Custom keys in json_encode array - php

Question

I'm retriving data from mysql. in my php I've got 2 arrays set
$main =array(); //tostore retrived data
$list =array('instock' => 'output1', 'item' => 'output2'); //existing key values and new key value to be replaced
How do I replace the keys with custom keys for each output? exmpale: custom keys output1,output2
current output
[{"instock":"yes", "item":"ch00024"},{..}]
Expected output
[{"output1":"yes", "output2":"ch00024"},{..}]
This is what I have tried so far. But does not work.
$main =array(); //tostore retrived data
$list =array('instock' => 'output1', 'item' => 'output2'); //replace key values
foreach ($result as $key => $value){
$main[ $list[ $key ] ] = $value;
}
echo json_encode( $main );
I get an error Undefined offset: 0. It points to this line $main[ $list[ $key ] ] = $value;
EDIT
This is a screen capture from my console
var_dump():
array(5) {
[0]=>
array(2) {
["instock"]=>
string(3) "yes"
["item"]=>
string(6) "it0215"
}
[1]=>
array(2) {
["instock"]=>
string(3) "yes"
["item"]=>
string(6) "it0381"
}
so on...

Answer 1

Your code works! The issue is in $list array you need define all keys in $result otherwise you need to check if there is that key in $list array.
$result =array(
'instock' => 'yes',
'item' => 'ch00024',
'color' => 'blue',
'price' => 100
);
$main = array();
$list = array('instock' => 'output1', 'item' => 'output2');
foreach ($result as $key => $value){
if (!empty($list[$key])) {
$main[$list[$key]] = $value;
}
}
echo json_encode($main);
Edit
Because you are access 2 dimensional array, so you need an extra loop to go through all items
$result = array(
array (
'instock' => 'yes',
'item' => 'it0215'
),
array(
'instock' => 'yes',
'item' => 'it0381'
)
);
$main = array();
$list = array('instock' => 'output1', 'item' => 'output2');
foreach ($result as $item){
foreach ($item as $key => $value) {
$main[$list[$key]] = $value;
}
}
echo json_encode($main);
The output is
{"output1":"yes","output2":"it0381"}
But In case you want to get all items with key replacement in new array. You should do something like this:
foreach ($result as $index => $item){
foreach ($item as $key => $value) {
$main[$index][$list[$key]] = $value;
}
}
echo json_encode($main);
The output is:
[
{"output1":"yes","output2":"it0215"},
{"output1":"yes","output2":"it0381"}
]

Answer 2

try to this code
$flippedList = array_flip($list);