在PHP中从MySQL表创建多维数组树

Question

I'm trying to organize my mysql table into a multidimension php tree array.

For example, I'm trying to organize my products in a hierarchy for easy selection to narrow down the result the narrower they go in the result.

I am returned mysql rows like this:

Array
(
    [1] => Amazon
    [2] => Kindle Fire
    [3] => 
    [4] => 
    [5] => 
    [6] => 
    [7] => 
    [8] => 
    [9] => 1
)
Array
(
    [1] => Amazon
    [2] => Kindle Fire HD
    [3] => WiFi
    [4] => 7"
    [5] => 
    [6] => 16GB
    [7] => 
    [8] => 
    [9] => 2
)
Array
(
    [1] => Amazon
    [2] => Kindle Fire HD
    [3] => WiFi
    [4] => 7"
    [5] => 
    [6] => 32GB
    [7] => 
    [8] => 
    [9] => 3
)
Array
(
    [1] => Amazon
    [2] => Kindle Fire HD
    [3] => WiFi
    [4] => 8.9"
    [5] => 
    [6] => 16GB
    [7] => 
    [8] => 
    [9] => 4
)
Array
(
    [1] => Amazon
    [2] => Kindle Fire HD
    [3] => WiFi
    [4] => 8.9"
    [5] => 
    [6] => 32GB
    [7] => 
    [8] => 
    [9] => 5
)
Array
(
    [1] => Amazon
    [2] => Kindle Fire HD
    [3] => 4G LTE
    [4] => 8.9"
    [5] => 
    [6] => 32GB
    [7] => 
    [8] => 
    [9] => 6
)
Array
(
    [1] => Amazon
    [2] => Kindle Fire HD
    [3] => 4G LTE
    [4] => 8.9"
    [5] => 
    [6] => 64GB
    [7] => 
    [8] => 
    [9] => 7
)
Array
(
    [1] => Amazon
    [2] => Kindle Fire HDX
    [3] => Wifi
    [4] => 7"
    [5] => 
    [6] => 16GB
    [7] => 
    [8] => 
    [9] => 8
)
Array
(
    [1] => Amazon
    [2] => Kindle Fire HDX
    [3] => Wifi
    [4] => 7"
    [5] => 
    [6] => 32GB
    [7] => 
    [8] => 
    [9] => 9
)
Array
(
    [1] => Amazon
    [2] => Kindle Fire HDX
    [3] => Wifi
    [4] => 7"
    [5] => 
    [6] => 64GB
    [7] => 
    [8] => 
    [9] => 10
)

...etc

Note the last array value is the Product ID.

And I'm looking for help writing a recursive function that will result in an array that looks like:

Array(
    'Amazon' => Array(
         'Kindle Fire' => 1,
         'Kindle Fire HD' => Array(
              'WiFi' => Array(
                  '7"' => Array(
                      '16GB' => 2,
                      '32GB' => 3
                  )
                  '8.9"' => Array(
                      '16GB' => 4,
                      '32GB' => 5
                  )
              )
         )

    )
)

I've tried something like:

while($row = mysqli_fetch_row($res)) {
    $id = $row[0];
    unset($row[0]);
    unset($row[count($row)]);
        $row[] = $id; // Moves id to last array value

    for($i = 1; $i < count($row); $i++) {
        if($i == 1) {
            if(!array_key_exists($row[$i], $data)) {
                // Insert key
                $data[$row[$i]] = array();
            }
        }
        else {
            $level = $data[$row[$i-1]];

            if(array_key_exists($row[$i], $level)) {
                // Key exists
            }
            else {
                // Insert key

            }
        }
    }
}

Answer 1

I think your code has a good intention: using $level to hold the current depth. But at the moment this won't work, because you are copying via $level = $data[$row[$i-1]]; - instead you need to refer to it , eg with $level =& $data[$row[$i-1]]; .

$result = array();
while ($row = mysqli_fetch_row($res)) [
    $id = array_shift($row);

    if (!isset($maxIterator))
        $maxIterator = count($row)-1;

    $current =& $result;
    for ($i=0; $i<$maxIterator; $i++) {
        if (empty($row[$i]))
            break;
        if (!array_key_exists($row[$i], $current))
            $current[ $row[$i] ] = array();
        $current =& $current[ $row[$i] ];
    }
    //for properly ended and wasn't broken out of sooner
    if ($i == $maxIterator) {
        if (!array_key_exists($row[$i], $current))
            $current[ $row[$i] ] = 1;
        else
            $current[ $row[$i] ]++;
    }
}

array_shift basically does, what you needed two lines for: get the first element of an array and then remove it. Then I save the result of the count in a variable, so it doesn't need to be recalculated in every iteration of the for AND while .

Also I would suggest setting $maxIterator manually. With the shown result a good default would be 5 . This way all values before the 5th. will be used for nesting and the 5th itself will be used to count (in your example this is storage size).

As the for will execute $i++ after the last iteration (and then it fails the condition and hence the loop breaks), it can be used for the counting.

---

Personally I would overthink what exactly you are doing and maybe use a specifc structure for that. However, this code should give you a good impression how it can be solved using references.