php - 在 PHP 中更改关联数组中的键

Question

假设我有一个这样的数组：

array(2) {
  [0]=> array(2) {
    ["n"]=> string(4) "john"
    ["l"]=> string(3) "red"
  }
  [1]=> array(2) {
    ["n"]=> string(5) "nicel"
    ["l"]=> string(4) "blue"
  }
}

我将如何更改内部数组的键？比如说，我想将“n”更改为“name”，将“l”更改为“last_name”。考虑到它可能发生，而不是数组没有特定的键。

Answer 1

使用 array_walk

array_walk($array, function (& $item) {
   $item['new_key'] = $item['old_key'];
   unset($item['old_key']);
});

Answer 2

可能是这样的：

if (isset($array['n'])) {
    $array['name'] = $array['n'];
    unset($array['n']);
}

注意：此解决方案将更改键的顺序。要保留顺序，您必须重新创建数组。

Answer 3

你可以有：

1. 映射密钥交换的数组（使过程参数化）
2. 循环处理原始数组，通过引用访问每个数组项

例如：

$array = array( array('n'=>'john','l'=>'red'), array('n'=>'nicel','l'=>'blue') );

$mapKeyArray = array('n'=>'name','l'=>'last_name');

foreach( $array as &$item )
{
    foreach( $mapKeyArray as $key => $replace )
    {
        if (key_exists($key,$item))
        {
            $item[$replace] = $item[$key];
            unset($item[$key]); 
        }
    }
}

通过这种方式，您可以简单地向$mapKeyArray变量添加几个键/值来进行其他替换。

如果原始数组中没有某些键，此解决方案也有效

Answer 4

只需记下旧值，使用unset将其从数组中删除，然后将其与新键和旧值对一起添加。

Answer 5

重命名键并保持顺序一致（后者对于编写以下代码的用例很重要）。

<?php
/**
 * Rename a key and preserve the key ordering.
 *
 * An E_USER_WARNING is thrown if there is an problem.
 *
 * @param array &$data The data.
 * @param string $oldKey The old key.
 * @param string $newKey The new key.
 * @param bool $ignoreMissing Don't raise an error if the $oldKey does not exist.
 * @param bool $replaceExisting Don't raise an error if the $newKey already exists.
 *
 * @return bool True if the rename was successful or False if the old key cannot be found or the new key already exists.
 */
function renameKey(array &$data, $oldKey, $newKey, $ignoreMissing = false, $replaceExisting = false)
{
    if (!empty($data)) {
        if (!array_key_exists($oldKey, $data)) {
            if ($ignoreMissing) {
                return false;
            }

            return !trigger_error('Old key does not exist', E_USER_WARNING);
        } else {
            if (array_key_exists($newKey, $data)) {
                if ($replaceExisting) {
                    unset($data[$newKey]);
                } else {
                    return !trigger_error('New key already exists', E_USER_WARNING);
                }
            }

            $keys = array_keys($data);
            $keys[array_search($oldKey, array_map('strval', $keys))] = $newKey;
            $data = array_combine($keys, $data);

            return true;
        }
    }

    return false;
}

还有一些单元测试（正在使用 PHPUnit，但希望可以理解为测试的目的）。

public function testRenameKey()
{
    $newData = $this->data;
    $this->assertTrue(Arrays::renameKey($newData, 200, 'TwoHundred'));
    $this->assertEquals(
        [
            100 => $this->one,
            'TwoHundred' => $this->two,
            300 => $this->three,
        ],
        $newData
    );
}

public function testRenameKeyWithEmptyData()
{
    $newData = [];
    $this->assertFalse(Arrays::renameKey($newData, 'junk1', 'junk2'));
}

public function testRenameKeyWithExistingNewKey()
{
    Arrays::renameKey($this->data, 200, 200);
    $this->assertError('New key already exists', E_USER_WARNING);
}

public function testRenameKeyWithMissingOldKey()
{
    Arrays::renameKey($this->data, 'Unknown', 'Unknown');
    $this->assertError('Old key does not exist', E_USER_WARNING);
}

public function testRenameKeyWithMixedNumericAndStringIndicies()
{
    $data = [
        'nice', // Index 0
        'car' => 'fast',
        'none', // Index 1
    ];
    $this->assertTrue(Arrays::renameKey($data, 'car', 2));
    $this->assertEquals(
        [
            0 => 'nice',
            2 => 'fast',
            1 => 'none',
        ],
        $data
    );
}

AssertError 断言可用于 PHPUnit，来自https://github.com/digitickets/phpunit-errorhandler

Answer 6

您可以使用array_flip函数：

$original = array('n'=>'john','l'=>'red');
$flipped = array_flip($original);
foreach($flipped as $k => $v){
    $flipped[$k] = ($v === 'n' ? 'name' : ($v === 'l' ? 'last_name' : $v));
}
$correctedOriginal = array_flip($flipped);

Answer 7

function arrayReplaceKey($array, $oldKey, $newKey) {
    $r = array();
    foreach ($array as $k => $v) {
        if ($k === $oldKey) $k = $newKey;
        $r[$k] = $v;
    }
    return $r;
}

Answer 8

这是更改数组键并保持数组内原始位置的解决方案。它适用于关联数组。在我的例子中，这些值是对象，但我已经简化了这个例子。

// Our array
$fields = array(
    'first_name' => 'Radley',
    'last_name' => 'Sustaire',
    'date' => '6/26/2019', // <== Want to rename the key from "date" to "date_db"
    'amazing' => 'yes',
);

// Get the field value
$date_field = $fields['date'];

// Get the key position in the array (numeric)
$key_position = array_search( 'date', array_keys($fields) );

// Remove the original value
unset($fields['date']);

// Add the new value back in, with the new key, at the old position
$fields = array_merge(
    array_slice( $fields, 0, $key_position, true ),
    array( 'date_db' => $date_field ), // Notice the new key ends with "_db"
    array_slice( $fields, $key_position, null, true )
);

/*
Input:
Array(
    [first_name] => Radley
    [last_name] => Sustaire
    [date] => 6/26/2019
    [amazing] => yes
)

Output:
Array(
    [first_name] => Radley
    [last_name] => Sustaire
    [date_db] => 6/26/2019
    [amazing] => yes
)
*/

Answer 9

通过引用传递

foreach($arr as &$m)
{
  $m['first_name'] = $m['n'];
  $m['last_name'] = $m['l'];
  unset($m['l'], m['n']);
}

print_r($arr);