code-diesel » php

‘isset’ construct and multiple parameters

sameer — Sat, 30 Jan 2010 10:44:09 +0000

PHP programmers are frequently into using the various is_x group of functions: is_int, is_null etc. All of this functions take a single parameter which leads you to believe that other similar constructs take only a single parameter. Like the isset and unset constructs, which by the way take multiple parameters as shown below, which might help you save some keystrokes.

So instead of writing:

$var1 = 'a';
$var2 = 'b';
$var3 = 'c';
$var4 = 'd';
 
if(isset($var1) && isset($var2) && isset($var3) && isset($var4))
{
    // All variables are set, do something
}

We can write:

$var1 = 'a';
$var2 = 'b';
$var3 = 'c';
$var4 = 'd';
 
if(isset($var1, $var2, $var3, $var4))
{
    // Will return TRUE only if all of the parameters are set
}

Same with the unset() construct:

unset($var1, $var2, $var3, $var4);

Creating custom stream filters

sameer — Mon, 15 Jun 2009 13:49:47 +0000

In this post we will see how to create a custom stream filter. Streams, first introduced in PHP 4.3, provide an abstration layer for file access. A number of different resources besides files – like network connections, compression protocols etc. can be regarded as “streams” of data which can be serially read and written to.

By default there are a number of filters registered with PHP. You can get the list of filters registered on your system by the following call:

print_r (stream_get_filters());

On my system it returns the following registered filters.

Array
(
    [0] => convert.iconv.*
    [1] => string.rot13
    [2] => string.toupper
    [3] => string.tolower
    [4] => string.strip_tags
    [5] => convert.*
    [6] => consumed
    [7] => zlib.*
    [8] => bzip2.*
)

For example to strip html tags from a input string you add the ‘string.strip_tags’ filter to the stream resource as below.

$html = 'The World is safe again.';
 
$fp = fopen("php://output", "r");
stream_filter_prepend($fp, "string.strip_tags");
fwrite($fp, $html);
fclose($fp);

Which will than output:

The World is safe again.

Creating a custom filter
In this section we will create a filter to replace urls in the input stream with a
‘[----URL----]‘ string. Now this may not look like much of a helpful filter, but this is just for illustrative purpose. You can use any replacement string you like. The complete source for the filter class is shown below.


 
class URLFilter extends PHP_User_Filter
{
    private $_data;
 
    /* Called when the filter is initialized */
    function onCreate( )
    {
        $this->_data = '';
        return true;
    }
 
    /* This is where the actual stream data conversion takes place */
    public function filter($in, $out, &$consumed, $closing)
    {
 
        /* We read all the stream data and store it in 
           the '$_data' variable 
        */
        while($bucket = stream_bucket_make_writeable($in))
        {
            $this->_data .= $bucket->data;
            $this->bucket = $bucket;
            $consumed = 0;
        }
 
        /* Now that we have read all the data from the stream we process 
          it and save it again to the bucket.
        */
        if($closing)
        {
            $consumed += strlen($this->_data);
 
            $pattern = "#http(s)?://([\w-]+\.)+[\w-]+(/[\w-./?%&=]*)?#";
            $str = preg_replace($pattern,
                                '[----URL----]',
                                $this->_data);
 
            $this->bucket->data = $str;
            $this->bucket->datalen = strlen($this->_data);
 
            if(!empty($this->bucket->data))
                stream_bucket_append($out, $this->bucket);
 
            return PSFS_PASS_ON;
        }
 
        return PSFS_FEED_ME;
    }
}
 
?>

All the action takes place in the filter() method, where we collect all the data from the buckets. The data is retrieved in the fashion of a bucket brigade. The stream_bucket_make_writable() function reads a portion of the data from the input bucket and converts it to a PHP bucket object. The data property of the bucket object is a string holding the bucket’s data, whereas datalen stores its length. We could convert the data in the filter() function itself, but rather we store all the data retrieved in the $_data variable and convert it at a single go.

Once all the data from the stream is read the $closing parameter is set to true. Now we can check for that and than process the data in any fashion we like. Once the data processing is done we add the processed data to the bucket and return a PSFS_PASS_ON to imply that we have successfully processed the stream data.

