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Parsing JSON using php jsonpath

Posted by: admin July 12, 2020 Leave a comment

Questions:

I’m trying to parse a JSON in PHP using jsonpath ….

My JSON is coming from this

https://servizionline.sanita.fvg.it/tempiAttesaService/tempiAttesaPs

(it’s quite too long to cut/paste here but you can see it in a browser session ….)

The JSON is a valid JSON (I’ve verified it using https://jsonlint.com/ … ).

I’ve tried the jsonpath expression using http://www.jsonquerytool.com/ and all seems works fine, but when I put all in my PHP code sample below ….

<?php  
    ini_set('display_errors', 'On');
    error_reporting(E_ALL);

    require_once('json.php');      // JSON parser
    require_once('jsonpath-0.8.0.php');  // JSONPath evaluator

    $url = 'https://servizionline.sanita.fvg.it/tempiAttesaService/tempiAttesaPs';

    $ch = curl_init();
    curl_setopt($ch, CURLOPT_AUTOREFERER, TRUE);
    curl_setopt($ch, CURLOPT_HEADER, 0);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_FOLLOWLOCATION, TRUE);
    curl_setopt($ch, CURLOPT_PROXY, '');
    $data = curl_exec($ch);
    curl_close($ch);

    $parser = new Services_JSON(SERVICES_JSON_LOOSE_TYPE);
    $o = $parser->decode($data);

    $xpath_for_parsing = '$..aziende[?(@.descrizione=="A.S.U.I. - Trieste")]..prontoSoccorsi[?(@.descrizione=="Pronto Soccorso e Terapia Urgenza Trieste")]..dipartimenti[?(@.descrizione=="Pronto Soccorso Maggiore")]..codiciColore[?(@.descrizione=="Bianco")]..situazionePazienti..numeroPazientiInAttesa';

    $match1 = jsonPath($o, $xpath_for_parsing);
    //print_r($match1);
    $match1_encoded = $parser->encode($match1);
    print_r($match1_encoded);

    $match1_decoded = json_decode($match1_encoded);

    //print_r($match1_decoded);

    if ($match1_decoded[0] != '') {
     return  $match1_decoded[0];
    }
    else {
     return  "N.D.";
   } 
?>

… no values are printed .. only a “false” value.

Something goes wrong in my jsonpath expression when I put it in my PHP code: ths error that coming out is the follow

Warning: Missing argument 3 for JsonPath::evalx(), called in /var/www/html/OpenProntoSoccorso/Test/jsonpath-0.8.0.php on line 84 and defined in /var/www/html/OpenProntoSoccorso/Test/jsonpath-0.8.0.php on line 101

Notice: Use of undefined constant descrizione - assumed 'descrizione' in /var/www/html/OpenProntoSoccorso/Test/jsonpath-0.8.0.php(104) : eval()'d code on line 1

Probably I’ve to escape / quoting my jsonpath to use it in PHP but I don’t know how … any suggestion is appreciated …

NOTE: I need to use jsonpath expressions like ?(@.descrizione=="A.S.U.I. - Trieste") and I can’t use “positional” json path …

I’ve also tried to use jsonpath-0.8.3.php coming from here https://github.com/ITS-UofIowa/jsonpath/blob/master/jsonpath.php, but nothing change …

Suggestions?

Thank you in advance …

How to&Answers:

you can use json_decode to convert it to a native php array, then you can use hhb_xml_encode ( from https://stackoverflow.com/a/43697765/1067003 ) to convert the array to an xml, then you can use DOMDocument::loadHTML to convert the XML to a DOMDocument, then you can use DOMXPath::query to search through it with XPaths…

example:

<?php
declare(strict_types = 1);
header ( "content-type: text/plain;charset=utf8" );
require_once ('hhb_.inc.php');
$json_raw = (new hhb_curl ( '', true ))->exec ( 'https://servizionline.sanita.fvg.it/tempiAttesaService/tempiAttesaPs' )->getStdOut ();
$parsed = json_decode ( $json_raw, true );
// var_dump ( $parsed );
$xml = hhb_xml_encode ( $parsed );
// var_dump($xml);
$dom = @DOMDocument::loadHTML ( $xml );
$dom->formatOutput = true;
$xp = new DOMXPath ( $dom );
$elements_for_parsing = $xp->query ( '//aziende/descrizione[text()=' . xpath_quote ( 'A.S.U.I. - Trieste' ) . ']|//prontosoccorsi/descrizione[text()=' . xpath_quote ( 'Pronto Soccorso e Terapia Urgenza Trieste' ) . ']|//dipartimenti/descrizione[text()=' . xpath_quote ( 'Pronto Soccorso Maggiore' ) . ']|//codicicolore/descrizione[text()=' . xpath_quote ( 'Bianco' ) . ']|//situazionepazienti|//numeroPazientiInAttesa' );
// var_dump ( $elements_for_parsing,$dom->saveXML() );
foreach ( $elements_for_parsing as $ele ) {
    var_dump ( $ele->textContent );
}

