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CodeIgniter is an Application Development Framework - a toolkit - for people who build web sites using PHP. Its goal is to enable you to develop projects much faster than you could if you were writing code from scratch, by providing a rich set of libraries for commonly needed tasks, as well as a simple interface and logical structure to access these libraries. CodeIgniter lets you creatively focus on your project by minimizing the amount of code needed for a given task.

Showing posts with label ajax. Show all posts

Monday, 11 July 2011

AJAX :: POLL Example

AJAX Poll

The following example will demonstrate a poll where the result is shown without reloading.

Do you like PHP and AJAX so far?

Example Explained - The HTML Page

When a user choose an option above, a function called "getVote()" is executed. The function is triggered by the "onclick" event:

<html>
<head>
<script type="text/javascript">
function getVote(int)
{
if (window.XMLHttpRequest)
{// code for IE7+, Firefox, Chrome, Opera, Safari
xmlhttp=new XMLHttpRequest();
}
else
{// code for IE6, IE5
xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
}
xmlhttp.onreadystatechange=function()
{
if (xmlhttp.readyState==4 && xmlhttp.status==200)
    {
  document.getElementById("poll").innerHTML=xmlhttp.responseText;
    }
}
xmlhttp.open("GET","poll_vote.php?vote="+int,true);
xmlhttp.send();
}
</script>
</head>
<body>

<div id="poll">
<h3>Do you like PHP and AJAX so far?</h3>
<form>
Yes:
<input type="radio" name="vote" value="0" onclick="getVote(this.value)" />
<br />No:
<input type="radio" name="vote" value="1" onclick="getVote(this.value)" />
</form>
</div>

</body>
</html>

The getVote() function does the following:

Create an XMLHttpRequest object
Create the function to be executed when the server response is ready
Send the request off to a file on the server
Notice that a parameter (vote) is added to the URL (with the value of the yes or no option)

The PHP File

The page on the server called by the JavaScript above is a PHP file called "poll_vote.php":

<?php
$vote = $_REQUEST['vote'];

//get content of textfile
$filename = "poll_result.txt";
$content = file($filename);

//put content in array
$array = explode("||", $content[0]);
$yes = $array[0];
$no = $array[1];

if ($vote == 0)
  {
  $yes = $yes + 1;
  }
if ($vote == 1)
  {
  $no = $no + 1;
  }

//insert votes to txt file
$insertvote = $yes."||".$no;
$fp = fopen($filename,"w");
fputs($fp,$insertvote);
fclose($fp);
?>

<h2>Result:</h2>
<table>
<tr>
<td>Yes:</td>
<td>
<img src="poll.gif"
width='<?php echo(100*round($yes/($no+$yes),2)); ?>'
height='20'>
<?php echo(100*round($yes/($no+$yes),2)); ?>%
</td>
</tr>
<tr>
<td>No:</td>
<td>
<img src="poll.gif"
width='<?php echo(100*round($no/($no+$yes),2)); ?>'
height='20'>
<?php echo(100*round($no/($no+$yes),2)); ?>%
</td>
</tr>
</table>

The value is sent from the JavaScript, and the following happens:

Get the content of the "poll_result.txt" file
Put the content of the file in variables and add one to the selected variable
Write the result to the "poll_result.txt" file
Output a graphical representation of the poll result

The Text File

The text file (poll_result.txt) is where we store the data from the poll.
It is stored like this:

0||0

The first number represents the "Yes" votes, the second number represents the "No" votes.
Note: Remember to allow your web server to edit the text file. Do NOT give everyone access, just the web server (PHP).

AJAX :: RSS Reader

An RSS Reader is used to read RSS Feeds.

AJAX RSS Reader

The following example will demonstrate an RSS reader, where the RSS-feed is loaded into a webpage without reloading:

Example Explained - The HTML Page

When a user selects an RSS-feed in the dropdown list above, a function called "showResult()" is executed. The function is triggered by the "onchange" event:

<html>
<head>
<script type="text/javascript">
function showRSS(str)
{
if (str.length==0)
{
  document.getElementById("rssOutput").innerHTML="";
return;
}
if (window.XMLHttpRequest)
{// code for IE7+, Firefox, Chrome, Opera, Safari
xmlhttp=new XMLHttpRequest();
}
else
{// code for IE6, IE5
xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
}
xmlhttp.onreadystatechange=function()
{
if (xmlhttp.readyState==4 && xmlhttp.status==200)
    {
    document.getElementById("rssOutput").innerHTML=xmlhttp.responseText;
    }
}
xmlhttp.open("GET","getrss.php?q="+str,true);
xmlhttp.send();
}
</script>
</head>
<body>

