Google plus like drag and drop adding groups

You might have marked a cool feature in google plus, where we add people to groups simply by dragging it to the perticular frame.

Here is a explanation of the above implementation using JQuery and PHP.

Sample database contains three tables and relationship between Members and Groups.

Members
Table contains members(users) data such as member_id, member_image and etc.

CREATE TABLE IF NOT EXISTS `members` (
`member_id` int(9) NOT NULL AUTO_INCREMENT,
`member_name` varchar(220) NOT NULL,
`member_image` text NOT NULL,
`dated` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
PRIMARY KEY (`member_id`)
);

Groups
Contains groups information.

CREATE TABLE IF NOT EXISTS `groups` (
`group_id` int(9)  AUTO_INCREMENT,
`group_name` varchar(220),
`sort` int(9),
`date` timestamp  DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
PRIMARY KEY (`group_id`),
KEY `sort` (`sort`)
);

User_group
Members and Groups table relationship table contains user_id(same as memeber_id), group_id, member_id() and sort(ordering)

CREATE TABLE IF NOT EXISTS `user_group` (
`id` int(9) NOT NULL AUTO_INCREMENT,
`user_id` int(9) NOT NULL,
`group_id` int(9) NOT NULL,
`member_id` int(9) NOT NULL,
`sort` int(9) NOT NULL,
PRIMARY KEY (`id`)
);

Javascript
Here draggable applying for two classes .members and .group

<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.6.2/jquery.js"></script>
<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jqueryui/1.8.14/jquery-ui.js"></script>
<script type="text/javascript" src="jquery.livequery.min.js"></script>
<script type="text/javascript" >
$(function()
{
// Initiate draggable for public and groups
var $gallery = $( ".members, .group" );
$( "img", $gallery ).live("mouseenter", function()
{
var $this = $(this);
if(!$this.is(':data(draggable)'))
{
$this.draggable({
helper: "clone",
containment: $( "#demo-frame" ).length ? "#demo-frame" : "document",
cursor: "move"
});
}
});
// Initiate Droppable for groups
// Adding members into groups
// Removing members from groups
// Shift members one group to another
$(".group").livequery(function(){
var casePublic = false;
$(this).droppable({
activeClass: "ui-state-highlight",
drop: function( event, ui ) {
var m_id = $(ui.draggable).attr('rel');
if(!m_id)
{
casePublic = true;
var m_id = $(ui.draggable).attr("id");
m_id = parseInt(m_id.substring(3));
}
var g_id = $(this).attr('id');
dropPublic(m_id, g_id, casePublic);
$("#mem"+m_id).hide();
$( "<li></li>" ).html( ui.draggable ).appendTo( this );
},
out: function(event, ui) {
var m_id = $(ui.draggable).attr('rel');
var g_id = $(this).attr('id');
$(ui.draggable).hide("explode", 1000);
removeMember(g_id,m_id);
}
});
});
// Add or shift members from groups
function dropPublic(m_id, g_id,caseFrom)
{
$.ajax({
type:"GET",
url:"groups.php?m_id="+m_id+"&g_id="+g_id,
cache:false,
success:function(response){
$.get("groups.php?reload_groups", function(data){
$("#groupsall").html(data);
$("#added"+g_id).animate({"opacity" : "10" },10);
$("#added"+g_id).show();
$("#added"+g_id).animate({"margin-top": "-50px"}, 450);
$("#added"+g_id).animate({"margin-top": "0px","opacity" : "0" }, 450);
});
}
});
}
// Remove memebers from groups
// It will restore into public groups or non grouped members
function removeMember(g_id,m_id)
{
$.ajax({
type:"GET",
url:"groups.php?do=drop&mid="+m_id,
cache:false,
success:function(response){
$("#removed"+g_id).animate({"opacity" : "10" },10);
$("#removed"+g_id).show();
$("#removed"+g_id).animate({"margin-top": "-50px"}, 450);
$("#removed"+g_id).animate({"margin-top": "0px","opacity" : "0" }, 450);
$.get("groups.php?reload", function(data){ $("#public").html(data); });
}
});
}
});
</script>

