[php] PHP json_decode() returns NULL with valid JSON?

I have this JSON object stored on a plain text file:

{
    "MySQL": {
        "Server": "(server)",
        "Username": "(user)",
        "Password": "(pwd)",
        "DatabaseName": "(dbname)"
    },
    "Ftp": {
        "Server": "(server)",
        "Username": "(user)",
        "Password": "(pwd)",
        "RootFolder": "(rf)"
    },
    "BasePath": "../../bin/",
    "NotesAppPath": "notas",
    "SearchAppPath": "buscar",
    "BaseUrl": "http:\/\/montemaiztusitio.com.ar",
    "InitialExtensions": [
        "nem.mysqlhandler",
        "nem.string",
        "nem.colour",
        "nem.filesystem",
        "nem.rss",
        "nem.date",
        "nem.template",
        "nem.media",
        "nem.measuring",
        "nem.weather",
        "nem.currency"
    ],
    "MediaPath": "media",
    "MediaGalleriesTable": "journal_media_galleries",
    "MediaTable": "journal_media",
    "Journal": {
        "AllowedAdFileFormats": [
            "flv:1",
            "jpg:2",
            "gif:3",
            "png:4",
            "swf:5"
        ],
        "AdColumnId": "3",
        "RSSLinkFormat": "%DOMAIN%\/notas\/%YEAR%-%MONTH%-%DAY%\/%TITLE%/",
        "FrontendLayout": "Flat",
        "AdPath": "ad",
        "SiteTitle": "Monte Maíz: Tu Sitio",
        "GlobalSiteDescription": "Periódico local de Monte Maíz.",
        "MoreInfoAt": "Más información aquí, en el Periódico local de Monte Maíz.",
        "TemplatePath": "templates",
        "WeatherSource": "accuweather:SAM|AR|AR005|MONTE MAIZ",
        "WeatherMeasureType": "1",
        "CurrencySource": "cotizacion-monedas:Dolar|Euro|Real",
        "TimesSingular": "vez",
        "TimesPlural": "veces"
    }
}

When I try to decode it with json_decode(), it returns NULL. Why? The file is readable (I tried echoing file_get_contents() and it worked ok).

I've tested JSON against http://jsonlint.com/ and it's perfectly valid.

What's wrong here?

Solution

Looking for answers on Google, I got back to SO: json_decode returns NULL after webservice call. My JSON file had the UTF BOM sequence (some binary chars that shouldn't be there), thus, breaking the JSON structure. Went to Hex Editor, erased the bytes. Everything's back to normal. Why has this happened? Because I edited the file using Microsoft Windows' Notepad. Terrible idea!

If you are getting json from database, put

mysqli_set_charset($con, "utf8");

after defining connection link $con

you should ensure these points

1. your json string dont have any unknowns characters

2. json string can view from online json viewer (you can search on google as online viewer or parser for json) it should view without any error

3. your string dont have html entities it should be plain text/string

for explanation of point 3

$html_product_sizes_json=htmlentities($html);
    $ProductSizesArr = json_decode($html_product_sizes_json,true);

to (remove htmlentities() function )

$html_product_sizes_json=$html;
    $ProductSizesArr = json_decode($html_product_sizes_json,true);

• I also face the same issue...
• I fix the following steps... 1) I print that variable in browser 2) Validate that variable data by freeformatter 3) copy/refer that data in further processing
• after that, I didn't get any issue.

This worked for me

json_decode( preg_replace('/[\x00-\x1F\x80-\xFF]/', '', $json_string), true );

If you check the the request in chrome you will see that the JSON is text, so there has been blank code added to the JSON.

You can clear it by using

$k=preg_replace('/\s+/', '',$k);

Then you can use:

json_decode($k)

print_r will then show the array.

It took me like an hour to figure it out, but trailing commas (which work in JavaScript) fail in PHP.
This is what fixed it for me:

str_replace([PHP_EOL, ",}"], ["", "}"], $JSON);

Just save some one time. I spent 3 hours to find out that it was just html encoding problem. Try this

if(get_magic_quotes_gpc()){
   $param = stripslashes($row['your column name']);
}else{
  $param = $row['your column name'];
}

$param = json_decode(html_entity_decode($param),true);
$json_errors = array(
JSON_ERROR_NONE => 'No error has occurred',
JSON_ERROR_DEPTH => 'The maximum stack depth has been exceeded',
JSON_ERROR_CTRL_CHAR => 'Control character error, possibly incorrectly encoded',
JSON_ERROR_SYNTAX => 'Syntax error',
);
echo 'Last error : ', $json_errors[json_last_error()], PHP_EOL, PHP_EOL;
print_r($param);

The most important thing to remember, when you get a NULL result from JSON data that is valid is to use the following command:

json_last_error_msg();

Ie.

var_dump(json_last_error_msg());
string(53) "Control character error, possibly incorrectly encoded"

You then fix that with:

$new_json = preg_replace('/[[:cntrl:]]/', '', $json);

$k=preg_replace('/\s+/', '',$k); 

did it for me. And yes, testing on Chrome. Thx to user2254008

As stated by Jürgen Math using the preg_replace method listed by user2254008 fixed it for me as well.

