PHP preg_replace是JSON内容的一部分

I've got the following JSON string:

{
    "time":"321321545646",
    "documents":[
        {"name":"name1","body":"HASH_BASE64 1"},
        {"name":"name2","body":"HASH_BASE64 2"}
    ]
}

In real production use, the "HASH BASE64" will be base64 encoded string. How can I replace content of each "body" tag with string = "LONGSTRING", to receive something like this:

{
    "time":"321321545646",
    "documents":[
        {"name":"name1","body":"LONGSTRING"},
        {"name":"name2","body":"LONGSTRING"}
    ]
}

?

You probably shouldn't do it with regular expressions but by decoding, changing the data and encoding again:

$data = json_decode($json);

for($i = 0; $i < count($data->documents); $i++) {
    $data->documents[$i]->body = "LONGSTRING";
}

$json = json_encode($data);

You shouldn't use regular expressions to modify JSON data - PHP has native functions for parsing and encoding it. See http://php.net/manual/en/ref.json.php

<?php
$json = '{
    "time":"321321545646",
    "documents":[
        {"name":"name1","body":"HASH_BASE64 1"},
        {"name":"name2","body":"HASH_BASE64 2"}
    ]
}';

// Decode JSON into a native PHP object structure
$decoded = json_decode($json);

// Loop over each element, and modify the body
$decoded->documents = array_map(function ($document) {
    $document->body = 'LONGSTRING';
    return $document;
}, $decoded->documents);

// Re-encode
echo json_encode($decoded);

You Don't Need preg-replace() Just Decode Your json by json_decode()

Then Loop Through The json Document And change Each Document data Like So:

$json = json_decode('{
    "time":"321321545646",
    "documents":[
        {"name":"name1","body":"HASH_BASE64 1"},
        {"name":"name2","body":"HASH_BASE64 2"}
    ]
}');
foreach ($json->documents as $document){
    $document->body = "LONGSTRING";
}
dump($json);

This Is The Output :

{#229 ▼
  +"time": "321321545646"
  +"documents": array:2 [▼
    0 => {#228 ▼
      +"name": "name1"
      +"body": "LONGSTRING"
    }
    1 => {#227 ▼
      +"name": "name2"
      +"body": "LONGSTRING"
    }
  ]
}