Decoding json in array , editing array and encoding in json - PHP - php

Question

I am newbee in php and trying to get json in array and wanna change key in that json below is my code :
$json = json_decode(file_get_contents('all_json_files/jobs.json'), true);
foreach ($json as $key=>$row){
foreach ( $row as $key=>$row){
foreach ( $row as $key=>$row){
foreach ($row as $key=>$row){
if(strcmp($key,"security_block")==0)
{
foreach ($row as $k=>$r){
if(strcmp($k,"job_payload_hash")==0)
{
$row[$k]['job_payload_hash']=$base64String;
print_r($row);
}
}
}
}
}
}
}
print_r($json);
Issue is print_r($row); is updating properly but print_r($json); does not print the updated string .

Answer 1

If the key could appear anywhere, the answer is pretty simple:
function update_hash(&$item, $key, $base64String)
{
if ($key == "job_payload_hash") {
$item = $base64String;
}
}
array_walk_recursive($json, 'update_hash', 'something');
Update
The structure is something different that previously assumed; while the above will work, probably the below is a more direct approach:
foreach (array_keys($json['jobs']) as $jobId) {
$json['jobs'][$jobId]['job']['security_block']['job_payload_hash'] = 'something';
}

Answer 2

You use $key & $row variable in multiple time. for this reason, value of $key is changed each time, so parent loop does not work..
You can use recursive function lik answer of #Ja͢ck .

Answer 3

this is because you have to save not in variables you defined after => in a foreach.
You have to store this in format:
$json[0][0] ... = $base64String;
OR
You have to add a new array like $result = array() before you write the foreach and then store it in $result.

Answer 4

Decode the JSON string using json_decode(), edit your resulting array, then use json_encode(); to return the array to a JSON encoded string.
Also, use array_key_exists() rather than comparing array key strings.
$array = json_decode($json);
if(array_key_exists("job_payload_hash", $array){
$array["job_payload_hash"] = base64encode($var);
}
$json = json_encode($array);