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xml child/parent help
Hi,

I have been trying to build a child/parent navigation for a little while now using PHP (I'm from a .net background) and I can't get close to the desired results. I am loading my data from an xml file using simplexml successfully but I am trying to workout how I can map that into arrays or variables so I can write it out.

The xml is
  <Categories>
  <Category>
    <ID>1</ID>
    <Title>Days</Title>
    <Description />
    <ParentID />
    <Meta />
  </Category>
  <Category>
    <ID>2</ID>
    <Title>Monday</Title>
    <Description />
    <ParentID>1</ParentID>
    <Meta />
  </Category>
  <Category>
    <ID>3</ID>
    <Title>Tuesday</Title>
    <Description />
    <ParentID>1</ParentID>
    <Meta />
  </Category>
  <Category>
    <ID>4</ID>
    <Title>Wednesday</Title>
    <Description />
    <ParentID>1</ParentID>
    <Meta />
  </Category>
  <Category>
    <ID>5</ID>
    <Title>Thursday</Title>
    <Description />
    <ParentID>1</ParentID>
    <Meta />
  </Category>
  <Category>
    <ID>6</ID>
    <Title>Friday</Title>
    <Description />
    <ParentID>1</ParentID>
    <Meta />
  </Category>
  <Category>
    <ID>7</ID>
    <Title>Saturday</Title>
    <Description />
    <ParentID/>
    <Meta />
  </Category>
  <Category>
    <ID>8</ID>
    <Title>Sunday</Title>
    <Description />
    <ParentID/>
    <Meta />
  </Category>
</Categories>
Now my PHP 
foreach($categories as $category) {

				if ($category->ParentID != "")
				{
					echo "<li><a href=index.php?Cat=$category->ID>$category->Title</a></li>";
					echo "<ul>";
					foreach($categories as $subcategory) {
					if ($subcategory->ParentID == $category->ID)
					{
						echo "<li><a href=index.php?Cat=$subcategory->ID>$subcategory->Title</a></li>";
					}
					}
					echo "</ul>";
				}
				else
				{
					echo "<li><a href=index.php?Cat=$category->ID>$category->Title</a></li>";
				} 
			} 
			echo "</ul>";
So my desired output would be something like this: 
<ul id="p7menubar">
<li><a class="trigger" href="#">Days</a>
<ul>
<li><a href="#">Monday</a></li>
<li><a href="#">Tuesday</a></li>
<li><a href="#">Wednesday</a></li>
<li><a href="#">Thursday</a></li>
<li><a href="#">Friday</a></li>
</ul>
</li>
<li><a href="index.htm">Saturday</a></li>
<li><a href="index.htm">Sunday</a></li>
</ul>



If anyone could help me out it would be very much appreciated :)

Thanks

Al
Started: September 19, 2011 Latest Activity: June 11, 2018 php xml
2 Answers
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Posted: Ellgaibra
In: June 11, 2018

If your data is going to be tree-structured (which it seems to be — each parent has multiple children), why not store them in an XML like this?
<?xml version="1.0"?>
<Categories>
  <Category>
    <Title>Days</Title>
    <Description/>
    <Meta/>
    <Categories>
      <Category>
        <Title>Monday</Title>
        <Description/>
        <Meta/>
      </Category>
      <Category>
        <Title>Tuesday</Title>
        <Description/>
        <Meta/>
      </Category>
      <Category>
        <Title>Wednesday</Title>
        <Description/>
        <Meta/>
      </Category>
      <Category>
        <Title>Thursday</Title>
        <Description/>
        <Meta/>
      </Category>
      <Category>
        <Title>Friday</Title>
        <Description/>
        <Meta/>
      </Category>
    </Categories>
  </Category>
  <Category>
    <Title>Saturday</Title>
    <Description/>
    <Meta/>
  </Category>
  <Category>
    <Title>Sunday</Title>
    <Description/>
    <Meta/>
  </Category>
</Categories>
You need two instances of the list otherwise you are changing the index mid iteration. My advice is the top area:
if (file_exists('cats.xml')) {
    $xml = simplexml_load_file('cats.xml');
    $categories = simplexml_load_file('cats.xml');
} else {
    exit('Failed to open cats.xml.');
}
echo "<ul>";
foreach($categories as $category) {
    if (!(int)$category->ParentID > 0){
        // if the parentid is not set this is a root element and we want to print it and
        // it's children.
        categorylist($category, $xml);
    }
} 
echo "</ul>";
function categorylist($current, $list){
    // so echo the item list and link opener, but not the closer
    echo "<li><a href='index.php?Cat=$current->ID'>$current->Title</a>";
    // we need to count the number of children
    $count = 0;
    foreach($list as $item){
            // just iterate through the list for a match
        if ((int)$item->ParentID == (int)$current->ID){
            if($count == 0){
                            // if its the first match open the new child list tag
                echo "<ul>";
            }
                    // print the child link and item and iterate the counter
            echo "<li><a href=index.php?Cat=$item->ID>$item->Title</a></li>";
            $count = $count + 1;
        }
    }
    if($count > 0){
            // if their were children print the close of the list
        echo "</ul>";
    }
    // now close the list item.
    echo "</li>";
}
this gets the output you describe but no more, though it hints at the method you would use to create a recursive version. Of course cats.xml contains your xml content above.

Posted: MacOS
In: September 19, 2011

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