I'm trying to figure out how parse an html page to get a forms action value, the labels within the form tab as well as the input field names. I took at look at php.net Domdocument and it tells me to get a childnode but all that does is give me errors that it doesnt exist. I also tried doing print_r of the variable holding the html content and all that shows me is length=1. Can someone show me a few samples that i can use because php.net is confusing to follow.
<?php
$content = "some-html-source";
$content = preg_replace("/&(?!(?:apos|quot|[gl]t|amp);|#)/", '&', $content);
$dom = new DOMDocument;
$dom->preserveWhiteSpace = FALSE;
$dom->loadHTML($content);
$form = $dom->getElementsByTagName('form');
print_r($form);
I suggest using DomXPath instead of getElementsByTagName because it allows you to select attribute values directly and returns a DOMNodeList object just like getElementsByTagName. The # in #action indicates that we're selecting by attribute.
$doc = new DOMDocument();
$doc->loadHTML($content);
$xpath = new DomXPath($doc);
$action = $xpath->query('//form/#action')->item(0);
var_dump($action);
Similarly, to get the first input
$action = $xpath->query('//form/input')->item(0);
To get all input fields
for($i=0;$i<$xpath->query('//form/input')->length;$i++) {
$label = $xpath->query('//form/input')->item($i);
var_dump($label);
}
If you're not familiar with XPath, I recommend viewing these examples.
Related
I am using domDocument hoping to parse this little html code. I am looking for a specific span tag with a specific id.
<span id="CPHCenter_lblOperandName">Hello world</span>
My code:
$dom = new domDocument;
#$dom->loadHTML($html); // the # is to silence errors and misconfigures of HTML
$dom->preserveWhiteSpace = false;
$nodes = $dom->getElementsByTagName('//span[#id="CPHCenter_lblOperandName"');
foreach($nodes as $node){
echo $node->nodeValue;
}
But For some reason I think something is wrong with either the code or the html (how can I tell?):
When I count nodes with echo count($nodes); the result is always 1
I get nothing outputted in the nodes loop
How can I learn the syntax of these complex queries?
What did I do wrong?
You can use simple getElementById:
$dom->getElementById('CPHCenter_lblOperandName')->nodeValue
or in selector way:
$selector = new DOMXPath($dom);
$list = $selector->query('/html/body//span[#id="CPHCenter_lblOperandName"]');
echo($list->item(0)->nodeValue);
//or
foreach($list as $span) {
$text = $span->nodeValue;
}
Your four part question gets an answer in three parts:
getElementsByTagName does not take an XPath expression, you need to give it a tag name;
Nothing is output because no tag would ever match the tagname you provided (see #1);
It looks like what you want is XPath, which means you need to create an XPath object - see the PHP docs for more;
Also, a better method of controlling the libxml errors is to use libxml_use_internal_errors(true) (rather than the '#' operator, which will also hide other, more legitimate errors). That would leave you with code that looks something like this:
<?php
libxml_use_internal_errors(true);
$dom = new DOMDocument();
$dom->loadHTML($html);
$xpath = new DOMXPath($dom);
foreach($xpath->query("//span[#id='CPHCenter_lblOperandName']") as $node) {
echo $node->textContent;
}
I have the following script snippet. Originally I did not realize to use getElementById that I needed to include createDocumentType, but now I get the error listed above. What am I doing wrong here? Thanks in advance!
...
$result = curl_exec($ch); //contains some webpage i am grabbing remotely
$dom = new DOMDocument();
$dom->createDocumentType('html', '-//W3C//DTD HTML 4.01 Transitional//EN', 'http://www.w3.org/TR/html4/loose.dtd');
$elements = $dom->loadHTML($result);
$e = $elements->getElementById('1');
...
Edit: Additional note, I verified the DOM is correct on the remote page.
DOMDocument does not have a method named createDocumentType, as you can see in the Manual. The method belongs to the DOMImplemetation class. It is used like this (taken from the manual):
// Creates an instance of the DOMImplementation class
$imp = new DOMImplementation;
// Creates a DOMDocumentType instance
$dtd = $imp->createDocumentType('graph', '', 'graph.dtd');
// Creates a DOMDocument instance
$dom = $imp->createDocument("", "", $dtd);
Since you want to load HTML into the document, you don't need to specify a document type, since it is determined from the imported HTML. You just have to have some id attributes, or a DTD that identifies an other attribute as an id. This is part of the HTML file, not the parsing PHP code.
$dom = new DOMDocument();
$dom->loadHTML($result);
$element = $dom->getElementById('my_id');
will do the job.
I am parsing an HTML page with DOM and XPath in PHP.
I have to fetch a nested <Table...></table> from the HTML.
I have defined a query using FirePath in the browser which is pointing to
html/body/table[2]/tbody/tr/td[2]/table[2]/tbody/tr/td/table
When I run the code it says DOMNodeList is fetched having length 0. My objective is to spout out the queried <Table> as a string. This is an HTML scraping script in PHP.
