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How to extract a value of an HTML input tag using PHP

Answer 1

A:

Post the form to a php page. The value you want will be in $_POST['id'].

no 2010-07-14 19:17:22

Answer 2

A:

What do you mean regex isn't popular? I for one love regular expressions.

Anyway, what you want is something like:

$contents = file_get_contents('/path/to/file.html');
preg_match('/value="(\w+)"/',$contents,$result);

Josiah 2010-07-14 19:18:52

Everyone loves them... just NOT FOR HTML PARSING. See http://stackoverflow.com/questions/1732348/regex-match-open-tags-except-xhtml-self-contained-tags/1732454#1732454 for a bit of context regarding this and SO!

Alex JL 2010-07-14 19:23:19

Hahha I agree, regex is horrid for parsing HTML. However, for the question at hand, regex is a perfectly valid solution, though definitely not the only solution.

Josiah 2010-07-14 19:27:54

What if there is other inputs in the HTML that have a value attribute? What if the attribute is not written precisely `value="foo"`, but `Value = "foo"`. What if the HTML contains this very comment?

Gordon 2010-07-14 19:55:08

All of those can be solved in regex. The solution simply becomes less and less elegant. I'm not in any way advocating regex as a solution for parsing anything as loosely formed as HTML. The question asked for a regex in PHP for a very specific, closed-ended situation.

Josiah 2010-07-14 22:21:27

Agreed, your regex does work and it fits the question, but the best thing to do is to advise the asker not to use regexes for this and to instead propose a solution that incorporates a better practice.

Alex JL 2010-07-17 20:12:42

Answer 3

+3 A:

If you want to extract some data from some HTML string, the best solution is often to work with the DOMDocument class, that can load HTML to a DOM Tree.

Then, you can use any DOM-related way of extracting data, like, for example, XPath queries.

Here, you could use something like this :

$html = <<<HTML
    <form action="blabla.php" method=post>

    <input type="text" name="campaign">  
    <input type="text" name="id" value="this-is-what-i-am-trying-to-extract">

    </form>
HTML;


$dom = new DOMDocument();
$dom->loadHTML($html);

$xpath = new DOMXPath($dom);

$tags = $xpath->query('//input[@name="id"]');
foreach ($tags as $tag) {
    var_dump(trim($tag->getAttribute('value')));
}

And you'd get :

string 'this-is-what-i-am-trying-to-extract' (length=35)

Pascal MARTIN 2010-07-14 19:19:21

Try `echo $xPath->evaluate('string(//input[@name="id"]/@value)');`

Gordon 2010-07-14 19:41:53

Answer 4

A:

$html=new DOMDocument();
$html->loadHTML('<form action="blabla.php" method=post>
    <input type="text" name="campaign">  
    <input type="text" name="id" value="this-is-what-i-am-trying-to-extract">
    </form>');

$els=$html->getelementsbytagname('input');

foreach($els as $inp)
  {
  $name=$inp->getAttribute('name');
  if($name=='id'){
    $what_you_are_trying_to_extract=$inp->getAttribute('value');
    break;
    }
  }

echo $what_you_are_trying_to_extract;
//produces: this-is-what-i-am-trying-to-extract

Alex JL 2010-07-14 19:22:20

Will trigger *Strict Standards: Non-static method DOMDocument::loadHTML() should not be called statically*

Gordon 2010-07-14 19:41:05

Yeah, I suppose... but it works. Might as well go with the preferred style.

Alex JL 2010-07-14 21:57:59

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How to extract a value of an HTML input tag using PHP

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