// based on https://stackoverflow.com/a/1352556/1067003
function xpath_quote(string $value): string {
    if (false === strpos ( $value, '"' )) {
        return '"' . $value . '"';
    }
    if (false === strpos ( $value, '\'' )) {
        return '\'' . $value . '\'';
    }
    // if the value contains both single and double quotes, construct an
    // expression that concatenates all non-double-quote substrings with
    // the quotes, e.g.:
    //
    // concat("'foo'", '"', "bar")
    $sb = 'concat(';
    $substrings = explode ( '"', $value );
    for($i = 0; $i < count ( $substrings ); ++ $i) {
        $needComma = ($i > 0);
        if ($substrings [$i] !== '') {
            if ($i > 0) {
                $sb .= ', ';
            }
            $sb .= '"' . $substrings [$i] . '"';
            $needComma = true;
        }
        if ($i < (count ( $substrings ) - 1)) {
            if ($needComma) {
                $sb .= ', ';
            }
            $sb .= "'\"'";
        }
    }
    $sb .= ')';
    return $sb;
}
function hhb_xml_encode(array $arr, string $name_for_numeric_keys = 'val'): string {
    if (empty ( $arr )) {
        // avoid having a special case for <root/> and <root></root> i guess
        return '';
    }
    $is_iterable_compat = function ($v): bool {
        // php 7.0 compat for php7.1+'s is_itrable
        return is_array ( $v ) || ($v instanceof \Traversable);
    };
    $isAssoc = function (array $arr): bool {
        // thanks to Mark Amery for this
        if (array () === $arr)
            return false;
        return array_keys ( $arr ) !== range ( 0, count ( $arr ) - 1 );
    };
    $endsWith = function (string $haystack, string $needle): bool {
        // thanks to MrHus
        $length = strlen ( $needle );
        if ($length == 0) {
            return true;
        }
        return (substr ( $haystack, - $length ) === $needle);
    };
    $formatXML = function (string $xml) use ($endsWith): string {
        // there seems to be a bug with formatOutput on DOMDocuments that have used importNode with $deep=true
        // on PHP 7.0.15...
        $domd = new DOMDocument ( '1.0', 'UTF-8' );
        $domd->preserveWhiteSpace = false;
        $domd->formatOutput = true;
        $domd->loadXML ( '<root>' . $xml . '</root>' );
        $ret = trim ( $domd->saveXML ( $domd->getElementsByTagName ( "root" )->item ( 0 ) ) );
        assert ( 0 === strpos ( $ret, '<root>' ) );
        assert ( $endsWith ( $ret, '</root>' ) );
        $full = trim ( substr ( $ret, strlen ( '<root>' ), - strlen ( '</root>' ) ) );
        $ret = '';
        // ... seems each line except the first line starts with 2 ugly spaces,
        // presumably its the <root> element that starts with no spaces at all.
        foreach ( explode ( "\n", $full ) as $line ) {
            if (substr ( $line, 0, 2 ) === '  ') {
                $ret .= substr ( $line, 2 ) . "\n";
            } else {
                $ret .= $line . "\n";
            }
        }
        $ret = trim ( $ret );
        return $ret;
    };