An Example
Before we use the filter we have to register the filter and append it to the stream. A example using the above class is shown below, which gets the content from Google.com and than replaces all the urls in the source with the ‘[----URL----]‘ string.

 
stream_filter_register('myFilter', 'URLFilter');
$handle = fopen("http://www.google.com/", "r");
stream_filter_append($handle, "myFilter");
 
while (!feof($handle))
{
  $contents .= fread($handle, 8192);
}
 
fclose($handle);
echo $contents;

Validating POST fields the easy way

sameer — Fri, 12 Dec 2008 15:47:44 +0000

Validating POST data from a form is a common requirement for a developer. If the number of form fields are few than the validation is a small matter. But the case is different when the form contains more than 15 or 20 fields and some of the fields are mandatory. The following code will give you an idea of how to easily validate mandatory fields, whatever the number of fields.

The first step is to prefix a ‘c_’ or any other character of your choice to a form field that is mandatory. For example I’ve prefixed a ‘c_’ for the email field below.

<input name="c_email" id="c_email" maxlength="40" type="text" />

Once we have added the required prefix we can check for them using the following code.

/* Initialize $_SESSION variables to hold errors and form variables */
$_SESSION['formVars'] = array();
$_SESSION['errors'] = array();
 
/* Copy all $_POST variables to $_SESSION['formVars'] */
foreach($_POST as $varname=>$value) 
{
    /**
     * For form elements that are compulsory check 
     * to see if they are empty. To ease this ,form 
     * elements that are compulsory have a 'c_' prefix added,
     * we can use that to parse the compulsory fields.
     **/
 
     /* Get the field prefix */
    $prefix = substr($varname, 0, 2);
 
    if(empty($_SESSION['formVars'][$varname]) && $prefix == "c_")
        $_SESSION['errors'][$varname] = substr($varname, 2, strlen($varname) - 2) . " field cannot be empty";
}

Now it doesn’t matter how many form fields you have, the code remains the same. You can extend the idea for other validation purpose. For example you can add a double prefix like ‘ci_” to indicate that the field is mandatory with a integer datatype and make the corresponding change in the validation code.

Creating a Figlet text in php

sameer — Tue, 18 Nov 2008 12:21:27 +0000

Zend_Text_Figlet is a Zend component which enables developers to create a FIGlet text. A Figlet is nothing but a technique of creating large letters using ordinary text. I don’t know how to make a use of this in my daily matters, but its a nice recreation. A short history on Figlet can be found here. An example and the code to generate it is shown below.

  ____     __   _     ____
 |  _ \\  | || | ||  |  _ \\
 | |_| || | '--' ||  | |_| ||
 | .__//  | .--. ||  | .__//
 |_|--`   |_|| |_||  |_|--`
 `-`      `-`  `-`   `-`


 
require_once("zend/text/figlet.php");
$figlet = new Zend_Text_Figlet();
echo $figlet->render('PHP');
 
?>

If you are displaying the output on a web page make sure to use the ‘pre’ tags around the Figlet. The Figlet looks good in a pure text format.
You can also define various options for the Figlet by passing the function an array of options, like say changing the font.


 
require_once("zend/text/figlet.php");
/* use a different font */
$options = array('font' => 'graffiti.flf');               
 
$figlet = new Zend_Text_Figlet($options);
echo $figlet->render('PHP');
 
?>

__________   ___ ___  __________
\______   \ /   |   \ \______   \
 |     ___//    ~    \ |     ___/
 |    |    \    Y    / |    |
 |____|     \___|_  /  |____|
                  \/

You can download more fonts from here.
The default width of the Figlet output is set to 80 characters, which you can change with the ‘outputWidth’ option.

.
.
$options = array('outputWidth' => 120);

For more options you can take a look at the documentation.

Easy way to build GET query strings in php

sameer — Thu, 13 Nov 2008 14:10:58 +0000

Passing variables with a url is such a frequent thing programmers do that most of you may think this post is unwarranted. We call this method of passing variables as GET, the other being POST. It is one of those things which can be easily done in php. Lets take an example. You are to query a database and for that you need to send three variables via GET – city, id, paid.
The common way to pass them via GET is to construct a query string as below:

/* assume we want to pass this variables */
$city_name = "new york";
$invoice_id = 3456;
$paid = 1;
 
$query_string = "city={$city_name}&id={$invoice_id}&paid={$paid}";
$url = "http://www.example.com?" . $query_string;

The problem is that most php programmers get stuck using the above method. The method is fine for three to four variables, but for more than that the code gets hard to read and maintain, introducing subtle bugs in the constructed query.

