Unique Object Identifier

[jasonlfunk]

I am using SimpleXML to analyze an XML file and output it as an HTML form. I want to give each form a unique name that was generated from the SimpleXML object. I tried hashing each object, but it always gave me the same hash. Here is an example of what I mean:

 

$xml = simplexml_load_file("calendar.xml");
foreach($xml->event as $event)
{
        $hash = MD5($event);
        echo "<form name=$hash>";
          ... fill in the rest of the form
        echo "</form>

}

 

The XML file looks like this:

 

<events startDate="2007-01-01" endDate="2007-12-31">

        <event title="Test Event 1" description="once on 10 february" startDate="2007-02-10 17:30:00" endDate="2007-02-10 19:30:00" allDay="0" eventType="once" />
        <event title="Test Event 2" description="once on 1 march" startDate="2007-03-01 09:30:00" endDate="2007-03-01 11:00:00" allDay="0" eventType="once" />
</events>   

 

So the script would output a page with 2 forms and I want them to have unique names, but the forms are ending up with the same name. Ideas on how to do this? Thanks

[akitchin]

assuming $xml->event is an array of arrays, your issue is that you're trying to hash an array (whereas the function expects a string).  choose some string from the array to hash:

 

$hash = MD5($event['title']);

[corbin]

You could try

 

foreach($xml->event as $k => $event)
{
        $hash = MD5($k . $event);
        echo "<form name=$hash>";
          ... fill in the rest of the form
        echo "</form>

}

 

That way it will throw the unique key from the event array in there aswell ;p.

[448191]

spl_object_hash() will always give you the same unique hash, but only within a single run.

 

If you need an I'd that is constant across requests, why don't you simply introduce a name attribute into the root element of each XML file?

 

I've written something similar very recently (no support for selectboxes or radio/checkbox groups yet though):

 

Example Form file:

<?xml version="1.0"?>
<!DOCTYPE form PUBLIC "Backbone Form Map" "form.dtd">
<form name="login" action="/User/DoLogin" method="post" feedback="1">
<input name="user" type="text" value="" required="1" maxlen="20" description="Gebruiker"/>
<input name="pass" type="password" required="1" maxlen="20" description="Wachtwoord" />
<input name="submit" type="submit" value="Login" required="0"/>
</form>

 

DTD:

<!ELEMENT form (input+)>
<!ATTLIST form
name CDATA #REQUIRED
action CDATA #REQUIRED
method (post|get) #IMPLIED
feedback (0|1) #IMPLIED
>
<!ELEMENT input EMPTY>
<!ATTLIST input
name ID #REQUIRED
type (text|password|textarea|checkbox|radio|select|submit|reset) #REQUIRED
value CDATA #IMPLIED
required (0|1) #IMPLIED
maxlen CDATA #IMPLIED
minlen CDATA #IMPLIED
pregmatch CDATA #IMPLIED
description CDATA #IMPLIED
>

 

<?php
class Backbone_Form_DataMapper_Xml extends Backbone_Data_Mapper_Abstract {

private static $path;
private static $ext;

public static function init($path, $ext = '.form'){
	self::$path = $path;
	self::$ext = $ext;
}

public function find($name){

	$formMap = new DOMDocument();
	$formMap->validateOnParse = true;
	$file = self::$path.DIRECTORY_SEPARATOR.$name.self::$ext;
	if(!file_exists($file)){
		throw new Backbone_Form_DataMapper_Xml_Exception('Unable to load form map, file does not exist ("'.$file.'")');
	}
	$formMap->load($file);

	$formNode = $formMap->documentElement;
	if($formNode->getAttribute('name') != $name){
		throw new Backbone_Form_DataMapper_Xml_Exception('Xml- filename mismatch!');
	}
	$formObject = new Backbone_Form_Object(
		$formNode->getAttribute('name'),
		$formNode->getAttribute('action'),
		$formNode->hasAttribute('method')? $formNode->getAttribute('method') : 'post',
		$formNode->hasAttribute('feedback')? $formNode->getAttribute('feedback') : true
	);

	foreach($formMap->getElementsByTagName('input') as $input){
		$formObject->addElement(new Backbone_Form_Element(
			$input->getAttribute('name'),
			$input->getAttribute('type'),
			$input->hasAttribute('value')? $input->getAttribute('value') : null,
			$input->hasAttribute('required')? $input->getAttribute('required') : true,
			$input->hasAttribute('maxlen')? $input->getAttribute('maxlen') : null,
			$input->hasAttribute('minlen')? $input->getAttribute('minlen') : null,
			$input->hasAttribute('pregmatch')? $input->getAttribute('pregmatch') : null,
			$input->hasAttribute('description')? $input->getAttribute('description') : null
		));
	}
	return $formObject;
}
function delete(Backbone_DomainObject $object){}
function create(Backbone_DomainObject $object){}
function update(Backbone_DomainObject $object){}
function isStored($id){}
}
?>

[keeB]

Im going to hijack this thread and say, 448191, you should be using an Abstract Factory pattern (if you aren't already) with your approach

 

Backbone_Form_DataMapper <- Interface

Backbone_Data_Mapper_Abstract <- Factory

Backbone_Form_DataMapper_Xml <- Concrete Product.

 

So, I could make, say, Backbone_Form_DataMapper_CSV and no one would care

 

Just my 2c

[448191]

In this case, there's no justification for Abstract Factory. Data Mappers are managed and created by a data controller (Unit of Work Controller/ad hoc Service Layer), and instantiating them requires no arguments.

 

		/**
 * Fetches Data Mapper from stack, creating one if required
 *
 * @param string|Backbone_Data_Domain_Object $domain
 * @return Backbone_Data_Mapper_Abstract
 */
public function getDataMapper($domain){
	if($domain instanceof Backbone_Data_Domain_Object){
		$mapperClass = get_class($domain).$this->mapperSuffix;
	}
		else {
		$mapperClass = $domain.$this->mapperSuffix;
	}
	if(!class_exists($mapperClass, true)) {
		throw new Backbone_Data_Controller_Exception('Mapper class "'.$domain.'" does not exist.');	

	}
	if(!isset($this->dataMappers[$mapperClass])){
		$this->dataMappers[$mapperClass] = new $mapperClass;
	}
	return $this->dataMappers[$mapperClass];
}

 

And yes, that would mean I could simply create Backbone_Form_DataMapper_CSV, without any other required changes (except for a configuration flag). At some point I might introduce an Abstract Factory, but right now I'm thinking YAGNI.

[keeB]

Very cool. I knew you had probably thought it through, but wanted to make sure