This is not limited to Chrome, it appears to be a character set conversion issue (at least in my case, Unicode -> UTF8) This fixed all the issues i was having.

As a future node, the JSON Object i was decoding came from Python's json.dumps function. This in turn caused some other unsanitary data to make it across though it was easily dealt with.

this help you to understand what is the type of error

<?php
// A valid json string
$json[] = '{"Organization": "PHP Documentation Team"}';

// An invalid json string which will cause an syntax 
// error, in this case we used ' instead of " for quotation
$json[] = "{'Organization': 'PHP Documentation Team'}";


foreach ($json as $string) {
    echo 'Decoding: ' . $string;
    json_decode($string);

    switch (json_last_error()) {
        case JSON_ERROR_NONE:
            echo ' - No errors';
        break;
        case JSON_ERROR_DEPTH:
            echo ' - Maximum stack depth exceeded';
        break;
        case JSON_ERROR_STATE_MISMATCH:
            echo ' - Underflow or the modes mismatch';
        break;
        case JSON_ERROR_CTRL_CHAR:
            echo ' - Unexpected control character found';
        break;
        case JSON_ERROR_SYNTAX:
            echo ' - Syntax error, malformed JSON';
        break;
        case JSON_ERROR_UTF8:
            echo ' - Malformed UTF-8 characters, possibly incorrectly encoded';
        break;
        default:
            echo ' - Unknown error';
        break;
    }

    echo PHP_EOL;
}
?>

I recommend creating a .json file (ex: config.json). Then paste all of your json object and format it. And thus you will be able to remove all of that things that is breaking your json-object, and get clean copy-paste json-object.

For me, I had to turn off the error_reporting, to get json_decode() working correctly. It sounds weird, but true in my case. Because there is some notice printed between the JSON string that I am trying to decode.

So, html_entity_decode() worked for me. Please try this.

$input = file_get_contents("php://input");
$input = html_entity_decode($input);
$event_json = json_decode($input,true);

Just thought I'd add this, as I ran into this issue today. If there is any string padding surrounding your JSON string, json_decode will return NULL.

If you're pulling the JSON from a source other than a PHP variable, it would be wise to "trim" it first:

$jsonData = trim($jsonData);

Here is here I solved mine https://stackoverflow.com/questions/17219916/64923728 .. The JSON file has to be in UTF-8 Encoding mine was in UTF-8 with BOM which was adding a weird &65279; to the json string output causing json_decode() to return null

I've solved this issue by printing the JSON, and then checking the page source (CTRL/CMD + U):

print_r(file_get_contents($url));

Turned out there was a trailing <pre> tag.

I had the same problem and I solved it simply by replacing the quote character before decode.

$json = str_replace('"', '"', $json);
$object = json_decode($json);

My JSON value was generated by JSON.stringify function.

Here you can find little JSON wrapper with corrective actions that addresses BOM and non-ASCI issue: https://stackoverflow.com/a/43694325/2254935

Maybe some hidden characters are messing with your json, try this:

$json = utf8_encode($yourString);
$data = json_decode($json);

<?php 
$json_url = "http://api.testmagazine.com/test.php?type=menu";
$json = file_get_contents($json_url);
$json=str_replace('},

]',"}

]",$json);
$data = json_decode($json);

echo "<pre>";
print_r($data);
echo "</pre>";
?>

For my case, it's because of the single quote in JSON string.

JSON format only accepts double-quotes for keys and string values.

Example:

$jsonString = '{\'hello\': \'PHP\'}'; // valid value should be '{"hello": "PHP"}'
$json = json_decode($jsonString);
print $json; // null

I got this confused because of Javascript syntax. In Javascript, of course, we can do like this:

let json = {
    hello: 'PHP' // no quote for key, single quote for string value
}

// OR:
json = {
    'hello': 'PHP' // single quote for key and value
}

but later when convert those objects to JSON string:

JSON.stringify(json); // "{"hello":"PHP"}"

You could try with it.

json_decode(stripslashes($_POST['data']))