根據設置的值合併數組值

Question

目前，我試圖讓我的URL縮短腳本能夠跟蹤來自Google Analytics的UTM變量。我也想提供我自己的（廣告系列/關鍵字/源/等...）變量。我試圖篩選$ _GET，挑出「批准的」鍵/值對，並設置每個鍵的條件是UTM變量具有更高的優先級（我只想在數據庫中存儲一個值）。

我的代碼是目前：

//Parse $_GET and only get the key/pairs that we need and store them in global $url_params for use through out the script 
function set_url_params($allowed=NULL) { // $allowed is arg to add new values in future dev 
global $url_params; 

$allowed = array( 
    'l', // Redirect key (e.g http://example.com?l=a1dFd7) 
    'utm_campaign', 
    'campaign', 
    'utm_source' , 
    'source', 
    'utm_medium', 
    'medium', 
    'utm_term', 
    'term', 
    'keyword', 
    'kw', 
    ); 

    $approved = array_intersect_key($_GET, array_flip($allowed)); 

    foreach($approved as $key => $value) { 
     strip_tags(urldecode(trim($value))); 
     $url_params[$key] = $value; 
    } 

    //Assign variables to global $url_params variable so other functions can use them. 
    //NOTE: Google Analytics UTM parameters take precedence over script values. 
    $url_params['l'] = isset($approved['l']) ? $approved['l'] : NULL ; 
    $url_params['campaign'] = isset($approved['utm_campaign']) ? $approved['utm_campaign'] : $approved['campaign']; 
    $url_params['source'] = isset($approved['utm_source']) ? $approved['utm_source'] : $approved['source']; 
    $url_params['medium'] = isset($approved['utm_medium']) ? $approved['utm_medium'] : $approved['medium']; 
    $url_params['term'] = isset($approved['utm_term']) ? $approved['utm_term'] : $approved['term']; 
    $url_params['keyword'] = isset($approved['keyword']) ? $approved['keyword'] : $approved['kw']; 
    // Just in case $url_params doesn't have a 'keyword' set, we will use 'term' instead. 
    $url_params['keyword'] = isset($url_params['keyword']) ? $url_params['keyword'] : $url_params['term']; 

} 

我基本上要找到這樣做的更清潔的方式，不用所有isset（）函數的。我還會收到NOTICE錯誤（在E_ALL中運行）未定義的變量，我想要取消設置，因此我不會收到這些錯誤。

Answer 1

大概是這樣嗎？

$params = array(
    'l'  => array('default' => null), 
    'campaign' => array('default' => null, 'alt' => 'utm_campaign'), 
    ... 
); 

$url_params = array(); 

foreach ($params as $key => $info) { 
    $url_params[$key] = $info['default']; 
    if (isset($info['alt'], $_GET[$info['alt']])) { 
     $url_params[$key] = $_GET[$info['alt']]; 
    } 
    if (isset($_GET[$key]) { 
     $url_params[$key] = $_GET[$key]; 
    } 
}