JQuery AJAX retrieving an Array of Objects

Question

I am trying to use json_encode so that my jquery ajax function can retrieve data from my php script however the array I am attempting to encode and retrieve is an array of objects

$la_uselessinfo = array();
$lv_cnt = 0;

$uselessinfo = pg_execute($gv_dbconn, "uselessinfo_cur", array());
while($la_row = pg_fetch_row($uselessinfo)) {

    $la_uselessinfo[$lv_cnt]["uinf_idno"] = $la_row[0];
    $la_uselessinfo[$lv_cnt]["uinf_desc"] = $la_row[1];
    $lv_cnt = $lv_cnt + 1;

}

echo json_encode($la_uselessinfo);

I am trying to retrieve this using the jquery ajax function

$.ajax({
    url     : 'scripts/phpfunctions.php',
    type    : 'GET',
    data    : {'action':'sel_uselessinfo'},
    success : function(data) {
                  //console.log(data);
                  console.log(data["uinf_desc"][0]);
              },
    error   : function(log) {
                  console.log(log.message);
              }
});

I am getting the following error

Uncaught TypeError: Cannot read property '0' of undefined

I can't tell if it's going wrong in the php code or the jquery code, what is the correct way to retrieve an array of objects?

You have one more parameter to parse. you are sending it as [$lv_cnt]["uinf_idno"] right? — Guruprasad J Rao
– Guruprasad J Rao, Commented Nov 19, 2015 at 13:18
Where you do json_encode(array($la_uselessinfo)); are you sure you dont really want json_encode($la_uselessinfo);? $la_uselessinfo is already an array, no need to wrap it again, and doing so causes you to misjudge the depth of your array — Wesley Smith
– Wesley Smith, Commented Nov 19, 2015 at 13:24

Wesley Smith · Accepted Answer · 2015-11-19 13:47:22Z

1

Change your PHP to:

$la_uselessinfo = array();
$lv_cnt = 0;

$uselessinfo = pg_execute($gv_dbconn, "uselessinfo_cur", array());
while($la_row = pg_fetch_row($uselessinfo)) {

    $la_uselessinfo[$lv_cnt]["uinf_idno"] = $la_row[0];
    $la_uselessinfo[$lv_cnt]["uinf_desc"] = $la_row[1];
    $lv_cnt = $lv_cnt + 1;

}

echo json_encode($la_uselessinfo); //$la_uselessinfo is already an array, no need to wrap it again, and doing so causes you to misjudge the depth of your array

Then change your jQuery to :

$.ajax({
    url     : 'scripts/phpfunctions.php',
    type    : 'GET',
    data    : {'action':'sel_uselessinfo'},
    success : function(data) {
                  //console.log(data);
                  console.log(data[0]["uinf_desc"]); // this line changed
              },
    error   : function(log) {
                  console.log(log.message);
              }
});

To loop over your results do this:

 // sample data
var data = [{
  "uinf_idno": "1",
  "uinf_desc": "website db "
}, {
  "uinf_idno": "2",
  "uinf_desc": "local apache "
}]



$.each(data,function(i,e){
       var uinf_idno = e.uinf_idno;
       var uinf_desc = e.uinf_desc;
       
      $('#result').append('uinf_idno= '+uinf_idno+' and uinf_desc= '+uinf_desc+' <br>');
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

<div id="result"></div>

answered Nov 19, 2015 at 13:47

Wesley Smith

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1 Comment

TheLovelySausage Over a year ago

this is perfect and very indepth

void · Accepted Answer · 2015-11-19 13:17:23Z

1

$.ajax({
    url     : 'scripts/phpfunctions.php',
    type    : 'GET',
    data    : {'action':'sel_uselessinfo'},
    dataType: "json",
    success : function(data) {
                  console.log(data[0]["uinf_desc"]);
                  console.log(data[0]["uinf_desc"]);
              },

It should be data[0]["uinf_desc"] as written in your PHP

answered Nov 19, 2015 at 13:17

void

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3 Comments

Wesley Smith Over a year ago

I wasnt the downvoter, but maybe because this will work now with the OP's edit,but before they edited though, this would have needed to be data[0][0]["uinf_desc"]

void Over a year ago

It will be just data[0]["uinf_desc"]

Wesley Smith Over a year ago

Now yes, but orriginally the OP's code was calling json_encode(array($la_uselessinfo)); wich was wrapping the array in another arry before turning it into JSON meaning it would need to be accessed via data[0][0]["uinf_desc"]

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