CONTOH LOGIN USER

(A) Controller
function submit_user(){
		$username = db_clean($this->input->post('name'));
		$success = $this->auth->do_login($username);
		if ($success)
		{
			$referrer_url = $this->session->userdata('referrer_url');
			if ($referrer_url == '')
				$redirect_back = site_url('dashboard/index');
			else
			{
				$redirect_back = site_url($referrer_url);
				$this->session->unset_userdata('referrer_url');
			}
			$data = array('status' => 'sukses', 'redirect_back' => $redirect_back);
		}
		else
		{
			$data = array('status' => 'gagal');
		}


		echo json_encode($data);
	}

(B) Library/Model
function do_login($username)
	{
		// cek di database, ada ga?
		$CI =& get_instance();

		$CI->db->select('tb_user.*, tb_level.*');
		$CI->db->from('tb_user');
		$CI->db->join('tb_level','tb_user.user_level = tb_level.id_level','left');
		$CI->db->where('tb_user.user_username',$username);

		$result = $CI->db->get();
		if($result->num_rows() == 0)
		{
			// username dan password tsb tidak ada
			return false;
		}
		else
		{
			// ada, maka ambil informasi dari database
				$userdata = $result->row();
				$session_data = array(
					'level'			=> $userdata->user_level,
					'username'		=> $userdata->user_username,
					'namauser'		=> $userdata->user_nama,

				);
				// buat session
				$CI->session->set_userdata($session_data);

				return true;
		}
	}

(C) View
<?php
	//header("Cache-Control: no-store, no-cache, must-revalidate, max-age=0");
	//header("Cache-Control: post-check=0, pre-check=0", false);
	//header("Pragma: no-cache");

	if ( ! defined('BASEPATH')) exit('No direct script access allowed'); ?>
    <div id="view">
    	<form id="demo-form">
        	<h1>Login Form</h1>
        	<div>
        		<input type="text" text-align="center" class="form-control" placeholder="No Mobile - ENTER" required id="username" />
        		<div id="pesan-error" class="alert alert-danger"></div>
        	</div>
        </form>
    </div>

<script>
$(document).ready(function() {
	$("#pesan-error").hide();

	$('#username').on('keydown', function(event) {
		if(event.which == 13) {

	    	var user_name = $("#username").val();
	    	if ($.trim(user_name).length < 1) {
	    		$('#pesan-error').show();
	    		$('#pesan-error').html('Harap input No Mobile');
	    	}
	    	else
	    	{
		  		$.ajax({
	  			type: "POST",
	  			url: "<?php echo site_url('web/submit_user'); ?>",
	  			dataType: 'json',
	  			data: {name: user_name},
	  			beforeSend: function(e) {
	  				if(e && e.overrideMimeType) {
	  			          e.overrideMimeType("application/json;charset=UTF-8");
	  			        }
	  			},
	  			success: function(data){
					 if (data.status == 'sukses')
					 {
						 alert('welcome to app_stock');
						 window.location.href = data.redirect_back;
					 }
					 else
					 {
						 alert('login gagal');
						 location.href = location.pathname;
					 }
				},
	  			error: function (xhr, ajaxOptions, thrownError)
	  			{ // Ketika terjadi error
	  			    alert(xhr.responseText); // munculkan alert
	  			}
	  		});
		  }

    	  return false;
	  }
	});

});
</script>