Below is the function. Please help me how can I extract the required <table>
$pageUrl = "http://www.boc.cn/sourcedb/whpj/enindex.html";
getExchangeRateTable($pageUrl);
function getExchangeRateTable($url){
$htmlTable = "";
$xPathTable = nulll;
$xPathQuery1 = "html/body/table[2]/tbody/tr/td[2]/table[2]/tbody/tr/td/table";
if(strlen($url)==0){die('Argument exception: method call [getExchangeRateTable] expects a string of URL!');}
// initialize objects
$page = tidyit($url);
$dom = new DOMDocument();
$dom->loadHTML($page);
$xpath = new DOMXPath($dom);
// $elements is sppearing as DOMNodeList
$elements = $xpath->query($xPathQuery1);
// print_r($elements);
foreach($elements as $e){
$e->firstChild->nodeValue;
}
}
have you try like this
$dom = new domDocument;
$dom->loadHTML($tes);
$dom->preserveWhiteSpace = false;
$tables = $dom->getElementsByTagName("table");
$rows = $tables->item(0)->getElementsByTagName("tr");
print_r($rows);
Remove the tbody's from your XPath query - they are in most cases inserted by your browser, as is with the page you are trying to scrape.
/html/body/table[2]/tr/td[2]/table[2]/tr/td/table
This will most likely work.
However, its probaly more safe to use a different XPath. Following XPath will select the first th based on it's textual content, then select the tr's parent - a tbody or table:
//th[contains(text(),'Currency Name')]/parent::tr/parent::*
The xpath query should be with a leading / like :-
/html/...
I am trying to parse all script src link values, but I get an empty array.
$dom = new DOMDocument();
$file = #$dom->loadHTML($remote);
$xpath = new DOMXpath($dom);
$link = $xpath->query('//script[contains(#src, "pcode")]');
$return = array();
foreach($link as $links) {
$return[] = $links->nodeValue;
}
Your XPATH query looks valid, should grab every <script> with attribute src containing pcode.
If it's returning an empty array, there's a few things to check:
Make sure the DOM document and loading, and there are not errors when loading it into XPATH. It could be possible that the suppressed DOM->load is giving an error or warning. If you query elsewhere and it works, then ignore this.
Make sure the tags in your document are case-matching.
Try
$link = $xpath->query("//script[contains(#src, 'pcode')]");
Seems silly, just switching quote marks, but you never know.
Be sure to check namespaces. If your HTML contains a declaration like this
<html xmlns="http://www.w3.org/1999/xhtml">
You'll need to register the namespace with the document
$xp = new domxpath( $xml);
$xp->registerNamespace('html', 'http://www.w3.org/1999/xhtml' );
And Look for elements like this
$elements = $xp->query( "//html:script", $xml );
Namespaces, because paranoia breeds confidence.
A little new to PHP parsing here, but I can't seem to get PHP's DOMDocument to return what is clearly an identifiable node. The HTML loaded will come from the 'net so can't necessarily guarantee XML compliance, but I try the following:
<?php
header("Content-Type: text/plain");
$html = '<html><body>Hello <b id="bid">World</b>.</body></html>';
$dom = new DOMDocument;
$dom->preserveWhiteSpace = false;
$dom->validateOnParse = true;
/*** load the html into the object ***/
$dom->loadHTML($html);
var_dump($dom);
$belement = $dom->getElementById("bid");
var_dump($belement);
?>
Though I receive no error, I only receive the following as output:
object(DOMDocument)#1 (0) {
}
NULL
Should I not be able to look up the <b> tag as it does indeed have an id?
The Manual explains why:
For this function to work, you will need either to set some ID attributes with DOMElement->setIdAttribute() or a DTD which defines an attribute to be of type ID. In the later case, you will need to validate your document with DOMDocument->validate() or DOMDocument->validateOnParse before using this function.
By all means, go for valid HTML & provide a DTD.
Quick fixes:
Call $dom->validate(); and put up with the errors (or fix them), afterwards you can use $dom->getElementById(), regardless of the errors for some reason.
Use XPath if you don't feel like validing: $x = new DOMXPath($dom); $el = $x->query("//*[#id='bid']")->item(0);
Come to think of it: if you just set validateOnParse to true before loading the HTML, if would also work ;P
.
$dom = new DOMDocument();
$html ='<html>
<body>Hello <b id="bid">World</b>.</body>
</html>';
$dom->validateOnParse = true; //<!-- this first
$dom->loadHTML($html); //'cause 'load' == 'parse
$dom->preserveWhiteSpace = false;
$belement = $dom->getElementById("bid");
echo $belement->nodeValue;
Outputs 'World' here.
Well, you should check if $dom->loadHTML($html); returns true (success) and I would try
var_dump($belement->nodeValue);
for output to get a clue what might be wrong.
EDIT:
http://www.php-editors.com/php_manual/function.domdocument-get-element-by-id.html - it seems that DOMDocument uses XPath internally.
Example:
$xpath = xpath_new_context($dom);
var_dump(xpath_eval_expression($xpath, "//*[#ID = 'YOURIDGOESHERE']"));