How to reorder this array?

Question

I have a database table as follows:

This returns all column titles in the pic, but the one's that are most important are slug, and parent (not sure about id_button).

The array gets ordered automatically by id_button ASC, which really irks me. But, anyways, this is not important, as I need to order it completely different, or re-order it after the array is populated.

The array returns this, by order of id_button:

$new_menu_buttons = array(
    0 => array(
            'id_button' => 1,
            'parent' => 'help',
            'position' => 'child_of',
            'slug' => 'testing',
    ),
    1 => array(
            'id_button' => 2,
            'parent' => 'packages',
            'position' => 'after',
            'slug' => 'sub_test_1',
    ),
    2 => array(
            'id_button' => 3,
            'parent' => 'google.com',
            'position' => 'after',
            'slug' => 'another_test',
    ),
    3 => array(
            'id_button' => 4,
            'parent' => 'testing'
            'position' => 'child_of',
            'slug' => 'google.com',
    )
);

I need to order it so that if a slug is found within any parent, than the slug that is in the parent needs to be loaded before the one that has it defined within the parent.

Its not important if it is directly before it. For example, you see testing is the first slug that gets returned, and yet the parent for this is the last slug (google.com). So as long as the slug row where the parent is defined gets ordered so that it is BEFORE the row that has the slug value in the parent column, everything is fine.

So in this situation, it can be reordered as any of these 3 ordered arrays below:

$new_menu_buttons = array(
    0 => array(
            'id_button' => 1,
            'parent' => 'help',
            'position' => 'child_of',
            'slug' => 'testing',
    ),
    1 => array(
            'id_button' => 2,
            'parent' => 'packages',
            'position' => 'after',
            'slug' => 'sub_test_1',
    ),
    2 => array(
            'id_button' => 4,
            'parent' => 'testing',
            'position' => 'child_of',
            'slug' => 'google.com',
    ),
    3 => array(
            'id_button' => 3,
            'parent' => 'google.com'
            'position' => 'after',
            'slug' => 'another_test',
    )
);

OR this...

$new_menu_buttons = array(
    0 => array(
            'id_button' => 1,
            'parent' => 'help',
            'position' => 'child_of',
            'slug' => 'testing',
    ),
    1 => array(
            'id_button' => 4,
            'parent' => 'testing',
            'position' => 'child_of',
            'slug' => 'google.com',
    ),
    2 => array(
            'id_button' => 2,
            'parent' => 'packages',
            'position' => 'after',
            'slug' => 'sub_test_1',
    ),
    3 => array(
            'id_button' => 3,
            'parent' => 'google.com'
            'position' => 'after',
            'slug' => 'another_test',
    )
);

OR even this...

$new_menu_buttons = array(
    0 => array(
            'id_button' => 1,
            'parent' => 'help',
            'position' => 'child_of',
            'slug' => 'testing',
    ),
    1 => array(
            'id_button' => 4,
            'parent' => 'testing',
            'position' => 'child_of',
            'slug' => 'google.com',
    ),
    2 => array(
            'id_button' => 3,
            'parent' => 'google.com'
            'position' => 'after',
            'slug' => 'another_test',
    ),
    3 => array(
            'id_button' => 2,
            'parent' => 'packages',
            'position' => 'after',
            'slug' => 'sub_test_1',
    )
);

All 3 of these ordered arrays will work because the array with the slug that matches the parent is before the array with the matching parent, and since the slug value, sub_test_1 doesn't match any of the parent values this array order is unimportant, so that array can be located anywhere within the array.

How can I do this? I'm thinking of just looping through the array somehow and trying to determine if the slug is in any of the parents, and just do a reordering somehow...

In short, the slug needs to be ordered before the parent ONLY if there is a parent that matches a slug within the array. Otherwise, if no match is found, the order isn't important.

Answer 1

As Niko suggested, databases support powerful sorting functionality, so you normally can best solve this by telling the database in which order to return the data. If the data is queried with SQL, that's the ORDER BY clause. This is specified in the documentation of your database, assuming you're using MySQL 5.0: http://dev.mysql.com/doc/refman/5.0/en/sorting-rows.html

If you can not influence the order on the database level, you're in the need to sort the array in PHP. You actually have an array of arrays, in which the outer array is just a list having the id (primary key) of each row and the other fields as a fieldname -> value array as a value (inner array).

Your sort is *user-defined` - you specify the sort order. A common way is to have a sort function that compares two entries which each other. That sort function needs to decide which of those two is of a higher sort-order than the other (or both have the same weight). In you case one item is higher than the other if one is the child of the other.

That's the general principle. You define the sort function that decides (the so called callback function), and PHP takes care to feed it with the array data to sort with the usort^Docs function.

A sub-problem you need to solve then is to decide whether or not a child exists in the whole array (an item with a slug having the same value as parent). As this all looks like it can be a bit more complex, it's wise to encapsulate this all into a class of it's own.

Example / Demo:

class menuButtons
{
    /**
     * @var array
     */
    private $buttons;

    public function __construct(array $buttons)
    {
        $this->buttons = $buttons;
    }


    public function sortChildsFirst()
    {
        $buttons = $this->buttons;
        usort($buttons, array($this, 'sortCallback'));
        return $buttons;
    }

    private function sortCallback($a, $b)
    {
        // an element is more than any other if it's parent
        // value is any other slugs value

        if ($this->slugExists($a['parent']))
            return 1;

        return -1;
    }

    private function slugExists($slug)
    {
        foreach($this->buttons as $button)
        {
            if ($button['slug'] === $slug)
                return true;
        }
        return false;
    }
}

$buttons = new menuButtons($new_menu_buttons);

$order = $buttons->sortChildsFirst();

Note: This code is exploiting the fact that your sort order is only roughly specified. You only wrote that you need to have children before parents, so if you take all children first, this will always be the case. It's not that each parent will directly follow the child.

Nevertheless, this skeleton class can work as a base to further improve the search functionality as it's fully encapsulated. You can even change the whole sort method, e.g. to completely write one of your own even w/o usort, like outlined below. The main code does not need to change as it's only making use of the sortChildsFirst method.

Answer 2

You can sort an array once populated using the usort() function.

http://php.net/manual/en/function.usort.php