print multilevel child parent categories into optgroup and selectbox

Question

i have this category MySql table:

id , name , parent

Now with this function i list categories in selectbox and optgroup html tags:

$options    = array();
$categories = DataAccess::fetch("
  SELECT 
    * , p.name AS parent 
  FROM 
    cats AS child
  INNER JOIN
    cats AS p ON p.id = child.parent
");
foreach($categories as $category){
  $parent = $category['parent'];
  if (! isset($options[$parent])) $options[$parent] = array();
  $options[$parent][$category['id']] = $category['name'];
}
echo '<select>';
$selid = 13;
foreach($options as $group => $option) {
  printf('<optgroup label="%s">', $group);
  foreach ($option as $id => $label) {
   $selcat = ($selid == $id) ? 'selected' : '';
    printf('<option %s value="%s">%s</option>',$selcat, $id, $label);

  }
  printf('</optgroup>');
}
echo "</select>";

This function ouhput worked for One child parent categories and output is:

<select class="selectpicker" >
   <optgroup label="News">
     <option selected value="13">War</option>
   </optgroup>
   <optgroup label="article">
     <option selected value="14">tech</option>
   </optgroup>
</select>

Now, I have Three problem:

1- if i create many child This function notwork and print only One Child. i need to Like This:

News
--Sport
--War
--tech
Article
--tech
--php
--linux

2 - in need to print Multilevel categories with optgroup Like This:

News
--Sport
----Sky
----Football
------Football-1
--War
----War1
--tech
Article
--tech
----tech2
------tech3
--php
--linux

3 - Not Print categories if parent = 0 (root), This print only categories with child parent.

how do fix/print this?

score 1 · Answer 1 · edited May 23 '17 at 12:31

You can't. select and optgroup don't support multiple levels although standard says they should. You'll have to manually left pad your options with   according to their level. Normal spaces don't work.

You don't seem to have implemented this multilevel tree yet. I'd start by reading the answers on this question.

Then I'd write a simple recursive function like this:

function walkTree($nodes, $level = 0) {
    foreach($nodes as $node) {
        echo '<option>' . str_repeat('&nbsp;', $level) . $node->label . '</option>';
        if($node->children) {
            walkTree($node->children, $level + 1); 
        }
    }
}

walkTree($root->children);

This assumes you have an object hierarchy, but it's not necessary. You can use your existing database and write a function that returns all child nodes of another node:

function getChildren($id) {
    $categories = DataAccess::fetch("
      SELECT 
        *
      FROM 
        cats
      WHERE 
        cats.parent = $id
    ");

    return $categories;
}

Then you'd need to get the initial list of root nodes (WHERE cats.parent IS NULL maybe?) and pass it to walkTree, where $node->children is replaced by getChildren($node->id).

Obviously this means a lot of querying. You either need to switch to a nested set hierarchy or something similar, or maybe cache the resulting HTML.

print multilevel child parent categories into optgroup and selectbox

1 Answers1