json_encode boolean returning wrong value

Question

I'm writing a jquery login. If the php login script (checklogin.php) echoes "true" then my jquery page is supposed to give an alert. When I run a login.php (that doesn't use jquery) it sends the request to checklogin.php which echoes "true" however if I use my jquery login script to send the login info to checklogin.php, the alert I trace back says "false".

$('#login').click(function(e){
      $.getJSON("http://www.hedonsoft.com/game/login.php",{username: $("#username").val(), password: $("#password").val()},function(data){
         if(data==true){
            alert(data.boolean);
            //$('#logindiv').slideUp();
            //$('#gamediv').show(); 
            //$('#registerdiv').hide();
            //$('#gameheader').html(data['username']);
         }else{
            alert("false");
         }
      });
});

<?php
header('Access-Control-Allow-Origin: *');
$host="localhost"; // Host name 
$username=""; // Mysql username 
$password=""; // Mysql password 
$db_name="hedonsof_conflict"; // Database name 
$tbl_name="members"; // Table name 

// Connect to server and select databse.
mysql_connect("$host", "$username", "$password")or die("cannot connect"); 
mysql_select_db("$db_name")or die("cannot select DB");

// username and password sent from form 
$myusername=$_POST['myusername']; 
$mypassword=$_POST['mypassword']; 

// To protect MySQL injection (more detail about MySQL injection)
$myusername = stripslashes($myusername);
$mypassword = stripslashes($mypassword);
$myusername = mysql_real_escape_string($myusername);
$mypassword = mysql_real_escape_string($mypassword);

$sql="SELECT * FROM $tbl_name WHERE username='$myusername' and password='$mypassword'";
$result=mysql_query($sql);

// Mysql_num_row is counting table row
$count=mysql_num_rows($result);

// If result matched $myusername and $mypassword, table row must be 1 row
if($count==1){

// Register $myusername, $mypassword and redirect to file "login_success.php"
session_register("myusername");
session_register("mypassword"); 
$json = array('boolean' => 'true', 'jsonUser' => $myusername);
echo "true";
}
else {
echo "Wrong Username or Password";
}
?>

So long story short, when I try to login from a regular php page the value I trace is true, when I try to login from a jquery page the value I trace is false;

EDIT:

<?php
...
$sql="SELECT * FROM $tbl_name WHERE username='$myusername' and password='$mypassword'";
$result=mysql_query($sql);

// Mysql_num_row is counting table row
$count=mysql_num_rows($result);

// If result matched $myusername and $mypassword, table row must be 1 row
if($count==1){

// Register $myusername, $mypassword and redirect to file "login_success.php"
session_register("myusername");
session_register("mypassword"); 
$json = array('boolean' => true, 'jsonUser' => $myusername);
echo true;
}
else {
echo "Wrong Username or Password";
}
?>

And my jQuery...

$('#login').click(function(e){
      $.getJSON("http://www.hedonsoft.com/game/login.php",{username: $("#username").val(), password: $("#password").val()},function(data){
         if(data){
            alert("true");
            //$('#logindiv').slideUp();
            //$('#gamediv').show(); 
            //$('#registerdiv').hide();
            //$('#gameheader').html(data['username']);
         }else{
            alert(data); // shows null
         }
      });
});

With json_encode, boolean's value is returned null

$('#login').click(function(e){
       $.getJSON("http://www.hedonsoft.com/game/login.php",{username: $("#username").val(), password: $("#password").val()},function(data){
          if(data.boolean == "true"){
             alert("true");
             //$('#logindiv').slideUp();
             //$('#gamediv').show(); 
             //$('#registerdiv').hide();
             //$('#gameheader').html(data['username']);
          }else{            alert(data);
          }
       }); });

<?php
...
// Register $myusername, $mypassword and redirect to file "login_success.php"
session_register("myusername");
session_register("mypassword"); 
$json = array('boolean' => true, 'jsonUser' => $myusername);
echo json_encode($json);
}
...
?>

Solution

Use true, not 'true'. 'true' is a string, and you want a boolean:

$json = array('boolean' => true, 'jsonUser' => $myusername);

Also, never write == true.

if(data==true) {

---

Okay, now the problem is:

$json = array('boolean' => true, 'jsonUser' => $myusername);
echo true;

Don't echo true, echo json_encode($json).

Comments

[Mahn]

Is json_encode actually used somewhere, or are just collecting that echo "true"; as the ajax response?

[RapsFan1981]

Please see my edit. This is what I was originally trying but it kept returning null no matter what I did so I figured trying a simple string or boolean check would be easier, and once I got that working then I'd try this again.

[Ry-]

@RapsFan1981: See updated answer.

[Mahn]

"never write == true" -> why?

[Ry-]

@Mahn: It only leads to code errors. if(data == true) is usually equivalent to if(data). If it is equivalent, the == true is superfluous and should be taken out. If it's not equivalent, you have a serious problem with your code - as is the case here. At most use === true if you really need to check for a true value and nothing else.

[Mahn]

Hm, it may be just me, but I'm having a hard time imagining in what cases could if(data == true) not be equivalent to if(data), could you give an example? just curious.

[RapsFan1981]

No effect. alert("false"); is still firing.

[Ry-]

@Mahn: Well, JavaScript. 'true' != true but 'true' is truthy.

[Ry-]

@RapsFan1981: You're doing the == "true" thing again. Take it out.

[RapsFan1981]

$json = array('boolean' => true, 'jsonUser' => $myusername); if(data.boolean == true) but doesn't work

[Ry-]

@RapsFan1981: Don't do == true either. Take it out. Now, which browser are you using?

[Ry-]

let us continue this discussion in chat

[Mahn]

Did you manage to get it working? I believe you need either if(data) or if(data.boolean), and additionally perhaps setting an application/json header on the php side.

[RapsFan1981]

Stil not working, minitech has been helping me. I've tried if(data) and if(data.boolean).

[RapsFan1981]

after a lot of experimentation and changing things I got it going. I made a working registration script that uses .post so I ended up using .post for my login as well. I also added e.preventDefault() as suggested by minitech.