Programming Forums > Web Development and Design > PHP

niteice · Jun 23rd, 2006, 11:06 AM

I have an XML document describing a section of a site I'm coding. I'm already using it to generate a page, but now I need to also use it to generate a navigation bar. The documents is structured like so:

(Toggle Plain Text)

<downloads>
	<category name="blah">
		<section name="blah">
			<file name="blah" size="somenumber" link="someurl" />
		</section>
	</category>
	<category name="blah2>
	...etc

The code generates a downloads page using <section> and <file>. Now I'm generating a navigation bar using <category>. Unfortunately, there always seems to be an off-by-one error when I'm looping through the data. My XML parser is SimpleXML. The code I have currently is:

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function generateNav()
{
	$data = simplexml_load_file("data/downloads.xml");
	$out = "";

	for($i = 1; $i <= count($data->category); $i++)
	{
		$out .= "<a href=\"downloads.php?c=$i\">".$data->category[$i]["name"]."</a> ";
	}

	return $out;
}

But it will, for some reason, only show the second category link. I've tried various other combinations, which produce weird numbers or just don't display anything at all. Inexplicably, count($data->category) seems to return either 1 or nothing., even though there's 4 <category> tags in the file.

DaWei · Jun 23rd, 2006, 11:36 AM

Consider using print_r to see what you get for $data and its constituents. Information is key to debugging. Information is there for the viewing, if you look.

niteice · Jun 23rd, 2006, 12:18 PM

Hmm...print_r shows the document tree the way I expected it to- category[0] through category[3]. Yet count($data->category) still says there's 1 element, when there should be 4. Is there a better way to find the number of elements in the array?

I also tried foreach(). The problem with that is that I need the array index to correctly generate the navigation link.

DaWei · Jun 23rd, 2006, 12:22 PM

Can you post here what you get with the print_r, as well as the class definition for data?

niteice · Jun 23rd, 2006, 12:35 PM

$data isn't a class per se - instead, SimpleXML parses the XML into a structure that can be sort of read like a class. First attachment is the print_r output, second is some sample data structured the same way.

DaWei · Jun 23rd, 2006, 2:50 PM

First off, arrays are based at 0. Your loop should not begin at 1.

Okay, here is my take on the rest, and my fix. Please understand that I am not a PHP expert. While $data->category is an array, I believe it is being treated, first, as an object. Count will not work on objects, but will return a 1. (There is a method of making objects countable, but I didn't delve into that.) In order to get around the problem, I used foreach to copy 'category' into another array. I then got the count from that array, and produced the links. Here is my code:

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<?php
function generateNav()
{
	$data = simplexml_load_file("data.xml");
	foreach ($data->category as $thangy) $myArray [] = $thangy;
	$out = "";
	for($i = 0; $i < count ($myArray); $i++)
		$out .= "<a href=\"downloads.php?c=$i\">".$data->category[$i]["name"]."</a><br/> ";
	return $out;
}
echo generateNav ();
?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
<title>Huh!</title>
</head>
<body>

</body>
</html>

Here is my output:

Quote:

Originally Posted by Output

Some category
Some Other Category
Yet Another Category
God Damn How Many Categories Are There

niteice · Jun 23rd, 2006, 3:05 PM

For some reason your original foreach didn't work, so it becomes:

(Toggle Plain Text)

function generateNav()
{
	$data = simplexml_load_file("data/downloads.xml");
	$out = "";
	$i = 0;

	foreach ($data->category as $cat)
	{
		$categories[$i++] = $cat;
	}

	for($j = 0; $j < count ($categories); $j++)
	{
		$k = $j + 1;
		$out .= "<a href=\"downloads.php?c=$k\">".$data->category[$j]["name"]."</a><br/> ";
	}

	return $out;
}

I also needed the URLs to start at 1 instead of 0 because of how the rest of the code works, hence $k. At any rate, it now works how I wanted, thanks for the help.

DaWei · Jun 23rd, 2006, 3:18 PM

Worked for me. That's how it produced the output. You can invoke the page (code shown above) here. Perhaps you didn't renew your right to use the variable, $thangy (tm DaWei).

niteice · Jun 23rd, 2006, 3:30 PM

Aha, my browser somehow cut out the [] after $myArray.

DaWei · Jun 23rd, 2006, 5:00 PM

Here's a way that doesn't waste time copying the array:

(Toggle Plain Text)

   $i = 0;
   foreach ($data->category as $cat) $i++;
   for ($j = 0; $j < $i; $j++)
   {
      blah blah do da stuff...

