PHP update json from received input and write back to same file - php

Question

I have a json file stored on server & it looks like below:
{
"support_link":"#",
"support_link_2":"#",
"packs":[
{
"identifier":1,
"viewCount":0,
"downloadCount":0
},
{
"identifier":2,
"viewCount":0,
"downloadCount":0
}
]
}
By using PHP, I want to update the viewCount & downloadCount of some of the arrays inside packs.
But the thing is the data is received via a POST method to the server which contains another json with info. of which identifier to update & what param to update, & I am not able to update the existing file & save it back.
Received Json format:
{
"impressions": [
{
"identifier": "1",
"impressionCount": 2
},
{
"identifier": "100",
"impressionCount": 2
},
{
"identifier": "1000",
"impressionCount": 2000
}
],
"downloads": [
{
"identifier": "1",
"downloadCount": 10
}
]
}
What I've tried to do so far:
$json = file_get_contents('php://input');
if ($json != '') {
$properJsonFormatted = json_decode($json, true);
$impressions = $properJsonFormatted['impressions'];
$downloads = $properJsonFormatted['downloads'];
$testConfig =
$json = file_get_contents('php://input');
if ($json != '') {
$properJsonFormatted = json_decode($json, true);
$impressions = $properJsonFormatted['impressions'];
$downloads = $properJsonFormatted['downloads'];
$testConfig = json_decode(file_get_contents("test_config.json"),true);
$packs = $testConfig['packs'];
foreach ($packs as &$pack) {
$packIdentifier = $pack['identifier'];
foreach ($impressions as $impression) {
$impressionIdentifier = $impression['identifier'];
if ($packIdentifier == $impressionIdentifier) {
$pack['viewCount'] += $impression['impressionCount'];
$newCount = $pack['viewCount'];
print("Id: $packIdentifier, ViewCount: $newCount\n");
}
}
}
put_file_contents("test_config.json" , $testConfig);
// print_r($testConfig);
// Save back the updated test_config.json
}
}

Answer 1

UPDATE
Seem to have misinterpreted the question. The actual problem seems to be much simpler.
Change this:
put_file_contents("test_config.json" , $testConfig);
To this:
file_put_contents('test_config.json', json_encode($testConfig));
Also change this:
$packs = $testConfig['packs'];
To this:
$packs = &$testConfig['packs'];
As it seems you forgot to assign that by reference, while you correctly did that in the foreach.