PHP - Print nested array as unordered list

Question

I have the following heirachical array:

   Array
(
    [0] => stdClass Object
        (
            [name] => MD
            [children] => Array
                (
                    [0] => stdClass Object
                        (
                            [name] => Year 1
                            [children] => Array
                                (
                                    [0] => stdClass Object
                                        (
                                            [name] => Integrated Medical Sciences 1...

I want to print the names in the array as per the heirachical relationships as an unordered list. I have tried:

function walk($array){  
    foreach ($array as $key => $value) {
        echo "<ul>";
        if(!is_array($value->name)){
            echo "<li>$key:[$value->name]</li>";

            walk($value);
        }
        echo "</ul>";
    }
}

walk($roots);

But get the following, which contains the correct names and relationships, but also errors:

0:[MD]

    Notice: Trying to get property of non-object in /var/www/html/md/json/generate_json_by_year_print.php on line 65 Notice: Trying to get property of non-object in /var/www/html/md/json/generate_json_by_year_print.php on line 66
    name:[]
    Warning: Invalid argument supplied for foreach() in /var/www/html/md/json/generate_json_by_year_print.php on line 63 

    Notice: Trying to get property of non-object in /var/www/html/md/json/generate_json_by_year_print.php on line 65 Notice: Trying to get property of non-object in /var/www/html/md/json/generate_json_by_year_print.php on line 66
    children:[]
        0:[Year 1]
            Notice: Trying to get property of non-object in /var/www/html/md/json/generate_json_by_year_print.php on line 65 Notice: Trying to get property of non-object in /var/www/html/md/json/generate_json_by_year_print.php on line 66
            name:[]
            Warning: Invalid argument supplied for foreach() in /var/www/html/md/json/generate_json_by_year_print.php on line 63 
            Notice: Trying to get property of non-object in /var/www/html/md/json/generate_json_by_year_print.php on line 65 Notice: Trying to get property of non-object in /var/www/html/md/json/generate_json_by_year_print.php on line 66
            children:[]
                0:[Integrated Medical Sciences 1]
                    Notice: Trying to get property of non-object in /var/www/html/md/json/generate_json_by_year_print.php on line 65 Notice: Trying to get property of non-object in /var/www/html/md/json/generate_json_by_year_print.php on line 66
                    name:[]

Line 63 is foreach ($array as $key => $value) {

Line 65 is if(!is_array($value->name)){

Line 66 is echo "<li>$key:[$value->name]</li>";

UPDATE

OK tried:

function walk($array){  
    foreach ($array as $key => $value) {
        echo "<ul>";
        if(!is_array($value->name)){
            echo "<li>$key:[$value->name]</li>";
if (isset($value->children)) {
            walk($value->children);
}
        }
        echo "</ul>";
    }
}

walk($roots);

Which produces:

0:[MD]

    0:[Year 1]
        0:[Integrated Medical Sciences 1]
        1:[Integrated Medical Sciences 2]

    1:[Year 2]
        0:[Integrated Medical Practice 1]
            0:[Centralised Teaching]
                0:[Seminar - General Medicine Student Led Presentations]
                1:[Surgery - CBL]
            1:[Clinical Preparation]
                0:[Clinical Skills - Respiratory History Taking]
                1:[Seminar - Airways Disease]
                2:[Seminar - Approach to Head Injury and Altered Mental State]
                3:[Seminar - Atherothrombosis]
                4:[Seminar - Breast Cancer]
                5:[Seminar - Collapse]
                6:[Seminar - Cough]
                7:[Seminar - CVS Examination]
                8:[Seminar - Fatigue]
                9:[Seminar - GIT Examination]
                10:[Seminar - MSK Examination]
                11:[Seminar - Overview of CVS Disease]
                12:[Seminar - Overview of Gastroenterology ]
                13:[Seminar - Overview of Kidney and Urological Disease]
                14:[Seminar - Overview of Neurological Disease ]
                15:[Seminar - PVD]
                16:[Seminar - Spinal pain]
                17:[Seminar - Stroke]
                18:[TBL - Cardiac Conduction]
                19:[TBL - CRC]
                20:[TBL - Day 2 post ACS]
                21:[TBL - Infectious Gastro ]
                22:[TBL - Liver Disease]
                23:[TBL - Polyarthritis]
                24:[TBL - Sepsis]
                25:[TBL - Trauma and Fracture]
                26:[TBL - VTE]
                27:[Tutorial - Clinical Skills - Gastrointestinal History Taking]
                28:[Tutorial - CVS Chest Pain and Associated Symptoms]
            2:[Geriatric Medicine]
            3:[Internal Medicine]
                0:[RPH - Bedside Tutorial - Gastro]
                1:[RPH - Bedside Tutorials CVS and Resp]

Which is great. But I only want the names as text, not numbers and square brackets...

UPDATE

This is what I ended up using:

function walk($array)
{    
    //convert object to key-value array
    if (is_object($array)) {
        $array = (array)$array;
    }

    echo "<ul>";
    foreach ($array as $key => $value) {
        if (is_int($value) || is_string($value)) {
            echo "<li>" . $value;
        } elseif (is_array($value) || is_object($value)) {
            walk($value);
        }
        echo "</li>";
    }
    echo "</ul>";
}

walk($roots);

Notice: Undefined property: stdClass::$children in /var/www/html/md/json/generate_json_by_year_print.php on line 68 Warning: Invalid argument supplied for foreach() in /var/www/html/md/json/generate_json_by_year_print.php on line 63 — user12013126
– user12013126, Commented Sep 9, 2019 at 4:15
changing foreach ($array as $key => $value->children) { makes the line 66 error go away, but still left with the other errors. — user12013126
– user12013126, Commented Sep 9, 2019 at 4:18
If the children property might not exist (instead to an empty array - you don't provide enough sample data to know) you will need if (isset($value->children)) walk($value->children); — Nick
– Nick, Commented Sep 9, 2019 at 4:19

Ali Khalili · Accepted Answer · 2019-09-09 04:28:03Z

1

Your walk function assumes that the input is an array (a key value array in fact: foreach ($array as $key => $value)) and the values in this array should be objects ($value->name).

You should probably change your function to something like this:

/**
* @param array|\stdClass $array
*/
function walk($array)
{    
    //convert object to key-value array
    if (is_object($array)) {
        $array = (array)$array;
    }

    echo "<ul>";
    foreach ($array as $key => $value) {
        echo "<li>";
        echo $key;
        if (is_int($value) || is_string($value)) {
            echo ":" . $value;
        } elseif (is_array($value) || is_object($value)) {
            walk($value);
        }
        echo "</li>";
    }
    echo "</ul>";
}

answered Sep 9, 2019 at 4:28

Ali Khalili

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3 Comments

user12013126 Over a year ago

Thanks, that works but I need to have only the names show, not numbers, 'name' and 'children'

Ali Khalili Over a year ago

By names, you mean you need to print only the keys not the values? (if yes, just comment the echo ":" . $value; line)

user12013126 Over a year ago

No, keep the name vales but not the keys

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