The best way to pass GET variables is to use the http_build_query() function available from php version 5; which takes an array of variables and builds a nice URL encoded string which you can append to a url. And example is shown below.

$city_name = "new york";
$invoice_id = 3456;
$paid = 1;
 
$fields = array('city' => $city_name,
                'id' => $invoice_id,
                'paid' => $paid);
 
$url = "http://www.example.com?" . http_build_query($fields, '', "&");

In the above example the array contained the variable names and their values. You can also pass an array containing only values and let the function fill the variable name using the array index and a variable you supply (as a second parameter). For example if you want to pass an array of six cities than you can do the following, the second parameter of the function being the query variable.

$fields = array('paris',
                'new york',
                'florence',
                'london',
                'berlin',
                'delhi');
 
$url = "http://www.example.php?" .
        http_build_query($fields, 'city', "&");

The generated url will look like this:

http://www.example.php/?city0=paris&city1=new+york&city2=florence&city3=london&city4=berlin&city5=delhi

The third parameter to the function is not necessary as the function defaults to using ‘&’ as a separator. But I prefer making it explicit.
You can also easily pass a complex array as below:

$city_name      = "new york";
$invoice_id     = 3456;
$currency_name  = "euro";
$total          = 345;
$receipt_no     = "fgf44545";
 
$fields = array('city' => $city_name,
                'id' => $invoice_id,
                'paid' => array('currency' => $currency_name,
                                'amount' => $total,
                                'receipt' => $receipt_no)                
                );
 
$url = "http://www.example.php?" .
        http_build_query($fields, '', "&");

Which will create a url encoded query as following:

http://www.example.com?city=new+york&id=3456&paid%5Bcurrency%5D=euro&paid%5Bamount%5D=345&paid%5Breceipt%5D=fgf44545

To go the reverse way, we can parse the encoded url above using the code below:

$url_to_parse = "http://www.example.com?city=new+york&id=3456&paid%5Bcurrency%5D=euro&paid%5Bamount%5D=345&paid%5Breceipt%5D=fgf44545";
$parsed_url = parse_url($url_to_parse);
print_r($parsed_url);
 
/* This will output the following array */
Array
(
    [scheme] => http
    [host] => www.example.com
    [query] => city=new+york&id=3456&paid%5Bcurrency%5D=euro&paid%5Bamount%5D=345&paid%5Breceipt%5D=fgf44545
)

Now we can further parse the url query string stored in the ‘query’ variable above:

$url_query = $parsed_url['query'];
parse_str($url_query, $out);
print_r($out);
 
/* This will output the following array */
Array
(
    [city] => new york
    [id] => 3456
    [paid] => Array
        (
            [currency] => euro
            [amount] => 345
            [receipt] => fgf44545
        )
 
)

As can be seen the http_build_query() function really makes constructing GET queries simple.

Simple Pagination in PHP tutorial

sameer — Fri, 24 Oct 2008 05:03:48 +0000

Pagination is a frequent requirement in web development projects. Most PHP developers must have already implementated paging in one form or other in their projects. In this post we will see how to add pagination the easy way using PEAR’s Pager class. Note that in all the posts I use PHP 5.x.x, so if you are still stuck at version 4.x.x, its already time to upgrade.

Its always nice to see some working code first, before getting into the details. So here goes.

require_once 'Pager/Pager.php';
/* We will bypass the database connection code ... */
$sqlQuery = "SOME SQL QUERY";
$result = mysql_query($sqlQuery);
$totalRows = mysql_num_rows($result);
 
$pager_options = array(
'mode'       => 'Sliding',
'perPage'    => 10,
'delta'      => 4,
'totalItems' => $totalRows,
);
$pager = Pager::factory($pager_options);
echo $pager->links;

The above code will return the following pagination links.

1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 » [10]

Assuming the page where the above code is included is named ‘dataPage.php’; the pager links will have a url like follows:

dataPage.php?pageID=n

where n is the page number.

You can see how easy it is using the Pager class. All the link building is handled by the class. Now lets go into the details.

1. Installation

If you are installing using the Pear installer, enter the following at the command prompt to install Pager.

c:\pear install Pager

Or else you can just download the module from here and then copy it to your Pear includes directory, which will probably be ‘c:\your php installation directory\Pear’.

2. A simple example

In the following example we will create a pagination for a ‘logs’ table.

