Decoding multiple JSON objects in PHP

Question

I'm using PHP sockets for managing data in a chat application, here's a sample JSON string I'm expecting from the socket read :

{ "m_time" : "2015-04-07 11:37:35", "id" : "29", "msg" : "Hai there. This is a test message"}

But sometimes in the socket reads multiple objects concatenated, like this :

{ "m_time" : "2015-04-07 11:37:35", "id" : "30", "msg" : "Hai there 1"}{ "m_time" : "2015-04-07 11:37:36", "id" : "31", "msg" : "Hai there 2"}{ "m_time" : "2015-04-07 11:37:37", "id" : "32", "msg" : "Hai there 3"}

How can I json_decode no matter if there's a single object or multiple ones ?

PHP Code for Socket read:

while(@socket_recv($changed_socket, $buf, READ_SIZE, 0) >= 1)
{
    if(!$buf) logResponse('Socket Read Failed for '. $changed_socket);

    $received_text = $buf; //unmask data
    $tst_msg = json_decode($received_text); //json decode 

    logResponse('Received Data: '. $received_text);
}
// logResponse() is used to write a log file log.html

The socket is not returning a valid JSON string in the case of multiple objects. If you want to use json_decode, this issue should be solved either by changing the socket code (preferred) or by manipulating the output you get: you need commas between }{ and you need [] at the beginning and at the end of the result. You can check JSON validity here: jsonlint.com — Danilo
– Danilo, Commented Apr 7, 2015 at 6:55

shawn · Accepted Answer · 2022-12-09 11:13:05Z

6

tidy your input, add commas after every json string, send like this:

{ "m_time" : "2015-04-07 11:37:35", "id" : "30", "msg" : "Hai there 1"},{ "m_time" : "2015-04-07 11:37:36", "id" : "31", "msg" : "Hai there 2"},{ "m_time" : "2015-04-07 11:37:37", "id" : "32", "msg" : "Hai there 3"},

php function

function json_decode_multi($s, $assoc = false, $depth = 512, $options = 0) {
    if(substr($s, -1) == ',')
        $s = substr($s, 0, -1);
    return json_decode("[$s]", $assoc, $depth, $options);
}

var_dump(json_decode_multi('{ "m_time" : "2015-04-07 11:37:35", "id" : "30", "msg" : "Hai there 1"},{ "m_time" : "2015-04-07 11:37:36", "id" : "31", "msg" : "Hai there 2"},{ "m_time" : "2015-04-07 11:37:37", "id" : "32", "msg" : "Hai there 3"},'));

output:

array(3) {
  [0] =>
  class stdClass#1 (3) {
    public $m_time =>
    string(19) "2015-04-07 11:37:35"
    public $id =>
    string(2) "30"
    public $msg =>
    string(11) "Hai there 1"
  }
  [1] =>
  class stdClass#2 (3) {
    public $m_time =>
    string(19) "2015-04-07 11:37:36"
    public $id =>
    string(2) "31"
    public $msg =>
    string(11) "Hai there 2"
  }
  [2] =>
  class stdClass#3 (3) {
    public $m_time =>
    string(19) "2015-04-07 11:37:37"
    public $id =>
    string(2) "32"
    public $msg =>
    string(11) "Hai there 3"
  }
}

Keep in mind: the protocol design is not stable. @socket_recv($changed_socket, $buf, READ_SIZE, 0) may read half a string(broken) if it meets max READ_SIZE. If the data decoding failed, you should keep the last received data, and read more data to append to it and retry.

edited Dec 9, 2022 at 11:13

answered Apr 7, 2015 at 6:59

shawn

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1 Comment

shawn Over a year ago

it should work. but i think your protocol design is not stable. @socket_recv($changed_socket, $buf, READ_SIZE, 0) may read half a string(broken) if it meets max READ_SIZE. if the data decoding failed, you should keep the last received data, and read more data to append to it and retry.

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