How to iterate a nested array?

Question

I need to print the below array structure as:

Node Title 1

  topic 1

  topic 2

  topic 3

  topic 4

    asset title1 

    asset title2

    asset title3

How can i do using foreach - PHP

What i have done is :

foreach($output['fields'] as $key => $value) {
        if($key == 'title') {
            echo $value;
        }
        if(count($value['main_topic'])) {
            foreach($value['main_topic'] AS $mainkey => $main_topic) {
                echo $main_topic['topic_title'];
            }
        }
    }

The above syntax is printing the title. But not the main_topic array.

Sayed Mohd Ali · Accepted Answer · 2018-12-05 13:43:42Z

That is because you are iterating over all $output['fields']. There will never be a $value with key 'main_topic' because the key 'main_topic' is contained in the $output['fields'] array and thus exists only as $key in your foreach. The array you want is $value

Your code should be like:

foreach($output['fields'] as $key => $value) {
        if($key == 'title') {
            echo $value;
            continue;
        }
        if($key == 'main_topic' && is_array($value)) {
            foreach($value as $main_topic) {
                echo $main_topic['topic_title'];
            }
        }
    }

To complete this answer with a full solution (including asset titles), below is how I would write it.

Because $output['fields'] is the starting point and to make the code more readable, I create a reference to the starting node using the =& operator so the array is not copied in memory. I do the same with the inner foreachs. Since we are not modifying data, referencing the variables is sufficient and consumes less memory and CPU:

if (is_array($output['fields'])) {
    $node =& $output['fields'];
    echo $node['title'];
    if(is_array($node['main_topic'])) {
        foreach($node['main_topic'] as &$main) {
            echo $main['topic_title'];
            if(is_array($main['subfield'])) {
                foreach($main['subfield'] as &$asset) {
                    echo $asset['asset_title'];
                }
            }
        }
    } 
}
else {
    echo "no menu";
}

yes i just realized myself that i stopped fixing the code right after the first mistake. i corrected the inner-foreach too in my edit.
Post has been edited to give a more elaborative explanation on $node =& $output['node'];

fire · Accepted Answer · 2012-02-08 11:11:54Z

1

$value is the array, not $key['main_topic']

foreach($output['fields'] as $key => $value) {
    if($key == 'title') {
        echo $value;
    }
    if($key == 'main_topic') {
        foreach($value as $mainkey => $main_topic) {
            echo $main_topic['topic_title'];
        }
    }
}

answered Feb 8, 2012 at 11:11

fire

21.5k18 gold badges82 silver badges116 bronze badges

Comments

djot · Accepted Answer · 2012-02-08 11:10:44Z

0

Try this, you need the additional key:

echo $value['main_topic'][$mainkey]['topic_title'];

answered Feb 8, 2012 at 11:10

djot

2,9474 gold badges21 silver badges28 bronze badges

1 Comment

Simon Germain Over a year ago

$main_topic is the iterated object. No need to specify a key.

DaveyBoy · Accepted Answer · 2012-02-08 11:23:16Z

You're getting your array sections confused.

Try (and I haven't tested this) :

echo $output['node_title']."\n";
foreach ($output['fields'] as $key=>$value)
{
    switch ($key)
    {
        case 'title':
            echo $value."\n";
            break;
        case 'main_topic':
            if (count($value) > 0)
            {
                foreach ($value as $main_block)
                {
                    echo "\t".$main_block['topic_title']."\n";
                    if (array_key_exists('subfield',$main_block)!==FALSE)
                    {
                        foreach ($main_block['subfield'] as $subfield_block)
                        {
                            echo "\t\t".$subfield_block['asset_title']."\n";
                        }
                    }
                }
            }
            break;
        default:
            break;
    }
}

Collectives™ on Stack Overflow

How to iterate a nested array?

4 Answers 4

2 Comments

Comments

1 Comment

Comments

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

2 Comments

Comments

1 Comment

Comments

Related