Jun 23rd, 2006, 11:06 AM	#1
niteice Programmer Join Date: Aug 2005 Posts: 98 Rep Power: 4	SimpleXML issues I have an XML document describing a section of a site I'm coding. I'm already using it to generate a page, but now I need to also use it to generate a navigation bar. The documents is structured like so: (Toggle Plain Text) <downloads> <category name="blah"> <section name="blah"> <file name="blah" size="somenumber" link="someurl" /> </section> </category> <category name="blah2> ...etc <downloads> <category name="blah"> <section name="blah"> <file name="blah" size="somenumber" link="someurl" /> </section> </category> <category name="blah2> ...etc The code generates a downloads page using <section> and <file>. Now I'm generating a navigation bar using <category>. Unfortunately, there always seems to be an off-by-one error when I'm looping through the data. My XML parser is SimpleXML. The code I have currently is: (Toggle Plain Text) function generateNav() { $data = simplexml_load_file("data/downloads.xml"); $out = ""; for($i = 1; $i <= count($data->category); $i++) { $out .= "<a href=\"downloads.php?c=$i\">".$data->category[$i]["name"]."</a> "; } return $out; } function generateNav() { $data = simplexml_load_file("data/downloads.xml"); $out = ""; for($i = 1; $i <= count($data->category); $i++) { $out .= "<a href=\"downloads.php?c=$i\">".$data->category[$i]["name"]."</a> "; } return $out; } But it will, for some reason, only show the second category link. I've tried various other combinations, which produce weird numbers or just don't display anything at all. Inexplicably, count($data->category) seems to return either 1 or nothing., even though there's 4 <category> tags in the file.

Jun 23rd, 2006, 11:36 AM	#2
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	Consider using print_r to see what you get for $data and its constituents. Information is key to debugging. Information is there for the viewing, if you look. __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

Jun 23rd, 2006, 12:22 PM	#4
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	Can you post here what you get with the print_r, as well as the class definition for data? __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

Jun 23rd, 2006, 3:05 PM	#7
niteice Programmer Join Date: Aug 2005 Posts: 98 Rep Power: 4	For some reason your original foreach didn't work, so it becomes: (Toggle Plain Text) function generateNav() { $data = simplexml_load_file("data/downloads.xml"); $out = ""; $i = 0; foreach ($data->category as $cat) { $categories[$i++] = $cat; } for($j = 0; $j < count ($categories); $j++) { $k = $j + 1; $out .= "<a href=\"downloads.php?c=$k\">".$data->category[$j]["name"]."</a><br/> "; } return $out; } function generateNav() { $data = simplexml_load_file("data/downloads.xml"); $out = ""; $i = 0; foreach ($data->category as $cat) { $categories[$i++] = $cat; } for($j = 0; $j < count ($categories); $j++) { $k = $j + 1; $out .= "<a href=\"downloads.php?c=$k\">".$data->category[$j]["name"]."</a><br/> "; } return $out; } I also needed the URLs to start at 1 instead of 0 because of how the rest of the code works, hence $k. At any rate, it now works how I wanted, thanks for the help.

Jun 23rd, 2006, 3:18 PM	#8
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	Worked for me. That's how it produced the output. You can invoke the page (code shown above) here. Perhaps you didn't renew your right to use the variable, $thangy (tm DaWei). __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

Jun 23rd, 2006, 12:18 PM	#3
niteice Programmer Join Date: Aug 2005 Posts: 98 Rep Power: 4	Hmm...print_r shows the document tree the way I expected it to- category[0] through category[3]. Yet count($data->category) still says there's 1 element, when there should be 4. Is there a better way to find the number of elements in the array? I also tried foreach(). The problem with that is that I need the array index to correctly generate the navigation link.

Jun 23rd, 2006, 3:30 PM	#9
niteice Programmer Join Date: Aug 2005 Posts: 98 Rep Power: 4	Aha, my browser somehow cut out the [] after $myArray.

Jun 23rd, 2006, 5:00 PM	#10
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	Here's a way that doesn't waste time copying the array: (Toggle Plain Text) $i = 0; foreach ($data->category as $cat) $i++; for ($j = 0; $j < $i; $j++) { blah blah do da stuff... $i = 0; foreach ($data->category as $cat) $i++; for ($j = 0; $j < $i; $j++) { blah blah do da stuff... __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

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Programming Forums > Web Development and Design > PHP

SimpleXML issues