basic usage of AJAX with php for Database update and retrieval

Question

(Just a heads up, its a Lengthy question but im sure its very basic question for a ajax-php coder) Im trying to 'update db on some drag n drop event on one page' and 'reflect that change in other page without reload'. I have already written pretty much all the code, need your help in figuring out what is wrong. Here is the Html that I have written,

First_html_file:

<head>
    <title>Coconuts into Gunnybags</title>
    <link rel="stylesheet" href="style.css" type="text/css" media="screen" />
    <script type="text/javascript" src="script.js"></script>
</head>

<body>
    <div id="coconuts" style="float:left">
        <div class="coconut1" ondragover="allowDrop(event)" ondrop="drop(event)">
            <img id="drag1" ondragstart="drag(event)" draggable="true" src="coconut.png">
        </div>
        <div class="coconut2" ondragover="allowDrop(event)" ondrop="drop(event)">
            <img id="drag2" ondragstart="drag(event)" draggable="true" src="coconut.png">
        </div>

    </div>

    <div class="gunnybag" style="float:right">
        <div id="place1" ondragover="allowDrop(event)" ondrop="drop(event)"></div>
        <div id="place2" ondragover="allowDrop(event)" ondrop="drop(event)"></div>

    </div>
</body>

so there are 2 drag-able coconuts and there are 2 placeholders(place1 & place2). What I want to do is when the coconuts are dragged and placed on one of the placeholders, database's values should be updated. (say when a coconut is placed in 1st placeholder, place_id 1 - true, place_id 2 - false)

For this, I'm making ajax call to a php file from JS's drop function like this..

JS_file:

function drop(ev)
{
ev.preventDefault();
var data=ev.dataTransfer.getData("coconut");
ev.target.appendChild(document.getElementById(data));
    var state = true;           
    var id = ev.target.id;
$.ajax({
     url: "db_update.php",        //calling db update file.
     type: "POST",
     data: { id: id, state: state },       //2 variables place_id and its     state(True/False)
     cache: false,
     success: function (response) {    //I dont know what to do on success. Can this be left blank like, success:         ?
         $('#text').html(response);
     }
 });
}

This is my db_update, db_update:

    <?php

    $state = $_POST['state'];       //getting my variables state 'n ID
    $id = $_POST['id'];

    function begin()
    {
    mysql_query("BEGIN");
    }

    function commit()
    {
    mysql_query("COMMIT");
    }

    $con=mysql_connect("sqlservername","myuname", "mypass") or die(mysql_error());

    mysql_select_db("my_db", $con) or die(mysql_error());

    $query = "UPDATE gunnybag SET state = '{$state}' where id='{$id}'";  //will this work? or am I doing something wrong here??

    begin();

    $result = mysql_query($query);

    if($result)
    {
    commit(); 
    echo "successful";
    }

    ?>

On the receiving side I want to update the coconuts in the gunnybag without reloading the page, so I have written this ajax which uses db_fetch.php

ajx.js file:

window.onLoad = doAjax;

function doAjax(){
$.ajax({
url: "db_fetch.php",
dataType: "json",
success: function(json){
    var dataArray = JSON.decode(json);
    dataArray.each(function(entry){
        var i=1;
        if(entry.valueName==true){
            $q('place'+i).css( "display","block" );
        }
        else{
            $q('place'+i).css( "display","none" );
        }
        i=i++;
    })
}

}).complete(function(){
      setTimeout(function(){doAjax();}, 10000);
    });
}

here is the db_fetch.php:

<?php
try{
  $con=mysql_connect("sqlservername","myuname", "mypass") or die(mysql_error());
}
catch(Exception $e){
    echo $e;
}
mysql_select_db("my_db", $con) or die(mysql_error());

$q = mysql_query("SELECT 'state' FROM 'gunnybag' ");  //fetching all STATE from db
$query = mysql_query($q, $con);
$results = mysql_fetch_assoc($query);
echo json_encode($results);              //making it JSON obj

?>

Finally my other page where this ajax is being called from. Second_html_file:

    <head>
    <title>Coconuts into Gunnybags</title>
    <link rel="stylesheet" href="style.css" type="text/css" media="screen" />
    <script type="text/javascript" src="ajx.js"></script>  
               //if i simply include the ajax script here will it be called 
             //automatically? i want this script to keep up with the changes in db.
</head>

<body>
    <div class="gunnybag" style="float:right">
        <div id="place1" style="display: ;"><img id="drag1"  draggable="true" src="coconut.png"></div>
        <div id="place2" style="display: ;"><img id="drag2"  draggable="true" src="coconut.png"></div>

    </div>
</body>

MAP: First_html_file->JS_file->db_update :: Second_html_file->ajx.js->db_fetch.

Please point out what is wrong in this code, also respond to the //comments which are put along code. Your response is much appreciated. Thanks! #help me get this right# For ref I have hosted the files here, http://www.nagendra.0fees.net/admin.html & http://www.nagendra.0fees.net/cng.html

Answer 1

First thing I see is:

You say:

var id = event.target.id;

but you decalare ev in drop(ev)

so change that:

var id = event.target.id;

to:

var id = ev.target.id;

for starters.

Then you should use mysqli since mysql is deprecated:

Your code is also open for SQL-injections, so change:

$state = $_POST['state'];       //getting my variables state 'n ID
$id = $_POST['id'];

to:

$state = ($_POST['state']) ? true : false;       
$id = intval($_POST['id']); //make sure an integer

basic usage of AJAX with php for Database update and retrieval

Question

1 answers

solution1
1 2013-04-12 08:32:17

basic usage of AJAX with php for Database update and retrieval

Question

1 answers

solution1 1 2013-04-12 08:32:17

solution1
1 2013-04-12 08:32:17