[SOLVED] help with recursive function

[digitalgod]

hey guys,

 

I'm trying to build a recursive function to display all of my categories and subcategories but I keep running into some logic problems...

 

what I basically need it to do is echo something like this

<li><span class="folder">Folder 1</span></li>
  <li><span class="folder">Folder 2</span>
    <ul>
      <li><span class="folder">Subfolder 2.1</span>
        <ul id="folder21">
          <li><span class="folder">Subfolder 2.1.1</span></li>
        </ul>
      </li>
      <li><span class="folder">Subfolder 2.2</span></li>
    </ul>
  </li>

 

so main folder that don't have any children are between <li></li> tags, folders that do have children have <ul></ul> before the closing </li>

I can't figure this out and I know it shouldn't be that hard but it's getting late and I'm extremely tired...

 

this is what I have right now and it's no where near what I want it to do

 

function recursiveTree($parent, $level) {

   $result = mysql_query('SELECT * FROM image_category '.
			 'WHERE parent_id="'.$parent.'";');
   $result_count = mysql_num_rows($result);
   
   // display each child
   while ($row = mysql_fetch_array($result)) {
   $new_level = $level + 1;
  	   
   if ( $new_level == 1 )
   {
   	echo '<li><span class="folder">'.$row['title'].'<ul>';
   } else
   {
   	echo '<li><span class="folder">'.$row['title'];
	if ( $result_count == 1 || $result_count == $new_level )
	{
		echo '<ul>';
	} else
	{
		echo '</li></ul>';
	}
   }
   
   recursiveTree($row['image_category_id'], $level+1);
   }
} 

 

[ignace]

function recursiveTree($parent) {

  $result = mysql_query('SELECT * FROM image_category '.
			 'WHERE parent_id="'.$parent.'";');
  $result_count = mysql_num_rows($result);
  
  // display each child
  echo '<ul>';
  while ($row = mysql_fetch_array($result)) {
      if ($parent !== $row['image_category_id']) { // or something else that changes and means that we are going a level deeper
   recursiveTree($row['image_category_id']);
      } else {
          echo '<li><span class="folder">' . $row['title'] . '</span></li>';
      }
  }
  echo '</ul>';
}

 

post your table fields

[digitalgod]

hey ignace, that actually won't echo out anything because main folders have no parent_id so they're parent_id value is 0 if that makes any sense... That's why I had $level, to keep track of how deep it goes in one branch

 

that table image_category has

 

image_category_id | parent_id | title | description | created

 

 

 

[digitalgod]

anyone? I'm really going crazy trying to get this function to work

[akitchin]

it's a pretty simple matter, but it can be tricky to nail down.  the solution is to wrap a <ul> around the entire list if it is a child of something, since all children have parents:

 

<?php
function recursiveTree($parent = 0) {

   // if this is a child, add a set of <ul> tags
   if ($parent > 0)
   {
      echo '<ul>';
   }

   $result = mysql_query('SELECT * FROM image_category '.
			 'WHERE parent_id="'.$parent.'";');
   
   // display each child
   while ($row = mysql_fetch_array($result)) {
  	echo '<li><span class="folder">'.$row['title'].'</span>';
  	recursiveTree($row['category_id']);
  	echo '</li>';
   }

   // if this is a child, finish off the <ul> tag
   if ($parent > 0)
   {
      echo '</ul>';
   }
}
?>

 

give that a whirl.  to be honest, i'm not incredibly experienced with recursives so i can't promise that will solve your problem.  worth a shot though.

[digitalgod]

thanks akitchin! I've always hated recursives...

 

my only problem though is that it creates unnecessary markup ( I'm a neat freak as well as a web standards freak hehe) but I've lost so much time trying to get those damn <ul> tags to close at the right place that I don't really mind.

 

One question though, is there a way to keep the generated markup nice and clean, because right now it prints everything on one line and adding \n isn't helping...

[akitchin]

try adding chr(10) and chr(13) whenever you want a linebreak (and a tab character to move it across).  those two together are a newline and a return carriage.  some browsers need both to render the line break.

 

as for unnecessary markup, is that not what you wanted in terms of the <ul></ul> tags?  it (should) generate one set for each child, regardless of level.  is that not what it is spitting out?

[digitalgod]

thanks for the tip!

 

Here I'll show you what I mean by unnecessary markup:

 

<ul id="browser" class="filetree">
  <li><span class="folder">main</span>
    <ul>
      <li><span class="folder">sub-main</span>
        <ul> <!-- unnecessary -->
        </ul> <!-- unnecessary -->
      </li>
    </ul>
  </li>
  <li><span class="folder">main #2</span>
    <ul>
      <li><span class="folder">test #2</span>
        <ul>
          <li><span class="folder">test #4</span>
            <ul>
              <li><span class="folder">test #5</span>
                <ul> <!-- unnecessary -->
                </ul> <!-- unnecessary -->
              </li>
            </ul>
          </li>
        </ul>
      </li>
      <li><span class="folder">test #3</span>
        <ul> <!-- unnecessary -->
        </ul> <!-- unnecessary -->
      </li>
    </ul>
  </li>
</ul>

[akitchin]

my bad - move the if() statement to below the query (but before the while loop) and check mysql_num_rows() on the resource to verify that it's got more than 0.  if it fails on either parent > 0 or num_rows > 0, then it shouldn't display <ul> (nor </ul>).

[digitalgod]

it still doesn't work, I'll try to figure it out later on, I'll put it on my to do list.

 

thanks for your help akitchin!