从php中的关联数组键中删除特定记录

Question

Hi I have an array that contains two arrays that has the following structure:

categories [
  "lvl0" => array:2 [
    0 => "Cleaning"
    1 => "Bread"
  ]
  "lvl1" => array:2 [
    0 => null
    1 => "Bread > rolls"
  ]
]

I would like to remove any records of NULL from the 'lvl1' array but have not been able to find the correct method to do this.

I have tried:

array_filter($categories['lvl1'])

But this also removes all records associated to lvl1 and not just the NULL ones.

Any help would be greatly appreciated.

Thanks

Answer 1

array_filter() takes a callback as the second argument. If you don't provide it, it returns only records that aren't equal to boolean false . You can provide a simple callback that removes empty values.

array_filter() also uses a copy of your array (rather than a reference), so you need to use the return value.

For instance:

$categories = [
  "lvl0" => [
    "Cleaning",
    "Bread"
  ],
  "lvl1" => [
    null,
    "Bread > rolls"
  ]
];

$lvl1 = array_filter($categories['lvl1'], function($value) {
    return !empty($value);
});

var_dump($lvl1);

That will return:

array(1) {
  [1] =>
  string(13) "Bread > rolls"
}

Answer 2

I was having the same issue on my last working day.Generally for associative array array_filter() needs the array key to filter out null , false etc values. But this small function help me to filter out NULL values without knowing the associative array key. Hope this will also help you, https://eval.in/881229

Code:

function array_filter_recursive($input)
  {
    foreach ($input as &$value)
    {
      if (is_array($value))
      {
        $value = array_filter_recursive($value);
      }
    }

    return array_filter($input);
  } 

$categories = [
  "lvl0" => [
    "Cleaning",
    "Bread"
  ],
  "lvl1" => [
    null,
    "Bread > rolls"
  ]
];

$result = array_filter_recursive($categories);
print '<pre>';
print_r($result);
print '</pre>';

Output:

(
    [lvl0] => Array
        (
            [0] => Cleaning
            [1] => Bread
        )

    [lvl1] => Array
        (
            [1] => Bread > rolls
        )

)

Ref: http://php.net/manual/en/function.array-filter.php#87581

Answer 3

Robbie Averill在以下内容中对我的帖子进行了评论，从而解决了该问题：

$categories['lvl1'] = array_filter($categories['lvl1']);