check if value is json php code example

Example 1: php check if json

function isJson($string) {
 json_decode($string);
 return (json_last_error() == JSON_ERROR_NONE);
}

Example 2: php if is json object

//Simple
if (is_object(json_decode($var))) { 
  ....
}

//Else
var $x = json_decode($var);
var $y = is_object($x)?$x:....;

//Better
function json_validate($string) {
    // decode the JSON data
    $result = json_decode($string);

    // switch and check possible JSON errors
    switch (json_last_error()) {
        case JSON_ERROR_NONE:
            $error = ''; // JSON is valid // No error has occurred
            break;
        case JSON_ERROR_DEPTH:
            $error = 'The maximum stack depth has been exceeded.';
            break;
        case JSON_ERROR_STATE_MISMATCH:
            $error = 'Invalid or malformed JSON.';
            break;
        case JSON_ERROR_CTRL_CHAR:
            $error = 'Control character error, possibly incorrectly encoded.';
            break;
        case JSON_ERROR_SYNTAX:
            $error = 'Syntax error, malformed JSON.';
            break;
        // PHP >= 5.3.3
        case JSON_ERROR_UTF8:
            $error = 'Malformed UTF-8 characters, possibly incorrectly encoded.';
            break;
        // PHP >= 5.5.0
        case JSON_ERROR_RECURSION:
            $error = 'One or more recursive references in the value to be encoded.';
            break;
        // PHP >= 5.5.0
        case JSON_ERROR_INF_OR_NAN:
            $error = 'One or more NAN or INF values in the value to be encoded.';
            break;
        case JSON_ERROR_UNSUPPORTED_TYPE:
            $error = 'A value of a type that cannot be encoded was given.';
            break;
        default:
            $error = 'Unknown JSON error occured.';
            break;
    }

    if ($error !== '') {
        // throw the Exception or exit // or whatever :)
        exit($error);
    }
    // everything is OK
    return $result;
}
$output = json_validate($json);

Example 3: php is json

function is_json($input_line) {
    if(is_string($input_line)){
        preg_match('/^\{(\s+|\n+)*(\"(.*)(\n+|\s+)*)*\}$|^\[(\s+|\n+)*\{(\s+|\n+)*(\"(.*)(\n+|\s+)*)*\}(\s+|\n)*\]$/', $input_line, $output_array);
        if (  isset($output_array) || !empty($output_array)) {
            return true;
        }
    }
    return false;
    }