PHP - replace values in sub array - php

Question

I have two arrays $pq and $rs. please see them below:
$pq = array ('page-0'=>array ('line-0'=>array('item-0'=>array('name'=>"item-00",'value'=>"123"),
'item-1'=>array('name'=>"item-01",'value'=>"456")
),
'line-1'=>array('item-0'=>array('name'=>"item-10",'value'=>"789"),
'item-1'=>array('name'=>"item-11",'value'=>"012")
)),
'page-1'=>array ('line-0'=>array('item-0'=>array('name'=>"item-100",'value'=>"345"),
'item-1'=>array('name'=>"item-101",'value'=>"678")
),
'line-1'=>array('item-0'=>array('name'=>"item-110",'value'=>"901"),
'item-1'=>array('name'=>"item-111",'value'=>"234")
),
'line-2'=>array('item-0'=>array('name'=>"item-210",'value'=>"567"),
'item-1'=>array('name'=>"item-211",'value'=>"890")
))
);
$rs = array ('1'=>array('name'=>'item-00', 'value'=>"abc"),
'2'=>array('name'=>'item-01', 'value'=>"def"),
'3'=>array('name'=>'item-10', 'value'=>"ghi"),
'4'=>array('name'=>'item-11', 'value'=>"jkl"),
'5'=>array('name'=>'item-100', 'value'=>"mno"),
'6'=>array('name'=>'item-101', 'value'=>"pqr"),
'7'=>array('name'=>'item-110', 'value'=>"stu"),
'8'=>array('name'=>'item-111', 'value'=>"vwx")
);
What I am trying to do is to replace the values in $pq for items with the values from $rs.
for example item-01 in $pa to be replaced with abc from $rs.
What I tried is this:
foreach($rs as &$rs1) {
echo "first count :".$firstCount."<br>";
foreach($pq as $pages) {
foreach($pages as $lines) {
foreach($lines as &$item) {
if ($item['name'] == $rs1['name']) { echo "matching </p>";
$item['value']=$rs1['value'];
echo '<pre>';
print_r($item);
echo '</pre>';
echo "<hr>";
}
}
}
}
}
When I print the values of $item from $pq, it prints the values from $rs, but when I print the whole array $pq, the values seem to be unchanged.
Can anyone please help me find out what I am missing ?

Answer 1

You're correctly looping through the items in each line by reference, but you're not doing it for the lines or pages themselves. So you're updating the value of an item in a copy of the line, instead of the line itself. It should be:
foreach($rs as $rs1) {
echo "first count :".$firstCount."<br>";
foreach($pq as &$pages) {
foreach($pages as &$lines) {
foreach($lines as &$item) {
if ($item['name'] == $rs1['name']) { echo "matching </p>";
$item['value']=$rs1['value'];
echo '<pre>';
print_r($item);
echo '</pre>';
echo "<hr>";
}
}
}
}
}
Note that the & in front of &$lines and &$pages. Note also that $rs1 doesn't need to be passed by reference, since you aren't changing anything in that array.

Answer 2

You’ve assigned $item by reference but haven’t done the same for $pages and $lines. There will be no effect on the actual values of $pq unless you assign $pages by reference; similarly, the actual values of $pages will remain unchanged unless you assign $lines by reference. Therefore, in order to achieve what you want, change foreach($pq as $pages) to foreach($pq as &$pages) and foreach($pages as $lines) to foreach($pages as &$lines).

Answer 3

You can build a search array first so that you can match items easier:
$search = array_reduce($rs, function(&$prev, $current) {
$prev[$current['name']] = $current;
return $prev;
}, []);
This creates another array with the item name as the key. Then, you iterate over each item in $pq and modify the leaves where necessary:
foreach ($pq as &$page_data) {
foreach ($page_data as &$line_data) {
foreach ($line_data as &$item_data) {
if (isset($search[$item_data['name']])) {
$item_data = $search[$item_data['name']];
}
}
}
}
Make sure to use references at each level of iteration.