使用PHP解析XML Feed以查找是否存在特定数据

Question

I need to check if Team1 exists in the XML feed. If Team1 appears twice in the XML feed, I need to output only the first instance. So far I can only output both instances. How do I accomplish this?

$str = <<<'XML'
<DATAS>
    <DATA>
        <VISITOR>Team6</VISITOR>
        <HOME>Team7</HOME>
    </DATA>
    <DATA>
        <VISITOR>Team1</VISITOR>
        <HOME>Team2</HOME>
    </DATA>
    <DATA>
        <VISITOR>Team3</VISITOR>
        <HOME>Team1</HOME>
    </DATA>
    <DATA>
        <VISITOR>Team4</VISITOR>
        <HOME>Team5</HOME>
    </DATA>
</DATAS>    
XML;


$data = new SimpleXMLElement($str);

$found = false;

foreach ($data->DATA as $item) {
    $teamh = $item->HOME;
    $teamv = $item->VISITOR;


    if ($teamh == 'Team1' || $teamv == 'Team1') { 
        $found = true;

    echo 'Home Team: ' . $data->DATA->HOME . "
";
    echo 'Away Team: ' . $data->DATA->VISITOR . "
";
   }

}

Answer 1

Use XPath. Selecting nodes on a DOM tree is easy with it. (SimpleXML uses a DOM in the background). Here are to methods for it SimpleXMLElement::xpath() and DOMXpath::evaluate().

Select all event data:
/DATAS/DATA

Only if VISITOR or HOME is "Team1":
/DATAS/DATA[VISITOR='Team1' or HOME='Team1']

Count them:
count(/DATAS/DATA[VISITOR='Team1' or HOME='Team1'])

Limit to the first found node:
/DATAS/DATA[VISITOR='Team1' or HOME='Team1'][1]

SimpleXMLElement::xpath() always returns an array of SimpleXMLElement objects. So it can not directly execute the count(...) Xpath expression.

You can of course use the PHP function count() on the return value.

count($datas->xpath("/DATAS/DATA[VISITOR='Team1' or HOME='Team1']"));

If you only want to output the first event data for a team if it exists you will not need the count. Limiting the result in XPath will return a list/array with a single element or an empty list.

SimpleXML Example

$datas = simplexml_load_string($str);

$eventCount = count($datas->xpath("/DATAS/DATA[VISITOR='Team1' or HOME='Team1']"));
echo "Team1 is included $eventCount time(s) in the feed.
";

$events = $datas->xpath("/DATAS/DATA[VISITOR='Team1' or HOME='Team1'][1]");
foreach ($events as $event) {
  echo "Visitor: {$event->VISITOR}, Home: {$event->HOME}
"; 
}

DOM Example

$dom = new DOMDocument();
$dom->loadXml($str);
$xpath = new DOMXPath($dom);

$eventCount = $xpath->evaluate("count(/DATAS/DATA[VISITOR='Team1' or HOME='Team1'])");
echo "Team1 is included $eventCount time(s) in the feed.
";

$events = $xpath->evaluate("/DATAS/DATA[VISITOR='Team1' or HOME='Team1'][1]");
foreach ($events as $event) {
  $visitor = $xpath->evaluate('string(VISITOR)', $event);
  $home = $xpath->evaluate('string(HOME)', $event);
  echo "Visitor: $visitor, Home: $home
"; 
}