JQuery Select2 - 從 PHP/MySQL 結果格式化嵌套列表

Question

我有一個Select2列表，我想用數據的嵌套結構填充它：

Level 1
  Condition 1
  Condition 2
Level 2
  Condition 3
  Condition 4
etc

JSON 需要采用以下格式：

data: [{
        'text': 'Level 1',
        'children': [{
            'id': 1,
            'text': 'Condition 1'
        }, {
            'id': 2,
            'text': 'Condition 2'
        }, ],
        'text': 'Level 2',
        'children': [{
            'id': 3,
            'text': 'Condition 3'
        }, {
            'id': 4,
            'text': 'Condition 4'
        }, ]
    }]

JQuery Select2：

$.ajax( {
                url: "scripts/get_conditions.php",
                dataType: 'json'
            } ).then( function ( response ) {
                $( "#condition_tree" ).select2( {
                    placeholder: "Select a Condition...",
                    allowClear: true,
                    width: 'resolve',
                    containerCssClass: "show-hide",
                    data: response
                } );
            } );

目前使用以下 PHP 和 MySQL 我不確定如何更改以產生所需的結果：

$query = 'SELECT * FROM mcondition ORDER BY mcondition_name ASC';
$result = $connection->query( $query );

$presentations = array();

while ($row = mysqli_fetch_array($result)) {
$mconditions[] = array("id"=>$row['mcondition_pk'], "text"=>$row['mcondition_name']);
}
echo json_encode($mconditions);
?>

和 mcondition 表：

+---------+-----------+------------------------------+
| mcondition_pk | mcondition_name | mcondition_level |
+---------+-----------+------------------------------+
| 1             | Condition 1     | Level 1          |
+---------+-----------+------------------------------+
| 2             | Condition 2     | Level 1          |
+---------+-----------+------------------------------+
| 3             | Condition 3     | Level 2          |
+---------+-----------+------------------------------+
| 4             | Condition 4     | Level 2          |
+---------+-----------+------------------------------+

注意 PHP 版本為 5.3.3，目前沒有升級機會。

Answer 1

使用級別名稱作為二維數組的鍵來收集您的數據，將每一行的數據添加到相應鍵下的子項中。

// fake mysql row data
$data = [
  ['mcondition_pk' => 1, 'mcondition_name' => 'Condition 1', 'mcondition_level' => 'Level 1'],
  ['mcondition_pk' => 2, 'mcondition_name' => 'Condition 2', 'mcondition_level' => 'Level 1'],
  ['mcondition_pk' => 3, 'mcondition_name' => 'Condition 3', 'mcondition_level' => 'Level 2'],
  ['mcondition_pk' => 4, 'mcondition_name' => 'Condition 4', 'mcondition_level' => 'Level 2'],
];

$temp = [];

// foreach loop over fake data, replace that with your original `while(…)` again
foreach($data as $row) {
  $temp[$row['mcondition_level']]['text'] = $row['mcondition_level'];
  $temp[$row['mcondition_level']]['children'][] = [
    'id' => $row['mcondition_pk'],
    'text' => $row['mcondition_name']
  ];
}

// replace the associative keys with simple numeric ones again
$temp = array_values($temp);

echo json_encode($temp);