Display categories and subcategories in php mysql

Question

Cant get categories and subcategories in php mysql.

Here i get all categories (cats and subcats):

function get_categories() {
    $conn = db_connect();
    $query = "select * from categories";
    $result = $conn->query($query);
    if(!$result) {
        return false;
    }else {
        $result = db_result_to_array($result);
        return $result;
    }
}

And here i get subcats:

function get_child_cats($parent_id) {
    $conn = db_connect();

    $query = "select * from categories where parent_id = '".$parent_id."'";

    $result = $conn->query($query);

    if(!$result) {
        return false;
    }else {
        $result = db_result_to_array($result);
        return $result;
    }

}

The db_result_to_array() function is here:

    function db_result_to_array($result) {
    $res_array = array();
    for($count = 0; $row = $result->fetch_assoc(); $count++) {
        $res_array[$count] = $row;
    }
    return $res_array;
}

DB consists of cat_id, cat_name, parent_id

Here i am trying to display cats and subcats:

    if(is_array($categories)) {
    echo "<ul>";
    foreach($categories as $row) {

        if(!$row['parent_id']) {
            $childs = get_child_cats($parent_id);
            echo "<li>".$row['cat_name'];
            if($row['parent_id']) {
                echo "<ul>";
                foreach($childs as $row) {
                    echo "<li>".$row['cat_name']."</li>";
                }
                echo "</ul>";
            }
            echo "</li>";
        }

    }
    echo "</ul>";
}

However, i am getting only cats without any subcats.

Answer 1

You have written wrong logic, think your first condition is if(!$row['parent_id']) { and afterwards inside it you add condition if($row['parent_id']) { . so if "false" condition satisfy and cursor goes inside "if" then how it would be possible to execute logic for "true" for the same parameter and condition

I have tried below to make your logic correct:

foreach($categories as $row) {
    if(!$row['parent_id']) {
        echo "<li>".$row['cat_name'];
        $childs = get_child_cats($parent_id);

    }
    else {
        echo "<ul>";
        foreach($childs as $row) {
            echo "<li>".$row['cat_name']."</li>";
         }
       echo "</ul>";
    }
    echo "</li>";
}

Hope it works for you!