如何在php中使用属性遍历对象值

Question

I am having my data in xml. And I want to traverse it. When I print var_dump($video_xml->playlist->video->labels->label) the output is

object(SimpleXMLElement)#41 (4) {
  ["@attributes"]=>
  array(11) {
    ["id"]=>
    string(1) "0"
    ["start"]=>
    string(1) "0"
    ["end"]=>
    string(17) "8.639527777777777"
    ["pos"]=>
    string(12) "124,66,95,45"
    ["marker"]=>
    string(5) "false"
    ["href"]=>
    string(0) ""
    ["bold"]=>
    string(5) "false"
    ["italic"]=>
    string(5) "false"
    ["color"]=>
    string(17) "rgb(62, 201, 106)"
    ["face"]=>
    string(7) "Verdana"
    ["size"]=>
    string(2) "24"
  }
  [0]=>
  string(8) "Label1fg"
  [1]=>
  string(6) "Label0"
  [2]=>
  string(6) "Label0"
}

however when I print each object in a foreach loop it gives

object(SimpleXMLElement)#56 (1) {
  ["@attributes"]=>
  array(11) {
    ["id"]=>
    string(1) "0"
    ["start"]=>
    string(1) "0"
    ["end"]=>
    string(17) "8.639527777777777"
    ["pos"]=>
    string(12) "124,66,95,45"
    ["marker"]=>
    string(5) "false"
    ["href"]=>
    string(0) ""
    ["bold"]=>
    string(5) "false"
    ["italic"]=>
    string(5) "false"
    ["color"]=>
    string(17) "rgb(62, 201, 106)"
    ["face"]=>
    string(7) "Verdana"
    ["size"]=>
    string(2) "24"
  }
}

I want to print object value like Label0. How can I get it. I am using following code to print label

foreach($video_xml->playlist->video->labels->label as $label){
        var_dump($label);
    }

and I am expecting output as: string(8) "Label1fg" string(6) "Label0" string(6) "Label0"

Answer 1

A SimpleXMLElement object behaves like an object, but is actually a system RESOURCE, (specifically a libxml resource). All its properties are also SimpleXMLElement objects. You need to convert each leaf node to the expected type to get primitive values (strings, f.e.).

foreach ($video_xml->playlist->video->labels->label as $label) {
    var_dump((string)$label);
}

should print what you want.

---

If the nodes of your XML document do not have attributes and you do only simple operations with it (get data from some nodes), a simpler way to work with it is to use json_encode()/json_decode() to convert it to an multi-level array:

// TRUE as the second argument to json_decode() to get back arrays, not objects
$video_data = json_decode(json_encode($video_xml), TRUE));

foreach ($video_data['playlist']['video']['labels']['label'] as $label) {
    var_dump($label);
}

If you don't pass TRUE as the second argument to json_decode() it returns an object (stdClass) and you can use the existing code to navigate through it.

---

If you have to operate on the XML document structure, in my opinion it's easier to work with DOMElement and the other DOM classes.