Decoding Json String From Javascript in PHP

Question

I have the following json sent (POST) from my javascript to the php

function boardToJSON() {
    return JSON.stringify({
        "pieces" : gPieces,          // gpieces and gdestinations is an array
        "destinations" : gDestinations,
        "boardSize" : kBoardHeight        // boardSize is an integer value 9

    });

// Below function is called on Button Click and url contains PATH to the php file.

function makeMove() {
    var move;
    $.ajax({
        type: 'POST',
        url: url,
        contentType: "application/json",
        dataType: "json",
        async: false,
        data: boardToJSON(),
        success: function(msg) {
            move = msg;     
        },
        error: function(jqXHR, exception) {
            if (jqXHR.status === 0) {
                alert('Unable to connect.\n Verify Network.');
            } else if (jqXHR.status == 404) {
                alert('Requested URL of HalmaAI not found. [404]');
            } else if (jqXHR.status == 500) {
                alert('Internal Server Error [500].');
            } else if (exception === 'parsererror') {
                alert('Data from HalmaAI was not JSON :( Parse failed.');
            } else if (exception === 'timeout') {
                alert('Time out error.');
            } else if (exception === 'abort') {
                alert('Ajax request aborted.');
            } else {
                alert('Uncaught Error.\n' + jqXHR.responseText);
            }
        }

    });

On the server side (in PHP) I am trying to get it like this

$jsonString = file_get_contents("php://input");
$myJson = json_decode($jsonString);

echo $myJson["boardSize"];   // also tried  $myJson.boardSize etc

Issue is that I am unable to decode JSON in PHP. Can someone guide me here please ? Thanks

I don't get it. You say you're posting the JSON, but the PHP you show is attempting to load the JSON from a file, not receive it from POST. — Mitya
– Mitya, Commented Oct 21, 2014 at 20:12
@AbraCadaver because the entire $_POST superglobal is not json_encoded; only a child element in that array can be. — Patrick Moore
– Patrick Moore, Commented Oct 21, 2014 at 20:18
@SetSailMedia $_POST doesn't come into play here. He is trying to read JSON from PHP raw input. — Mike Brant
– Mike Brant, Commented Oct 21, 2014 at 20:21

Mike Brant · Accepted Answer · 2014-10-21 20:31:07Z

1

You should set the contentType property on AJAX request to application/json. This will set proper header on request such that server will not attempt to populate $_POST in favor of you working with the raw input.

function makeMove() {
    var move;
    $.ajax({
        type: 'POST',
        url: url,
        contentType: "application/json"
        dataType: "json",
        async: false,
        data: boardToJSON(),
        success: function(msg) {
            move = msg;     
        }
    });
}

Assuming this works, you can access the boardSize property at:

$myJson->boardSize;

The other problem you have is that since you specify dataType: "json" you need to make sure you send back valid JSON, which you currently are not.

This is not valid JSON:

echo $myJson["boardSize"];

This would be (of course this is a trivial example):

$returnObj = new stdClass();
$returnObj->boardSize = $myJson->boardSize;
echo json_encode($returnObj);

edited Oct 21, 2014 at 20:31

answered Oct 21, 2014 at 20:25

Mike Brant

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10 Comments

farhangdon Over a year ago

Now how can I get value of boardSize on the server side ??

farhangdon Over a year ago

No it says the data returned is not Json.

farhangdon Over a year ago

On Server Side I am going this. $jsonString = file_get_contents("php://input"); $myJson = json_decode($jsonString); $returnObj = new stdClass(); $returnObj->boardSize = $myJson->boardSize; echo json_encode($returnObj);

Mike Brant Over a year ago

@farhangdon And what result do you get?

farhangdon Over a year ago

Json returned in Not Valid .

|

Efog · Accepted Answer · 2014-10-21 20:29:06Z

0

If you want decode json to array in PHP, you should set the 2nd argument of json_decode to true.
Example:

$jsonString = file_get_contents("php://input");
$myJson = json_decode($jsonString, true);
echo $myJson["boardSize"];

answered Oct 21, 2014 at 20:29

Efog

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