returning a PHP object from an ajax file to my javascript code

Question

So I'm still a newbie when it comes to javascript and php. I am having this issue:

from javascript, I scan a package's barcode using a barcode reader. I send this to an PHP file using ajax, Which builds an object, and needs to return it to my javascript code.

I'm doing this:

function LoadPackage(ScannedCode) {
 var res;
 console.time("Load package " + ScannedCode);
 $.ajax({
 type: "POST",
 url: "ajax/3gmodule_inventory_ajax/getPackage.php",
 data: "packageSerial=" + ScannedCode,
 cache: false,
 async: false //inline operation, cannot keep processing during the execution of the AJAX
 }).success(function(result) {
 res = $.parseJSON(result);
 });
 console.timeEnd("Load package " + ScannedCode);
 return res;
}

The php file:

 <?php
 include_once "../../init.php";
 $packageSerial = $_POST["packageSerial"];
 $package = tbProductPackage::getInstanceByPackageSerial($packageSerial, $db);
 return json_encode($package);
// edit: first part of the problem was here, I was supposed to ECHO here. not RETURN.
 ?> 

I am 100% certain my object gets built properly. I did do a var_dump of my $package object, and everything is fine with it. However, when trying to get it back to javascript, I tried a bunch of different things, nothing works.

The $.parseJSON(result); statement seems to be giving me this error:

Uncaught SyntaxError: Unexpected end of JSON input

I also tried to use serialize(), but I get an error message:

Uncaught exception 'PDOException' with message 'You cannot serialize or unserialize PDO instances'

Basically, My database is in my object, I'm guessing I can't serialize it...

What am I doing wrong here?

Thank you

• bassxzero: What is the data type of your $package object?
• Patrick Q: First, there is no such thing as an "ajax file". That's just a PHP file that you happen to be calling using ajax. Second, whatever your getInstanceByPackageSerial() function is returning either isn't what you think it is, or the way you're trying to do this isn't the right way. It would be helpful to know what your end objective is here. What do you end up trying to do with res in the javascript code? Third, you are using async: false in your ajax setup. This is generally not considered a good thing to do.
• Vítor Oliveira: Instead of use return, have you tried "die(json_encode($package));" ?
• TheValyreanGroup: In the .success function, why don't you log the result to see what the actual return object is. Whatever PHP is returning is not correctly formatted for JSON.
• Mathieu Turcotte: bass: the type is tbProductPackage. Is a custom class. Patrick: I'm sorry I used the wrong term. However, my getInstanceByPackageSerial() has been touroughly tested, and returns exactly what it should return: an instance of the tbProductPackage class. I am well aware I'm doing something the wrong way here, hence the question! ;)

Answer 1

In getPackage.php page :

echo json_encode($package);

not use return

In Jquery should be :

data: {packageSerial:ScannedCode},

After success not need $.parseJSON( because getPackage.php already retrieve json encode

so, is should be :

}).success(function(result) {
 res = result
});

also add dataType: 'json', after data: {packageSerial:ScannedCode},

So, Final correction code is :

Jquery :

function LoadPackage(ScannedCode) {
 var res;
 console.time("Load package " + ScannedCode);
 $.ajax({
 context: this,
 type: "POST",
 url: "ajax/3gmodule_inventory_ajax/getPackage.php",
 data: {packageSerial:ScannedCode},
 dataType: 'json',
 }).success(function(result) {
 res = result;
 });
 console.timeEnd("Load package " + ScannedCode);
 return res;
}

PHP :

<?php
 include_once "../../init.php";
 $packageSerial = $_POST["packageSerial"];
 $package = tbProductPackage::getInstanceByPackageSerial($packageSerial, $db);
 echo json_encode($package);
?>

• Mathieu Turcotte: mhhh. I'm going to try it but you are so right about the echo... I have no clue why I'm trying to do a return... again. I'm a n00b at php and javascript lol. I got my old .net thinking again lol. I'll try to put an echo instead and see if that helps. It should. The only thing though, like we discussed in the question intself... I am realizing I may not want to return the whole thing. I have the DB info in the object, and I'm worried I'll expose logins and stuff. I'll try it first and check the data that comes out of it, but I may have to construct something before "echoing" it in PHP...
• Mathieu Turcotte: well it kinda... didn't really... work... I did echo json_encode($package);, and I basically receive only { } in javascript... I just don'T get it... In PHP, I have the entire object... but it won'T go trough to javascript...
• Razib Al Mamun: try to run getPackage.php directly not help jquery just for test. and let me know can you get any data?
• Mathieu Turcotte: I'm on to something. I echoed: echo json_encode((array) $package); The cast to array seems to have helped. Now the problem is that the array of parts that is inside of my object gets out as { } { } { }... I'll have to find a way to convert those to arrays aswell... The good news thogh: my object does not include the login informations like I feared. Or rather... it tried, but it came out as { } as well haha
• Patrick Q: @MathieuTurcotte You may be interested in this answer to a similar question to the problem you seem to be encountering now.

Answer 2

Ajax expects the JSON inside the request body.

Use

die(json_encode($SOME_ARRAY_OR_OBJECT));

not "return" json_encode($SOME_ARRAY_OR_OBJECT)

Answer 3

I don't know how your database is done, but as a first step, you could make a SELECT query and fetch it as an array. Then, json_encode would work without problem. Something along the lines of:

$vec = array();
$query="SELECT * From YourTable
 WHERE 1";
$result= mysql_query($query) or die(mysql_error() . $query)
while ($r=mysql_fetch_array($result)) {
 $vec [] = $r;
}
$toreturn=json_encode($vec );

• WillardSolutions: Never use mysql_ extensions. Also, this answer really misses the point of the question and makes a lot of assumptions about OP's use-case.
• Mathieu Turcotte: I've done plenty of that in other circumstaces and I can get it to work. But I'm in a oop web application. I go through objects whenever I can. In some cases I do return stuff straight from a query, but that doesn't cut it here. Still, thanks for trying to help