<form>
<select onchange="showRSS(this.value)">
<option value="">Select an RSS-feed:</option>
<option value="Google">Google News</option>
<option value="MSNBC">MSNBC News</option>
</select>
</form>
<br />
<div id="rssOutput">RSS-feed will be listed here...</div>
</body>
</html>

The showResult() function does the following:

Check if an RSS-feed is selected
Create an XMLHttpRequest object
Create the function to be executed when the server response is ready
Send the request off to a file on the server
Notice that a parameter (q) is added to the URL (with the content of the dropdown list)

The PHP File

The page on the server called by the JavaScript above is a PHP file called "getrss.php":

<?php
//get the q parameter from URL
$q=$_GET["q"];

//find out which feed was selected
if($q=="Google")
  {
  $xml=("http://news.google.com/news?ned=us&topic=h&output=rss");
  }
elseif($q=="MSNBC")
  {
  $xml=("http://rss.msnbc.msn.com/id/3032091/device/rss/rss.xml");
  }

$xmlDoc = new DOMDocument();
$xmlDoc->load($xml);

//get elements from "<channel>"
$channel=$xmlDoc->getElementsByTagName('channel')->item(0);
$channel_title = $channel->getElementsByTagName('title')
->item(0)->childNodes->item(0)->nodeValue;
$channel_link = $channel->getElementsByTagName('link')
->item(0)->childNodes->item(0)->nodeValue;
$channel_desc = $channel->getElementsByTagName('description')
->item(0)->childNodes->item(0)->nodeValue;

//output elements from "<channel>"
echo("<p><a href='" . $channel_link
  . "'>" . $channel_title . "</a>");
echo("<br />");
echo($channel_desc . "</p>");

//get and output "<item>" elements
$x=$xmlDoc->getElementsByTagName('item');
for ($i=0; $i<=2; $i++)
  {
  $item_title=$x->item($i)->getElementsByTagName('title')
  ->item(0)->childNodes->item(0)->nodeValue;
  $item_link=$x->item($i)->getElementsByTagName('link')
  ->item(0)->childNodes->item(0)->nodeValue;
  $item_desc=$x->item($i)->getElementsByTagName('description')
  ->item(0)->childNodes->item(0)->nodeValue;

  echo ("<p><a href='" . $item_link
  . "'>" . $item_title . "</a>");
  echo ("<br />");
  echo ($item_desc . "</p>");
  }
?>

When an RSS-feed is sent from the JavaScript, the following happens:

Check which feed was selected
Create a new XML DOM object
Load the RSS document in the xml variable
Extract and output elements from the channel element
Extract and output elements from the item element

AJAX :: XML and AJAX

AJAX can be used for interactive communication with an XML file.

AJAX XML Example

The following example will demonstrate how a web page can fetch information from an XML file with AJAX:

Example Explained - The HTML Page

When a user selects a CD in the dropdown list above, a function called "showCD()" is executed. The function is triggered by the "onchange" event:

<html>
<head>
<script type="text/javascript">
function showCD(str)
{
if (str=="")
{
document.getElementById("txtHint").innerHTML="";
return;
}
if (window.XMLHttpRequest)
{// code for IE7+, Firefox, Chrome, Opera, Safari
xmlhttp=new XMLHttpRequest();
}
else
{// code for IE6, IE5
xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
}
xmlhttp.onreadystatechange=function()
{
if (xmlhttp.readyState==4 && xmlhttp.status==200)
    {
    document.getElementById("txtHint").innerHTML=xmlhttp.responseText;
    }
}
xmlhttp.open("GET","getcd.php?q="+str,true);
xmlhttp.send();
}
</script>
</head>
<body>

<form>
Select a CD:
<select name="cds" onchange="showCD(this.value)">
<option value="">Select a CD:</option>
<option value="Bob Dylan">Bob Dylan</option>
<option value="Bonnie Tyler">Bonnie Tyler</option>
<option value="Dolly Parton">Dolly Parton</option>
</select>
</form>
<div id="txtHint"><b>CD info will be listed here...</b></div>

</body>
</html>

The showCD() function does the following:

Check if a CD is selected
Create an XMLHttpRequest object
Create the function to be executed when the server response is ready
Send the request off to a file on the server
Notice that a parameter (q) is added to the URL (with the content of the dropdown list)

The PHP File

The page on the server called by the JavaScript above is a PHP file called "getcd.php".
The PHP script loads an XML document, "cd_catalog.xml", runs a query against the XML file, and returns the result as HTML:

