How to get categories in wordpress - php

Question

I want to get all categories in wordpress site but separately parent and child categories(in such way it's easily for me to style). In the following code I get parent categories but all children categories are repeated for every parent.
Thanks!
<?php
$args = array(
'orderby' => 'name',
'parent' => 0
);
$categories = get_categories( $args );
$categories_sub = get_categories();
foreach ( $categories as $category ) {
echo '<ul class=" span-5 colborder list_main "> ' . $category->name . '<br/>';
foreach ( $cat->parent > 1 and $categories_sub as $cat) {
$temp=$category->name + '/';
if(get_category_parents($cat)==$temp) {
echo '' . $cat->name . '<br/>';
}
$temp="";
}
echo '</ul>';
}
?>

Answer 1

There are several ways to create HTML list of categories.
wp_list_categories()
Default CSS selectors
Simplest way is to display a list of categories with wp_list_categories() and style the output with default CSS selectors:
li.categories
li.cat-item
li.cat-item-7
li.current-cat
li.current-cat-parent
ul.children
The Walker_Category class
The Walker class is for traversing the hierarchical data like menus or categories. It is an abstract class that has four abstract methods start_el(), end_el(), start_lvl(), end_lvl(). It is not required to override all abstract methods of the class, only those methods that are needed.
$args = array( 'hide_empty' => false, 'walker' => new MyWalker(), 'title_li' => false );
wp_list_categories( $args );
class MyWalker extends Walker_Category {
function start_el( &$output, $category, $depth = 0, $args = array(), $id = 0 ) {
$output .= '<a href="' . get_category_link( $category->term_id ) . '" >' . $category->name . '</a><br/>';
}
function end_el( &$output, $page, $depth = 0, $args = array() ) {}
function start_lvl( &$output, $depth = 0, $args = array() ) {
$output .= '<ul class="span-5 colborder list_main">'.PHP_EOL;
}
function end_lvl( &$output, $depth = 0, $args = array() ) {
$output .= '</ul>'.PHP_EOL;
}
}
Recursive Function
Recursive Function is also a good way to traverse through categories. This way you have to manually get the categories on each node. Since the get_categories() function returns all the children categories in all subnodes, id of the current category must be passed on to be able to display only the current level categories.
get_the_categories();
function get_the_categories( $parent = 0 )
{
$categories = get_categories( "hide_empty=0&parent=$parent" );
if ( $categories ) {
echo '<ul class="span-5 colborder list_main">';
foreach ( $categories as $cat ) {
if ( $cat->category_parent == $parent ) {
echo '<a href="' . get_category_link( $cat->term_id ) . '" >' . $cat->name . '</a><br/>';
get_the_categories( $cat->term_id );
}
}
echo '</ul>';
}
}

Answer 2

i had implemented this code a while ago but you can give it a try..
// get_categories() function will return all the categories
$upaae_categories = get_categories( array(
'orderby' => 'name',
'order' => 'ASC'
) );
foreach( $upaae_categories as $single_cat ) {
if($single_cat->parent < 1) // Display if parent category and exclude child categories
{
echo 'Parent: '.$single_cat->name;
// now get all the child categories
$child_categories=get_categories(
array( 'parent' => $single_cat->term_id )
);
if(sizeof($child_categories)>0){ /* this is just for ensuring that this parent category do have child categories otherwise a category cannot be a parent if does not have any child categories*/
echo '###childs###</br>'
foreach ($child_categories as $child) {
echo $child->name.'</br>';
}// end of loop displaying child categories
} //end of if parent have child categories
}
}