    // $arr = new RecursiveArrayIterator ( $arr );
    // $iterator = new RecursiveIteratorIterator ( $arr, RecursiveIteratorIterator::SELF_FIRST );
    $iterator = $arr;
    $domd = new DOMDocument ();
    $root = $domd->createElement ( 'root' );
    foreach ( $iterator as $key => $val ) {
        // var_dump ( $key, $val );
        $ele = $domd->createElement ( is_int ( $key ) ? $name_for_numeric_keys : $key );
        if (! empty ( $val ) || $val === '0') {
            if ($is_iterable_compat ( $val )) {
                $asoc = $isAssoc ( $val );
                $tmp = hhb_xml_encode ( $val, is_int ( $key ) ? $name_for_numeric_keys : $key );
                // var_dump ( $tmp );
                // die ();
                $tmp = @DOMDocument::loadXML ( '<root>' . $tmp . '</root>' );
                foreach ( $tmp->getElementsByTagName ( "root" )->item ( 0 )->childNodes ?? [ ] as $tmp2 ) {
                    $tmp3 = $domd->importNode ( $tmp2, true );
                    if ($asoc) {
                        $ele->appendChild ( $tmp3 );
                    } else {
                        $root->appendChild ( $tmp3 );
                    }
                }
                unset ( $tmp, $tmp2, $tmp3 );
                if (! $asoc) {
                    // echo 'REMOVING';die();
                    // $ele->parentNode->removeChild($ele);
                    continue;
                }
            } else {
                $ele->textContent = $val;
            }
        }
        $root->appendChild ( $ele );
    }
    $domd->preserveWhiteSpace = false;
    $domd->formatOutput = true;
    $ret = trim ( $domd->saveXML ( $root ) );
    assert ( 0 === strpos ( $ret, '<root>' ) );
    assert ( $endsWith ( $ret, '</root>' ) );
    $ret = trim ( substr ( $ret, strlen ( '<root>' ), - strlen ( '</root>' ) ) );
    // seems to be a bug with formatOutput on DOMDocuments that have used importNode with $deep=true..
    $ret = $formatXML ( $ret );
    return $ret;
}

ps, the lines require_once ('hhb_.inc.php');
$json_raw = (new hhb_curl ( '', true ))->exec ( 'https://servizionline.sanita.fvg.it/tempiAttesaService/tempiAttesaPs' )->getStdOut ();
are just fetching the url and putting the json in $json_raw (using gzip compressed transfer to speed things up btw), replace it with whatever you want to fetch it into $json_raw , the actual curl library i used is from https://github.com/divinity76/hhb_.inc.php/blob/master/hhb_.inc.php#L477

currently it prints:

string(18) "A.S.U.I. - Trieste"
string(41) "Pronto Soccorso e Terapia Urgenza Trieste"
string(9) "121200:14"
string(10) "181400:254"
string(6) "Bianco"
string(7) "200:292"
string(5) "00:00"
string(24) "Pronto Soccorso Maggiore"
string(7) "3300:15"
string(6) "Bianco"
string(8) "6200:584"
string(5) "00:00"
string(5) "00:00"
string(8) "4100:353"
string(6) "Bianco"
string(7) "100:051"
string(5) "00:00"
string(5) "00:00"
string(7) "1100:15"
string(8) "6402:012"
string(6) "Bianco"
string(7) "402:274"
string(5) "00:00"
string(9) "11900:202"
string(9) "11401:427"
string(6) "Bianco"
string(8) "2102:051"
string(5) "00:00"
string(7) "3300:08"
string(8) "7401:423"
string(6) "Bianco"
string(8) "8402:104"
string(5) "00:00"
string(6) "Bianco"
string(5) "00:00"
string(5) "00:00"
string(5) "00:00"
string(5) "00:00"
string(7) "1100:04"
string(10) "121000:512"
string(6) "Bianco"
string(8) "5400:461"
string(5) "00:00"
string(5) "00:00"
string(5) "00:00"
string(6) "Bianco"
string(5) "00:00"
string(5) "00:00"
string(9) "121200:18"
string(9) "11800:593"
string(6) "Bianco"
string(8) "6401:272"
string(5) "00:00"
string(6) "Bianco"
string(7) "1100:04"
string(5) "00:00"
string(5) "00:00"
string(5) "00:00"
string(7) "2200:05"
string(9) "10801:102"
string(6) "Bianco"
string(8) "8201:166"
string(5) "00:00"
string(8) "3200:071"
string(7) "100:261"
string(6) "Bianco"
string(5) "00:00"
string(5) "00:00"
string(7) "1100:00"
string(9) "151500:26"
string(10) "161301:123"
string(6) "Bianco"
string(8) "9500:434"
string(7) "1100:00"
string(7) "2200:13"
string(6) "Bianco"
string(7) "200:342"
string(5) "00:00"
string(6) "Bianco"
string(7) "1100:24"
string(5) "00:00"
string(5) "00:00"
string(5) "00:00"
string(7) "1100:04"
string(8) "9700:222"
string(10) "171500:582"
string(6) "Bianco"
string(7) "200:512"
string(7) "1100:40"
string(7) "1100:22"
string(6) "Bianco"
string(8) "3100:062"
string(5) "00:00"
string(5) "00:00"
string(5) "00:00"
string(6) "Bianco"
string(5) "00:00"
string(5) "00:00"
string(7) "1100:22"
string(8) "7500:302"
string(6) "Bianco"
string(5) "00:00"
string(5) "00:00"
string(7) "1100:06"
string(6) "Bianco"
string(7) "1100:00"
string(5) "00:00"
string(5) "00:00"

hope that’s what you were looking for, i was guessing by the “xpath” you provided.