<?php
$q=$_GET["q"];

$xmlDoc = new DOMDocument();
$xmlDoc->load("cd_catalog.xml");

$x=$xmlDoc->getElementsByTagName('ARTIST');

for ($i=0; $i<=$x->length-1; $i++)
{
//Process only element nodes
if ($x->item($i)->nodeType==1)
  {
  if ($x->item($i)->childNodes->item(0)->nodeValue == $q)
    {
    $y=($x->item($i)->parentNode);
    }
  }
}

$cd=($y->childNodes);

for ($i=0;$i<$cd->length;$i++)
{
//Process only element nodes
if ($cd->item($i)->nodeType==1)
  {
echo("<b>" . $cd->item($i)->nodeName . ":</b> ");
  echo($cd->item($i)->childNodes->item(0)->nodeValue);
  echo("<br />");
  }
}
?>

When the CD query is sent from the JavaScript to the PHP page, the following happens:

PHP creates an XML DOM object
Find all <artist> elements that matches the name sent from the JavaScript
Output the album information (send to the "txtHint" placeholder)

AJAX can be used for interactive communication with a database.

AJAX Database Example

The following example will demonstrate how a web page can fetch information from a database with AJAX:

Example Explained - The MySQL Database

The database table we use in the example above looks like this:

id	FirstName	LastName	Age	Hometown	Job
1	Peter	Griffin	41	Quahog	Brewery
2	Lois	Griffin	40	Newport	Piano Teacher
3	Joseph	Swanson	39	Quahog	Police Officer
4	Glenn	Quagmire	41	Quahog	Pilot

Example Explained - The HTML Page

When a user selects a user in the dropdown list above, a function called "showUser()" is executed. The function is triggered by the "onchange" event:

<html>
<head>
<script type="text/javascript">
function showUser(str)
{
if (str=="")
{
document.getElementById("txtHint").innerHTML="";
return;
}
if (window.XMLHttpRequest)
{// code for IE7+, Firefox, Chrome, Opera, Safari
xmlhttp=new XMLHttpRequest();
}
else
{// code for IE6, IE5
xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
}
xmlhttp.onreadystatechange=function()
{
if (xmlhttp.readyState==4 && xmlhttp.status==200)
    {
    document.getElementById("txtHint").innerHTML=xmlhttp.responseText;
    }
}
xmlhttp.open("GET","getuser.php?q="+str,true);
xmlhttp.send();
}
</script>
</head>
<body>

<form>
<select name="users" onchange="showUser(this.value)">
<option value="">Select a person:</option>
<option value="1">Peter Griffin</option>
<option value="2">Lois Griffin</option>
<option value="3">Glenn Quagmire</option>
<option value="4">Joseph Swanson</option>
</select>
</form>
<br />
<div id="txtHint"><b>Person info will be listed here.</b></div>

</body>
</html>

The showUser() function does the following:

Check if a person is selected
Create an XMLHttpRequest object
Create the function to be executed when the server response is ready
Send the request off to a file on the server
Notice that a parameter (q) is added to the URL (with the content of the dropdown list)

The PHP File

The page on the server called by the JavaScript above is a PHP file called "getuser.php".
The source code in "getuser.php" runs a query against a MySQL database, and returns the result in an HTML table:

<?php
$q=$_GET["q"];

$con = mysql_connect('localhost', 'peter', 'abc123');
if (!$con)
  {
  die('Could not connect: ' . mysql_error());
  }

mysql_select_db("ajax_demo", $con);

$sql="SELECT * FROM user WHERE id = '".$q."'";

$result = mysql_query($sql);

echo "<table border='1'>
<tr>
<th>Firstname</th>
<th>Lastname</th>
<th>Age</th>
<th>Hometown</th>
<th>Job</th>
</tr>";

while($row = mysql_fetch_array($result))
  {
  echo "<tr>";
  echo "<td>" . $row['FirstName'] . "</td>";
  echo "<td>" . $row['LastName'] . "</td>";
  echo "<td>" . $row['Age'] . "</td>";
  echo "<td>" . $row['Hometown'] . "</td>";
  echo "<td>" . $row['Job'] . "</td>";
  echo "</tr>";
  }
echo "</table>";

mysql_close($con);
?>

Explanation: When the query is sent from the JavaScript to the PHP file, the following happens:

PHP opens a connection to a MySQL server
The correct person is found
An HTML table is created, filled with data, and sent back to the "txtHint" placeholder

AJAX :: PHP

AJAX PHP Example

The following example will demonstrate how a web page can communicate with a web server while a user type characters in an input field:

