How to convert this simple array into nested php array?

Question

Hi I have this simple php array containing category hierarchy

<?php

$categories = [
    'Games',
    '-Sports',
    '--Footbal',
    '--Basketball',
    '-Action',
    '--FPS',
    '--RPG',
    '-SIM',
];

Once echo, it will looks like this (A simple category hierarychy):

Games
-Sports
--Footbal
--Basketball
-Action
--FPS
--RPG
-SIM

Currently I want to use the Bootstrap Tree plugin by https://github.com/jonmiles/bootstrap-treeview and need to prepare my data to look like this

var tree = [
  {
    text: "Games",
    nodes: [
      {
        text: "Sports",
        nodes: [
          {
            text: "Footbal"
          },
          {
            text: "Basketball"
          }
        ]
      },
      {
        text: "Action",
        nodes: [
          {
            text: "FPS"
          },
          {
            text: "RPG"
          }
        ]
      },
      {
        text: "SIM"
      }
    ]
  }
];

I understand I need to build an array first and later convert it into JSON. Question is how do I convert my existing array into compatible array for the required JSON?

My code so far

<?php

$categories = [
    'Games',
    '-Sports',
    '--Footbal',
    '--Basketball',
    '-Action',
    '--FPS',
    '--RPG',
    '-SIM',
];

$tree_key = 0;

if (!empty($categories)) {
            foreach ($categories as $category) {

                $tree_label = $category;

                $count = substr_count($tree_label, '-');

                //if no dash (-) found, make it parent category
                if (empty($count)) {
                    $tree_key = $category;
                    $tree_array[$tree_key] = ['text'=>$category];
                }
                else
                {
                    //if one dash found, make it child of previous parent category
                    if ($count === 1) {
                        $tree_array[$tree_key]['nodes'][] = ['text'=>$category];
                    } else {

                    }
                }


            }
        }

Thanks guys for helping!

Do you just need this one json object, or do you want code that can do it no matter what the array is — Matthew Bergwall
– Matthew Bergwall, Commented Sep 20, 2017 at 14:42
As a Tree is a recursive data model I would suggest a recursive approach to this problem — gogaz
– gogaz, Commented Sep 20, 2017 at 14:42
@MatthewBergwall depending the number of the dash (-), I wan to keep it nested, but usually the data is pretty much like the example above, so if I can achieve that already good :) — Nedi Sidi
– Nedi Sidi, Commented Sep 20, 2017 at 14:48
@gogaz recursive approach, can I know what should I google it? — Nedi Sidi
– Nedi Sidi, Commented Sep 20, 2017 at 14:49

brevis · Accepted Answer · 2017-09-20 15:40:14Z

1

Try this:

function buildTree($data, $currentDepth = 0, $startIndex = 0) {
    $tree = array();
    foreach ($data as $i=>$c) {
        if ($i < $startIndex) {
            continue;
        }

        $depth = 0;
        if (preg_match('/^([-]*)/', $c, $m)) {
            $depth = strlen($m[1]);
        }

        if ($depth < $currentDepth) {
            break;
        } elseif ($depth != $currentDepth) {
            continue;
        }

        $node = array('text' => preg_replace('/^[-]*/', '', $c));
        $nodes = buildTree($data, $depth + 1, $i + 1);
        if (count($nodes) > 0) {    
            $node['nodes'] = $nodes;
        }

        $tree[] = $node;
    }
    return $tree;
}

$categories = [
    'Games',
    '-Sports',
    '--Footbal',
    '--Basketball',
    '-Action',
    '--FPS',
    '--RPG',
    '-SIM',
];

echo json_encode( buildTree($categories), JSON_PRETTY_PRINT );

Online demo

edited Sep 20, 2017 at 15:40

answered Sep 20, 2017 at 15:33

brevis

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1 Comment

Nedi Sidi Over a year ago

Thanks your answer works perfectly, looking at your code I wonder how I can reach the level to write this kind of code. Thanks again mr @brevis

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