Question

I am attempting to make an AJAX call to a very small PHP script that should return me an array that could be echo’d and decoded using JQuery. Here is what I have:

My PHP page called to by AJAX:

$web_q=mysql_query("select * from sec_u_g where uid='$id' ");
$rs = array();
while($rs[] = mysql_fetch_assoc($web_q)) {
}
print_r(json_encode($rs));

This outputs:

[{"id":"3","uid":"39","gid":"16"},{"id":"4","uid":"39","gid":"4"},{"id":"5","uid":"39","gid":"5"},{"id":"6","uid":"39","gid":"6"},{"id":"7","uid":"39","gid":"7"},{"id":"8","uid":"39","gid":"8"},{"id":"9","uid":"39","gid":"9"},false] 

I don’t understand the “false” at the end for one .. But then I send to to JQuery and use:

$.each(json.result, function(i, object) {
$.each(object, function(property, value) {
    alert(property + "=" + value);
});
});

This just fails. I try to alert “result” by itself which is set by:

  $.post("get_ug.php",{id:txt},function(result){
  });

My output alerts are as follows:

1)  The key is '0' and the value is '['
2)  The key is '1' and the value is 'f'
3)  The key is '2' and the value is 'a'
4)  The key is '3' and the value is 'l'
5)  The key is '4' and the value is 's'
6)  The key is '5' and the value is 'e'
7)  The key is '6' and the value is ']'
8)  The key is '7' and the value is '
    '    (<-- Yes the line break is there in the alert)

I am exhausted from trying different ideas and scripts. Other than setting a delimiter myself and concatenating my own array and decoding it with a custom script, does anyone have any ideas?? Thank you!!

Answer 1

the false comes from your while loop:

while($rs[] = mysql_fetch_assoc($web_q))

at the last iteration, mysql_fetch_assoc returns false, which is inserted to $rs[], and thus finds it way to your json.
This is also what causes your json to be invalid.
get rid of this false by using a temporary variable for the loop.
everything should be fine afterwards.

Edit (Revised code with temporary variable):

$web_q=mysql_query("select * from sec_u_g where uid='$id' ");
$rs = array();
$result; //temporary variable to hold the current 'fetch' result.
while($result = mysql_fetch_assoc($web_q)) {
    array_push($rs, $result); //push the result into the array only if it
                              //passed the loop condition.
}
print_r(json_encode($rs));

note:
instead of array_push($rs, $result); you could of course also use $rs[] = $result;.

Edit 2 (jQuery + json):
in order to parse the json object, here’s an example of how to build the ajax call:

$.ajax({
    url: "get_ug.php",
    data: {
        id: txt
    },
    type: "POST",
    dataType: "json", //important (!!) - this makes sure the received data is parsed as json.
    success: function(data){
        //'data' is the resulting json object which is received from your php file.
        //use it to access your data.
        console.log( data );
    }
});