RecursiveIterator不返回任何对象

Question

我有一个不返回特定数组结构中的对象/元素的递归函数：

尝试使用递归的数组im如下：

$feedStruct = [database] => Array
    (
        [property] => Array
            (
                [0] => Array
                    (
                        [title] => Array
                            (
                            )

                        [tipology] => Array
                            (
                            )

                        [description] => Array
                            (
                            )

                        [location] => Array
                            (
                            )

                        [year] => Array
                            (
                            )

                        [price] => Array
                            (
                            )

                        [area_plot] => Array
                            (
                            )

                        [habitable_area] => Array
                            (
                            )

                        [ref] => Array
                            (
                            )

                        [video] => Array
                            (
                            )

                        [default_photo] => Array
                            (
                            )

                        [photo1] => Array
                            (
                            )

                    )

                [1] => Array
                    (
                        [title] => Array
                            (
                            )

                        [tipology] => Array
                            (
                            )

                        [description] => Array
                            (
                            )

                        [location] => Array
                            (
                            )

                        [year] => Array
                            (
                            )

                        [price] => Array
                            (
                            )

                        [area_plot] => Array
                            (
                            )

                        [habitable_area] => Array
                            (
                            )

                        [ref] => Array
                            (
                            )

                        [video] => Array
                            (
                            )

                        [default_photo] => Array
                            (
                            )

                        [photo1] => Array
                            (
                            )

                    )

            )

    )

代码如下：

     $iterator = new RecursiveIteratorIterator(new RecursiveArrayIterator($feedStruct));
     $keys = array();
     foreach ($iterator as $key => $value) {
         // Build long key name based on parent keys
         for ($i = $iterator->getDepth() - 1; $i >= 0; $i--) {

          $val = $iterator->getSubIterator($i)->key();

          }
     }

当运行上面的数组时，它不会迭代，对于其他数组，我没有问题，你知道为什么吗？

谢谢

Answer 1

您的$iterator = new RecursiveIteratorIterator(new RecursiveArrayIterator($feedStruct));将被解释为$iterator = new RecursiveIteratorIterator(new RecursiveArrayIterator($feedStruct), RecursiveIteratorIterator::SELF_FIRST);，因为RecursiveIteratorIterator::LEAVES_ONLY是三个参数中的默认参数(即RecursiveIteratorIterator::SELF_FIRST、RecursiveIteratorIterator::CHILD_FIRST)。

我将尝试解释参数。假设您有下面的数组

$array = array(
    0 => array(
        'city' => 'Jos',
        'places_to_visit' => array(
            'Lagos',
            'Capetown'
        )
    ),
    1 => "sd"
);
$iterator = new RecursiveIteratorIterator(new RecursiveArrayIterator($feedStruct), $mode);
$keys = array();
foreach ($iterator as $key => $value) {
// Build long key name based on parent keys
    for ($i = $iterator->getDepth() - 1; $i >= 0; $i--) {
        $val[] = $iterator->getSubIterator($i)->key();
    }
}

RecursiveIteratorIterator::LEAVES_ONLY表示只迭代每个结构中的最后一个值。在上述数组$array的情况下，如果为$mode = RecursiveIteratorIterator::LEAVES_ONLY，

print_r($val); 
/* Outputs
city => Jos
0 => Lagos
1 => Capetown
1 => sd */

RecursiveIteratorIterator::CHILD_FIRST表示先迭代子值，然后再迭代父值。在上述数组$array的情况下，如果为$mode = RecursiveIteratorIterator::CHILD_FIRST，

print_r($val); 
/* Outputs
city => Jos
0 => Lagos
1 => Capetown
places_to_visit => Array()
0 => Array()
1 => sd */

RecursiveIteratorIterator::SELF_FIRST意味着只迭代每个结构中的父值。在上述数组$array的情况下，如果为$mode = RecursiveIteratorIterator::SELF_FIRST，

print_r($val); 
/*Outputs 
0 => Array()
city => Jos
places_to_visit => Array()
0 => Lagos
1 => Capetown
1 => sd */

在您的示例中，$iterator将返回，因为在您的结构$feedStruct中没有叶子(最终值)。试试RecursiveIteratorIterator::SELF_FIRST，效果很好。