Using jQuery JSON in CodeIgniter - php

Question

In CI, I have setup a controller with a method of logsig(). Then in my index() method I'm calling a view called startpage. In my view I'm using JSON to make an asynchronous call between my view and my controller. How would I code the call. Below is the code I have:
Contoller:
function logsig() {
$this->load->view('startpage', $sync);
header('Content-type:application/json'); .............
View:
<script type="text/javascript" language="javascript">
$(document).ready(function() {
// blink script
$('#notice').blink();
$("#action_button").click(function() {
var username = $("#username").val();
var password = $("#password").val();
var dataString = '&username=' + username + '&password=' + password;
if(username=='' || password=='') {
$('#success').fadeOut(400).hide();
$('#error').fadeOut(400).show();
} else {
$.ajax({
type: "POST",
dataType: "JSON",
url: "processing/logsig.php",
data: dataString,
json: {session_state: true},
success: function(data){
if(data.session_state == true) { // true means user is logged in.
$("#main1").hide();
$('#main1').load('<?=$sync?>').fadeIn();
} else if(data.session_state == false) { // false means user is being registered.
$("#action_button").remove();
$('#success').load('<?=$sync?>');
// onLoad fadeIn
}
}
});
}
});
});
</script>

Answer 1

You can't have your controller load a view and return JSON at the same time. Break out the JSON portion to a separate function.
An oversimplified example could look like this:
// Your existing function, but only displaying the view
function logsig() {
$this->load->view('startpage', $sync);
}
// A new function whose sole purpose is to return JSON
// Also notice we're using CI's Output class, a handy way to return JSON.
// More info here: codeigniter.com/user_guide/libraries/output.html
function get_json() {
$this->output->set_content_type('application/json')
->set_output(json_encode(array('foo' => 'bar')));
}
Then, in your JavaScript, call get_json:
$.ajax({
type: "POST",
dataType: "JSON",
url: "<?php echo site_url('processing/get_json.php'); ?>",
// ... truncated for brevity ...
});

Answer 2

If I read your question correctly, your JS postback code isn't working:
url: "processing/logsig.php",
Your CI url should be something like:
url: <?php echo site_url("processing/logsig"); ?>,
The site_url() function requires the URL helper. Load that in the beginning of your loadsig() function:
$this->load->helper('url');

Answer 3

Try This
Controller ---------
public function AjaxTest() {
$rollNumber = $this->input->post('rollNumber');
$query = $this->welcome_model->get_students_informationByRoll($rollNumber);
$array = array($query);
header('Content-Type: application/json', true);
echo json_encode($array);
}
View-----
<?php echo validation_errors(); ?>
<?php echo form_open('welcome/SearchStudents'); ?>
<input type="text" id="txtSearchRoll" name="roll" value="" />
<input type="submit" name="btnSubmit" value="Search Students" onclick="return CheckAjaxCall();"/>
<?php echo '</form>'; ?>
Scripts ----------
function CheckAjaxCall()
{
$.ajax({
type:'POST',
url:'<?php echo base_url(); ?>welcome/AjaxTest',
dataType:'json',
data:{rollNumber: $('#txtSearchRoll').val()},
cache:false,
success:function(aData){
//var a = aData[0];
//alert(a[0].roll);
$.map(aData, function (item) {
var stData = "<td>"+ item[0].roll +"</td>" +
" <td>"+item[0].Name+"</td>" +
"<td>"+item[0].Phone+"</td>" +
"<td> Edit </td>"+
"<td> Delete </td>";
$('#tblStudent').text("");
$('#tblStudent').append(stData);
//alert (item[0].roll + " " + item[0].Name);
});
//alert(aData);
},
error:function(){alert("Connection Is Not Available");}
});
return false;
}