groups.php

<?php
require_once("multipleDiv.inc.php");
// Initiate Object
$obj = new Multiplediv();
// Add or Update Ajax Call
if(isset($_GET['m_id']) and isset($_GET['g_id']))
{
$obj->addMembers((int)$_GET['m_id'], (int)$_GET['g_id']);
exit;
}
// Remove Memebers from groups Ajax call
if(isset($_GET['do']))
{
$obj->removeMember($_GET['mid']);
exit;
}
// Reload groups each ajax call
if(isset($_GET['reload'])){ echo $obj->getMembers_reload(); exit; }
if(isset($_GET['reload_groups'])){ echo $obj->getmembergroups_reload(); exit; }
// Initiate Groups and members
$members = $obj->public_members();
$groups = $obj->groups();
?>
Friends
<div id="main_portion">
<div id="public">
<!-- Initiate members -->
<?php
if(!isset($members))
$members = $obj->public_members();
if($members)
{
foreach($members as $member)
{
extract($member);
echo "<div class='members' id='mem".$member_id."'>\n";
echo "<img src='images/".$member_image."' rel='".$member_id."'>\n";
echo "<b>".ucwords($member_name)."</b>\n";
echo "</div>";
}
}
else
echo "Members not available";
?>
</div>
<div id="groupsall">
Groups
<!-- Initiate Groups -->
<?php
if(!isset($groups))
$groups = $obj->groups();
if($groups)
{
foreach($groups as $group)
{
extract($group);
echo "<div id='".$group_id."' class='group'>\n";
echo ucwords($group_name);
echo "<div id='added".$group_id."' class='add' style='display:none;' ><img src='images/green.jpg'></div>";
echo "<div id='removed".$group_id."' class='remove' style='display:none;' ><img src='images/red.jpg'></div>";
echo "<ul>\n";
echo $obj->updateGroups($group_id);
echo "</ul></div>";
}
}
?>

multipleDiv.inc.php
Download this and modify database connection credentials.

<?php
// Database declaration's
define("SERVER", "localhost");
define("USER", "username");
define("PASSWORD", "password");
define("DB", "database");class Multiplediv
{
........................
........................
.........................
}
?>

Introduction to AJAX

AJAX, short for Asynchronous JavaScript And XML, allows you to load data in the background and display it on your webpage, without refreshing the page. This allows you to create websites with much richer functionality. Popular web applications like Gmail, Outlook Web Access, and Google Maps uses AJAX extensively, to provide you with a more responsive, desktop-like experience.

Using AJAX can be a bit cumbersome, because the various browsers have different implementations to support AJAX. Normally this would force you to write code to respond differently, depending on the browser, but fortunately, jQuery has done this for us, which allows us to write AJAX functionality with as little as a single line of code.

You should be aware of the fact that thre are both advantages and disadvantages to using AJAX on your page though, which means that you should always consider carefully before deciding to use it instead of doing a regular postback to the server. Here's a summary:

Advantages

• Your page will be more pleasant to use, when you can update parts of it without a refresh, which causes the browser to flicker and the statusbar to run.


• Because you only load the data you need to update the page, instead of refreshing the entire page, you save bandwidth.

Disadvantages

• Because the updates are done by JavaScript on the client, the state will not register in the browsers history, making it impossible to use the Back and Forward buttons to navigate between various states of the page.


• For the same reason, a specific state can't be bookmarked by the user.


• Data loaded through AJAX won't be indexed by any of the major search engines.


• People using browsers without JavaScript support, or with JavaScript disabled, will not be able to use the functionality that you provide through AJAX.

The first two items on the list may be circumvented though, typically through the use of an iframe and reading and writing data from the part of the URL after the # character.

In the following chapters, you will learn how to use various AJAX related functions of jQuery.