Example Explained - The HTML Page

When a user types a character in the input field above, the function "showHint()" is executed. The function is triggered by the "onkeyup" event:

<html>
<head>
<script type="text/javascript">
function showHint(str)
{
if (str.length==0)
{
document.getElementById("txtHint").innerHTML="";
return;
}
if (window.XMLHttpRequest)
{// code for IE7+, Firefox, Chrome, Opera, Safari
xmlhttp=new XMLHttpRequest();
}
else
{// code for IE6, IE5
xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
}
xmlhttp.onreadystatechange=function()
{
if (xmlhttp.readyState==4 && xmlhttp.status==200)
    {
    document.getElementById("txtHint").innerHTML=xmlhttp.responseText;
    }
}
xmlhttp.open("GET","gethint.php?q="+str,true);
xmlhttp.send();
}
</script>
</head>
<body>

<p><b>Start typing a name in the input field below:</b></p>
<form>
First name: <input type="text" onkeyup="showHint(this.value)" size="20" />
</form>
<p>Suggestions: <span id="txtHint"></span></p>

</body>
</html>

Source code explanation:
If the input field is empty (str.length==0), the function clears the content of the txtHint placeholder and exits the function.
If the input field is not empty, the showHint() function executes the following:

Create an XMLHttpRequest object
Create the function to be executed when the server response is ready
Send the request off to a file on the server
Notice that a parameter (q) is added to the URL (with the content of the input field)

The PHP File

The page on the server called by the JavaScript above is a PHP file called "gethint.php".
The source code in "gethint.php" checks an array of names, and returns the corresponding name(s) to the browser:

<?php
// Fill up array with names
$a[]="Anna";
$a[]="Brittany";
$a[]="Cinderella";
$a[]="Diana";
$a[]="Eva";
$a[]="Fiona";
$a[]="Gunda";
$a[]="Hege";
$a[]="Inga";
$a[]="Johanna";
$a[]="Kitty";
$a[]="Linda";
$a[]="Nina";
$a[]="Ophelia";
$a[]="Petunia";
$a[]="Amanda";
$a[]="Raquel";
$a[]="Cindy";
$a[]="Doris";
$a[]="Eve";
$a[]="Evita";
$a[]="Sunniva";
$a[]="Tove";
$a[]="Unni";
$a[]="Violet";
$a[]="Liza";
$a[]="Elizabeth";
$a[]="Ellen";
$a[]="Wenche";
$a[]="Vicky";

//get the q parameter from URL
$q=$_GET["q"];

//lookup all hints from array if length of q>0
if (strlen($q) > 0)
{
$hint="";
for($i=0; $i<count($a); $i++)
    {
    if (strtolower($q)==strtolower(substr($a[$i],0,strlen($q))))
      {
      if ($hint=="")
        {
        $hint=$a[$i];
        }
      else
        {
        $hint=$hint." , ".$a[$i];
        }
      }
    }
}

// Set output to "no suggestion" if no hint were found
// or to the correct values
if ($hint == "")
{
$response="no suggestion";
}
else
{
$response=$hint;
}

//output the response
echo $response;
?>

Explanation: If there is any text sent from the JavaScript (strlen($q) > 0), the following happens:

Find a name matching the characters sent from the JavaScript
If no match were found, set the response string to "no suggestion"
If one or more matching names were found, set the response string to all these names
The response is sent to the "txtHint" placeholder

AJAX :: introduction

AJAX is about updating parts of a web page, without reloading the whole page.

What is AJAX?

AJAX = Asynchronous JavaScript and XML.
AJAX is a technique for creating fast and dynamic web pages.
AJAX allows web pages to be updated asynchronously by exchanging small amounts of data with the server behind the scenes. This means that it is possible to update parts of a web page, without reloading the whole page.
Classic web pages, (which do not use AJAX) must reload the entire page if the content should change.
Examples of applications using AJAX: Google Maps, Gmail, Youtube, and Facebook tabs.

How AJAX Works

AJAX is Based on Internet Standards

AJAX is based on internet standards, and uses a combination of:

XMLHttpRequest object (to exchange data asynchronously with a server)
JavaScript/DOM (to display/interact with the information)
CSS (to style the data)
XML (often used as the format for transferring data)

AJAX applications are browser- and platform-independent!

Google Suggest

AJAX was made popular in 2005 by Google, with Google Suggest.
Google Suggest is using AJAX to create a very dynamic web interface: When you start typing in Google's search box, a JavaScript sends the letters off to a server and the server returns a list of suggestions.

Sunday, 10 July 2011

With PHP, it is possible to upload files to the server.

