array(
        'name' => $tag['name'],
        'value' => $tag['url']
    );
}, $tags);

Loop through, set new key, unset old key.

foreach($tags as &$val){
    $val['value'] = $val['url'];
    unset($val['url']);
}

Talking about functional PHP, I have this more generic answer:

    array_map(function($arr){
        $ret = $arr;
        $ret['value'] = $ret['url'];
        unset($ret['url']);
        return $ret;
    }, $tag);
}

Recursive php rename keys function:

function replaceKeys($oldKey, $newKey, array $input){
    $return = array(); 
    foreach ($input as $key => $value) {
        if ($key===$oldKey)
            $key = $newKey;

        if (is_array($value))
            $value = replaceKeys( $oldKey, $newKey, $value);

        $return[$key] = $value;
    }
    return $return; 
}

foreach ($basearr as &$row)
{
    $row['value'] = $row['url'];
    unset( $row['url'] );
}

unset($row);

This should work in most versions of PHP 4+. Array map using anonymous functions is not supported below 5.3.

Also the foreach examples will throw a warning when using strict PHP error handling.

Here is a small multi-dimensional key renaming function. It can also be used to process arrays to have the correct keys for integrity throughout your app. It will not throw any errors when a key does not exist.

function multi_rename_key(&$array, $old_keys, $new_keys)
{
    if(!is_array($array)){
        ($array=="") ? $array=array() : false;
        return $array;
    }
    foreach($array as &$arr){
        if (is_array($old_keys))
        {
            foreach($new_keys as $k => $new_key)
            {
                (isset($old_keys[$k])) ? true : $old_keys[$k]=NULL;
                $arr[$new_key] = (isset($arr[$old_keys[$k]]) ? $arr[$old_keys[$k]] : null);
                unset($arr[$old_keys[$k]]);
            }
        }else{
            $arr[$new_keys] = (isset($arr[$old_keys]) ? $arr[$old_keys] : null);
            unset($arr[$old_keys]);
        }
    }
    return $array;
}

Usage is simple. You can either change a single key like in your example:

multi_rename_key($tags, "url", "value");

or a more complex multikey

multi_rename_key($tags, array("url","name"), array("value","title"));

It uses similar syntax as preg_replace() where the amount of $old_keys and $new_keys should be the same. However when they are not a blank key is added. This means you can use it to add a sort if schema to your array.

Use this all the time, hope it helps!