retrieve data from .post - php

Question

I'm using codeigniter, I had a problem to process a data using jQuery $.post function. I want to send a value such as subjectid to ajax_get_subject_credit function and retrieve another field within same database table. The result shows on another text field. Here is my code.
View:
$.post('<?php echo site_url('academic/ajax_get_subject_credit'); ?>', {'subjectid':subjectid}, function(data){
$('#chours' + id).val(data); });
This get a value from drop-down and I want to make a text field automatic populate from drop-down. #chours is a text field ID.
Controller:
function ajax_get_subject_credit($result)
{
$this->db->select('subjectid, subjectcredit');
$query = $this->db->get('ref_subject');
$result = $query->result_array();
$query->free_result();
$subjectid = array();
foreach($result as $row)
{
$result = $result + array($row['subjectid'] => $row['subjectcredit']);
}
return $result;
}
Modified In Controller
I also tried using this statement in controller for direct calling the field but still no success :
function ajax_get_subject_credit($subjectid)
{
$this->db->select('subjectid, subjectcredit');
$this->db->where('subjectid',$subjectid);
$query = $this->db->get('ref_subject');
$credithour = $query->row()->subjectcredit;
$query->free_result();
echo $credithour;
}

Answer 1

I am going to provide a general example here
in view file
$.post('<?php echo site_url("test/test"); ?>', {'id':1}, function(response){
if(response.success)
{
alert(response.message);
} else
{
alert('Something went wrong!!');
}
}, 'json');
in controller Test.php
function test()
{
$id = $this->input->post('id');
//do additional stuff
$result = 'i am coming right out of controller!! ';
echo json_encode(array('success' => true, 'message' => $result));
}

Answer 2

Dont use return to return value to AJAX. use echo
change this,
return $result;
to
echo $result;

Answer 3

If you want your method to return an array that the javascript can use to populate a dropdown, you probably don't want to return a string.
Try something like this:
function ajax_get_subject_credit()
{
$query = $this->db->select('subjectid, subjectcredit')->get('ref_subject');
$result = $query->result();
$out = array();
foreach($result as $row) {
$out[$row->subjectid] = $row->subject_credit;
}
header('Content-Type: application/json');
echo json_encode($out);
}
This will return a JSON array to your view, which your javascript method can use to populate the dropdown with values and labels.

Answer 4

Here is my Result:
In View :
function subjectid_change(id, subjectid){
//Set value
setValue(id, subjectid);
$.post('<?php echo site_url('academic/ajax_get_subject_credit'); ?>', {'subjectid':subjectid}, function(response){
if(response.success)
{
$('#chours' + id).val(response.value);
} else
{
alert('Something went wrong!!');
}
}, 'json'); }
And my controller :
function ajax_get_subject_credit()
{
//Get Post Value
$subjectid = $this->input->post('subjectid');
//Select subjectid,subjectcredit FROM
$this->db->select('subjectid, subjectcredit');
//Where subjectid = 'subjectid'
$this->db->where('subjectid',$subjectid);
//Database name
$query = $this->db->get('ref_subject');
$credithour = $query->row()->subjectcredit;
$query->free_result();
$result = $credithour;
echo json_encode(array('success' => true, 'value' => $result));
}
Thanks to everybody who helped me.