html发布到php生成XML文件？

I'm having hard time to do a php post to a XML data here is my form:

<form action="../xml/data.php" method"post">
  <p>Name</p>
  <input name='name' required><br>
  <p>ID</p>
  <input name"id" required>
  <input type='submit' value ="submit" name="submit">
</form>

here is my PHP code:

<?php
$s_id=$_POST['id'];
$s_name=$_POST['name'];
$xml = new DOMDocument("1.0");
$student = $xml -> createElement("student");
$xml -> appendChild($student);

$id_value = $xml ->createTextNode("$s_id");
$id -> appendChild($id_value);
$name = $xml -> createElement("name");
$student -> appendChild($name);
$name_value=$xml->createTextNode("$s_name");
$name->appendChild($name_value);
$xml ->formatOutput = true;

$xml -> save("mydata.xml");
?>

But it doesn't make the mydata.xml file and not working :s not sure what i'm doing wrong here

You're missing an = in your form tag:

<form action="../xml/data.php" method"post">

should be

<form action="../xml/data.php" method="post">

And also here

<input name"id" required>

should be

<input name="id" required>

@PHPglue is correct too - $id -> appendChild($id_value); should presumably be $student -> appendChild($id_value);.

You are missing a few equals signs in your form code:

<form action="../xml/data.php" method"post">

and

<input name"id" required>

should be:

<form action="../xml/data.php" method="post">

and

<input name="id" required>