Answer:

xpath is too complicated for your task and overkill in general…

just use the standard json_decode(), get the equivalent PHP object and navigate it using stardard for/while loops and regexes

Also I think your question is misleading, your problem is not parsing a JSON (that’s done by json_decode() automatically), your problem is extracting some data from it using xpath.. I suggest to have a refactor of your question showing exactly what goes wrong and what’s your intent

If you need to descent into a precise JSON node (or set of nodes), why you don’t do it by means of for loops and regexes?

Answer:

I would suggest trying to use a different library for JsonPath, if the one you are working with has a bug and the 3rd party service states no error in query.

Here are a few:

I am pretty sure there are more. Hope that helps.

Answer:

I’ve solved changing library implementation for JsonPath: now I use Skyscanner JsonPath implementation (ref. https://github.com/Skyscanner/JsonPath-PHP).

Some troubles on installation (for me, I never used composer before …), but the skyskanner team supported me (ref. https://github.com/Skyscanner/JsonPath-PHP/issues/6) and now I’ve this PHP code ….

<?php
    ini_set('display_errors', 'On');
    error_reporting(E_ALL);

    include "./tmp/vendor/autoload.php";

    $url = 'https://servizionline.sanita.fvg.it/tempiAttesaService/tempiAttesaPs';

    //#Set CURL parameters: pay attention to the PROXY config !!!!
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_AUTOREFERER, TRUE);
    curl_setopt($ch, CURLOPT_HEADER, 0);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_FOLLOWLOCATION, TRUE);
    curl_setopt($ch, CURLOPT_PROXY, '');
    $data = curl_exec($ch);
    curl_close($ch);

    $jsonObject = new JsonPath\JsonObject($data);

    $jsonPathExpr = "$..aziende[?(@.descrizione==\"A.S.U.I. - Trieste\")]..prontoSoccorsi[?(@.descrizione==\"Pronto Soccorso e Terapia Urgenza Trieste\")]..dipartimenti[?(@.descrizione==\"Pronto Soccorso Maggiore\")]..codiciColore[?(@.descrizione==\"Verde\")]..situazionePazienti..numeroPazientiInAttesa";

    $r = $jsonObject->get($jsonPathExpr);

    //print json_encode($r);

    print json_encode($r[0]);
?>

in ./tmp I’ve what I obtain from composer

enter image description here

… that works fine and in this way I can do my json query, potentially, without knowing its exact structure

Answer:

<?php // PRINT SI JSON ORIGINAL
define("DIRPATH", dirname($_SERVER["SCRIPT_FILENAME"]) . '/');
define("WEBPATH", 'http://' . $_SERVER['SERVER_ADDR'] . dirname($_SERVER['PHP_SELF']) . '/');
//define("WEBPORT", 'http://' . $_SERVER['SERVER_ADDR'] . ':' . $_SERVER['SERVER_PORT'] . dirname($_SERVER['PHP_SELF']) . '/');
//define("imgpath", DIRPATH . 'image/');
//$png = file_get_contents('iptv.kodi.al/images/');
$jsondata = file_get_contents('https://servizionline.sanita.fvg.it/tempiAttesaService/tempiAttesaPs');
header("Content-type: application/ld+json; charset=utf-8");
	$print = json_decode($jsondata);
	print_r($print);
?>

<?php // PRINT ME KATEGORI
define("DIRPATH", dirname($_SERVER["SCRIPT_FILENAME"]) . '/');
define("WEBPATH", 'http://' . $_SERVER['SERVER_ADDR'] . dirname($_SERVER['PHP_SELF']) . '/');
//define("WEBPORT", 'http://' . $_SERVER['SERVER_ADDR'] . ':' . $_SERVER['SERVER_PORT'] . dirname($_SERVER['PHP_SELF']) . '/');
//define("imgpath", DIRPATH . 'image/');
//$png = file_get_contents('iptv.kodi.al/images/');
$jsondata = file_get_contents('https://servizionline.sanita.fvg.it/tempiAttesaService/tempiAttesaPs');
header("Content-type: application/ld+json; charset=utf-8");
	$print = json_decode($jsondata);
	//print_r($print);
	$items = '';
	// KETU FILLON LISTA
	foreach ($print->{'aziende'} as $item) {
	$items .= '
' . $item->id . '
' . $item->descrizione . '
';
};
?>
<?php echo $items; ?>