How to Paginate lines in a foreach loop with PHP

问题:

Using the following code to display a list of friends from my twitter profile. Id like to only load a certain number at a time, say 20, then provide pagination links at the bottom for First 1-2-3-4-5(however many divided by limit) Last

$xml = simplexml_load_string($rawxml);

foreach ($xml->id as $key => $value) 
{
    $profile           = simplexml_load_file("https://twitter.com/users/$value");
    $friendscreenname  = $profile->{"screen_name"};
    $profile_image_url = $profile->{"profile_image_url"};

    echo "<a href=$profile_image_url>$friendscreenname</a><br>";
}

******update******

if (!isset($_GET['i'])) {
    $i = 0;
} else {
    $i = (int) $_GET['i'];
}

$limit  = $i + 10;
$rawxml = OauthGetFriends($consumerkey, $consumersecret, $credarray[0], $credarray[1]);
$xml    = simplexml_load_string($rawxml);

foreach ($xml->id as $key => $value)
{

    if ($i >= $limit) {
        break;
    }

    $i++;
    $profile           = simplexml_load_file("https://twitter.com/users/$value");
    $friendscreenname  = $profile->{"screen_name"};
    $profile_image_url = $profile->{"profile_image_url"};

    echo "<a href=$profile_image_url>$friendscreenname</a><br>";
}

echo "<a href=step3.php?i=$i>Next 10</a><br>";

This works, just have to offset the output starting at $i. Thinking array_slice?

回答1:

A very elegant solution is using a LimitIterator:

$xml = simplexml_load_string($rawxml);
// can be combined into one line
$ids = $xml->xpath('id'); // we have an array here
$idIterator = new ArrayIterator($ids);
$limitIterator = new LimitIterator($idIterator, $offset, $count);
foreach($limitIterator as $value) {
    // ...
}

// or more concise
$xml = simplexml_load_string($rawxml);
$ids = new LimitIterator(new ArrayIterator($xml->xpath('id')), $offset, $count);
foreach($ids as $value) {
    // ...
}

回答2:

If you're loading the full dataset every time, you could be pretty direct about it and use a for loop instead of a foreach:

$NUM_PER_PAGE = 20;

$firstIndex = ($page-1) * $NUM_PER_PAGE;

$xml = simplexml_load_string($rawxml);
for($i=$firstIndex; $i<($firstIndex+$NUM_PER_PAGE); $i++)
{
        $profile = simplexml_load_file("https://twitter.com/users/".$xml->id[$i]);
        $friendscreenname = $profile->{"screen_name"};
        $profile_image_url = $profile->{"profile_image_url"};
        echo "<a href=$profile_image_url>$friendscreenname</a><br>";
}

You'll also need to limit $i to the array length, but hopefully you get the gist.