Php: How to echo json_encode as soon as it gets generated

Question

For a rest API, I need to serialize big and deeply nested json objects;

Is there a way to echo the json while it is generated?

If I echo json_encode($var) , it will generate the whole json and then spit it out: it costs memory, and I have to wait for the whole generation to be complete, before I start to see some response in my browser.

Is there any way to force json_decode to have this kind of behaviour?

Or are there libraries that can do this kind of stuff?

No. Unless you want to roll your own encoder. a JSON-encoded data structure of any reasonable amount of complexity is going to be a huge mess of nested `[ ... ]` and `{ .... }` pairs. outputting on the go is possible, but you're highly likely to end up with partial/corrupt strings at the other end, especially if the encoding process causes an OOM condition or whatever. — Marc B, Aug 01 '14 at 16:12

score 0 · Answer 1 · answered Aug 01 '14 at 16:28

Your only option is to iterate over the object you are encoding and to encode it item by item, probably writing your own json notation to contain the generated json.

For example

echo "["; // or { for an associative array (don't forget to output the json_encode()d keys and their colons)
$first = true;
for ($i = 0; $i < 10000000; $i++) {
    // json does not support trailing commas like php does
    // and you can't do an implode(",", $array) here because of the memory usage
    if ($first) {
        $first = false;
    } else {
        echo ",";
    }
    echo json_encode($i);
}
echo "]"; // or }

taken from here: http://forums.phpfreaks.com/topic/288266-json-encode-exceeds-allowed-memory/

score -2 · Answer 2 · edited May 23 '17 at 10:30

-2

You can use smarty template to put json just reading file from disk. Or you can check this https://stackoverflow.com/a/4820537/3900160

edited May 23 '17 at 10:30

Community

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1

answered Aug 01 '14 at 16:16

Ugur KAZDAL

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You can improve this answer by giving an explicit example about how to use "smarty template" to echo the JSON upon encoding. – drs Aug 01 '14 at 16:29
Are you sure smarty templates are generated on the fly and not stored in memory before being pushed to http? – Davide Orazio Montersino Aug 01 '14 at 16:39

Php: How to echo json_encode as soon as it gets generated

2 Answers2