Create an Upload-File Form

To allow users to upload files from a form can be very useful.

Look at the following HTML form for uploading files:

<html>

<body>

<form action="upload_file.php" method="post"

enctype="multipart/form-data">

<label for="file">Filename:</label>

<input type="file" name="file" id="file" />

<br />

<input type="submit" name="submit" value="Submit" />

</form>

</body>

</html>

Notice the following about the HTML form above:

The enctype attribute of the <form> tag specifies which content-type to use when submitting the form. "multipart/form-data" is used when a form requires binary data, like the contents of a file, to be uploaded
The type="file" attribute of the <input> tag specifies that the input should be processed as a file. For example, when viewed in a browser, there will be a browse-button next to the input field

Note: Allowing users to upload files is a big security risk. Only permit trusted users to perform file uploads.

Create The Upload Script

The "upload_file.php" file contains the code for uploading a file:

<?php

if ($_FILES["file"]["error"] > 0)

  {

  echo "Error: " . $_FILES["file"]["error"] . "<br />";

  }

else

  {

  echo "Upload: " . $_FILES["file"]["name"] . "<br />";

  echo "Type: " . $_FILES["file"]["type"] . "<br />";

  echo "Size: " . ($_FILES["file"]["size"] / 1024) . " Kb<br />";

  echo "Stored in: " . $_FILES["file"]["tmp_name"];

  }

?>

By using the global PHP $_FILES array you can upload files from a client computer to the remote server.

The first parameter is the form's input name and the second index can be either "name", "type", "size", "tmp_name" or "error". Like this:

$_FILES["file"]["name"] - the name of the uploaded file
$_FILES["file"]["type"] - the type of the uploaded file
$_FILES["file"]["size"] - the size in bytes of the uploaded file
$_FILES["file"]["tmp_name"] - the name of the temporary copy of the file stored on the server
$_FILES["file"]["error"] - the error code resulting from the file upload

This is a very simple way of uploading files. For security reasons, you should add restrictions on what the user is allowed to upload.

Restrictions on Upload

In this script we add some restrictions to the file upload. The user may only upload .gif or .jpeg files and the file size must be under 20 kb:

<?php

if ((($_FILES["file"]["type"] == "image/gif")

|| ($_FILES["file"]["type"] == "image/jpeg")

|| ($_FILES["file"]["type"] == "image/pjpeg"))

&& ($_FILES["file"]["size"] < 20000))

  {

  if ($_FILES["file"]["error"] > 0)

    {

    echo "Error: " . $_FILES["file"]["error"] . "<br />";

    }

  else

    {

    echo "Upload: " . $_FILES["file"]["name"] . "<br />";

    echo "Type: " . $_FILES["file"]["type"] . "<br />";

    echo "Size: " . ($_FILES["file"]["size"] / 1024) . " Kb<br />";

    echo "Stored in: " . $_FILES["file"]["tmp_name"];

    }

  }

else

  {

  echo "Invalid file";

  }

?>

Note: For IE to recognize jpg files the type must be pjpeg, for FireFox it must be jpeg.

Saving the Uploaded File

The examples above create a temporary copy of the uploaded files in the PHP temp folder on the server.

The temporary copied files disappears when the script ends. To store the uploaded file we need to copy it to a different location:

<?php

if ((($_FILES["file"]["type"] == "image/gif")

|| ($_FILES["file"]["type"] == "image/jpeg")

|| ($_FILES["file"]["type"] == "image/pjpeg"))

&& ($_FILES["file"]["size"] < 20000))

  {

  if ($_FILES["file"]["error"] > 0)

    {

    echo "Return Code: " . $_FILES["file"]["error"] . "<br />";

    }

  else

    {

    echo "Upload: " . $_FILES["file"]["name"] . "<br />";

    echo "Type: " . $_FILES["file"]["type"] . "<br />";

    echo "Size: " . ($_FILES["file"]["size"] / 1024) . " Kb<br />";

    echo "Temp file: " . $_FILES["file"]["tmp_name"] . "<br />";

    if (file_exists("upload/" . $_FILES["file"]["name"]))

      {

      echo $_FILES["file"]["name"] . " already exists. ";

      }

    else

      {

      move_uploaded_file($_FILES["file"]["tmp_name"],

      "upload/" . $_FILES["file"]["name"]);

      echo "Stored in: " . "upload/" . $_FILES["file"]["name"];

      }

    }

  }

else

  {

  echo "Invalid file";

  }

?>

The script above checks if the file already exists, if it does not, it copies the file to the specified folder.

Note: This example saves the file to a new folder called "upload"