从PHP对象数组中获取单个值

Question

I am very new to PHP and I want to grab a single value from the OpenGraph object and print it. Not sure what I am doing wrong? I keep getting "Array" as the print out.

class OpenGraph implements Iterator{

public static $TYPES = array(
    'activity' => array('activity', 'sport'),
    'business' => array('bar', 'company', 'cafe', 'hotel', 'restaurant'),
    'group' => array('cause', 'sports_league', 'sports_team'),
    'organization' => array('band', 'government', 'non_profit', 'school', 'university'),
    'person' => array('actor', 'athlete', 'author', 'director', 'musician', 'politician', 'public_figure'),
    'place' => array('city', 'country', 'landmark', 'state_province'),
    'product' => array('album', 'book', 'drink', 'food', 'game', 'movie', 'product', 'song', 'tv_show'),
    'website' => array('blog', 'website'),
);

private $_values = array();

static public function fetch($URI) {
    $curl = curl_init($URI);
    curl_setopt($curl, CURLOPT_FAILONERROR, true);
    curl_setopt($curl, CURLOPT_FOLLOWLOCATION, true);
    curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($curl, CURLOPT_TIMEOUT, 15);
    curl_setopt($curl, CURLOPT_SSL_VERIFYHOST, false);
    curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, false);
    curl_setopt($curl, CURLOPT_USERAGENT, $_SERVER['HTTP_USER_AGENT']);
    $response = curl_exec($curl);
    curl_close($curl);
    if (!empty($response)) {
        return self::_parse($response);
    } else {
        return false;
    }
}

static private function _parse($HTML) {
    $old_libxml_error = libxml_use_internal_errors(true);
    $doc = new DOMDocument();
    $doc->loadHTML($HTML);

    libxml_use_internal_errors($old_libxml_error);
    $tags = $doc->getElementsByTagName('meta');
    if (!$tags || $tags->length === 0) {
        return false;
    }
    $page = new self();
    $nonOgDescription = null;

    foreach ($tags AS $tag) {
        if ($tag->hasAttribute('property') &&
            strpos($tag->getAttribute('property'), 'og:') === 0) {
            $key = strtr(substr($tag->getAttribute('property'), 3), '-', '_');
            $page->_values[$key] = $tag->getAttribute('content');
        }

        //Added this if loop to retrieve description values from sites like the New York Times who have malformed it. 
        if ($tag ->hasAttribute('value') && $tag->hasAttribute('property') &&
            strpos($tag->getAttribute('property'), 'og:') === 0) {
            $key = strtr(substr($tag->getAttribute('property'), 3), '-', '_');
            $page->_values[$key] = $tag->getAttribute('value');
        }
        //Based on modifications at https://github.com/bashofmann/opengraph/blob/master/src/OpenGraph/OpenGraph.php
        if ($tag->hasAttribute('name') && $tag->getAttribute('name') === 'description') {
            $nonOgDescription = $tag->getAttribute('content');
        }

    }
    //Based on modifications at https://github.com/bashofmann/opengraph/blob/master/src/OpenGraph/OpenGraph.php
    if (!isset($page->_values['title'])) {
        $titles = $doc->getElementsByTagName('title');
        if ($titles->length > 0) {
            $page->_values['title'] = $titles->item(0)->textContent;
        }
    }
    if (!isset($page->_values['description']) && $nonOgDescription) {
        $page->_values['description'] = $nonOgDescription;
    }
    //Fallback to use image_src if ogp::image isn't set.
    if (!isset($page->values['image'])) {
        $domxpath = new DOMXPath($doc);
        $elements = $domxpath->query("//link[@rel='image_src']");
        if ($elements->length > 0) {
            $domattr = $elements->item(0)->attributes->getNamedItem('href');
            if ($domattr) {
                $page->_values['image'] = $domattr->value;
                $page->_values['image_src'] = $domattr->value;
            }
        }
    }
    if (empty($page->_values)) { return false; }

    return $page;
}

public function __get($key) {
    if (array_key_exists($key, $this->_values)) {
        return $this->_values[$key];
    }

    if ($key === 'schema') {
        foreach (self::$TYPES AS $schema => $types) {
            if (array_search($this->_values['type'], $types)) {
                return $schema;
            }
        }
    }
}

public function keys() {
    return array_keys($this->_values);
}

public function __isset($key) {
    return array_key_exists($key, $this->_values);
}

public function hasLocation() {
    if (array_key_exists('latitude', $this->_values) && array_key_exists('longitude', $this->_values)) {
        return true;
    }

    $address_keys = array('street_address', 'locality', 'region', 'postal_code', 'country_name');
    $valid_address = true;
    foreach ($address_keys AS $key) {
        $valid_address = ($valid_address && array_key_exists($key, $this->_values));
    }
    return $valid_address;
}

private $_position = 0;
public function rewind() { reset($this->_values); $this->_position = 0; }
public function current() { return current($this->_values); }
public function key() { return key($this->_values); }
public function next() { next($this->_values); ++$this->_position; }
public function valid() { return $this->_position < sizeof($this->_values); }}

Implementation:

require_once('OpenGraph.php');
$graph = OpenGraph::fetch('http://www.google.com');
echo $graph->keys('description');

I actually got this code from a github here: https://github.com/scottmac/opengraph

Answer 1

The keys() method returns an array, and it takes no arguments. What you are doing when you use

echo $graph->keys('description')

is calling that method with 'description' as an argument, which it will ignore, then echoing the entire array. When you use echo on an array, it will just print Array like you are seeing. Because of the __get() magic method , I think you should be able to just use

echo $graph->description