/* Include the Pear::Pager file */
require_once ('Pager/Pager.php');
 
/* Replace this with your database details */
$connection = mysql_connect("localhost", username, password);
mysql_select_db(database name, $connection);
 
/* First we need to get the total rows in the table */
$result=mysql_query("SELECT count(*) AS total FROM logs", $connection);
$row = mysql_fetch_array($result);
 
/* Total number of rows in the logs table */
$totalItems = $row['total'];
 
/* Set some options for the Pager */
$pager_options = array(
'mode'       => 'Sliding',   // Sliding or Jumping mode. See below.
'perPage'    => 10,   // Total rows to show per page
'delta'      => 4,   // See below
'totalItems' => $totalItems,
);
 
/* Initialize the Pager class with the above options */
$pager = Pager::factory($pager_options);
 
/* Display the links */
echo $pager->links;
 
/* The following code will retreive the result using the pager options */
 
/* The function below will get the page offsets to be used with
the database query. For e.g if we are on the third page then the
$from variable will have the value of '21' (we are showing 10 items per 
page, remember) and the $to variable will have the value of '30'.
*/
list($from, $to) = $pager->getOffsetByPageId();
/* The MySQL 'LIMIT' clause index starts from '0', 
    so decrease the $from by 1 */
$from = $from - 1;
 
/* The number of rows to get per query */
$perPage = $pager_options['perPage'];
 
$result = mysql_query("SELECT * FROM alogs LIMIT $from , $perPage",
$connection);
 
while($row = mysql_fetch_array($result))
{
/* Do something with the query results */
}

In the Pager class there are two modes to display the pagination: Sliding & Jumping.

With Pager in “Sliding” mode the pagination links change smoothly, and the current page is always shown at the center of the “window” (except for the start and end pages). When in Sliding mode the delta option implies how many links to show on the left and right of the current page link.
For e.g with a delta set to ’3′ the links are displayed as shown below, page 10 being the current page:

[1] « 7 | 8 | 9 | 10 | 11 | 12 | 13 » [13]

With delta option set to ’4′ the links are shown as below. As you can see there are four links to the left and right of the current page.

[1] « 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 » [13]

With the Pager in “Jumping” mode and delta set to ’4′ the Pager always shows the same 4 page links while you are on one of these pages.
For e.g with a delta set to ’4′ the links are displayed as shown below, page 5 being the current page:

[1] << Back 5 6 7 8 Next >> [13]

If you are on page ’9′ the links displayed are as below:

[1] << Back 9 10 11 12 Next >> [13]

3. More options

You can also change the default separator to any character or image you like.

$pager_options = array(
'mode'       => 'Sliding',
'perPage'    => 10,
'delta'      => 4,
'separator' => ',',
'totalItems' => $totalItems,
);

This will output the following:
[1] « 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 » [13]

If you would like to add images to the ‘next’ and ‘previous’ links, use the following options:

$pager_options = array(
'mode'       => 'Sliding',
'perPage'    => 10,
'delta'      => 4,
'nextImg'    => '',
'prevImg'    => '',
'totalItems' => $totalItems,
);

Which will display the links as shown below:

The default number of spaces before each separator is three. To change the number of spaces use the ‘spacesBeforeSeparator’ option. For e.g:

.
.
'spacesBeforeSeparator' => 1,
.

4. Styling

You can style the links by putting them in a div tag and applying a css. A example css and its output is shown below.

Add a div tag:

.
.
echo '';
echo $pager->links;
echo '
';

Apply CSS:

.pager {
    font-family: Arial;
    font-size: 14px;
}
 
.pager a {
    font-family: Arial;
    font-size: 14px;
    text-decoration: none;
    width: 17px;
    height: 17px;
    border: 1px solid #000;
    background-color: #0C74BA;
    text-align: center;
    color: #fff;
}
 
.pager a:hover {
    background-color: #c0c0c0;
}

The output:

That’s it. There are many other options you can use with the Pager class, the details which you can find in the Pager documentation.

WHOIS directory lookup in PHP

sameer — Sat, 13 Sep 2008 12:23:11 +0000

Net_Whois lets you query a internet name directory service in a easy to use manner. WHOIS is a protocol which is widely used to determine the owner of a domain name, an IP address by querying an official name database. One possible application I can think of is to see if DNS servers are set correctly for various domains I handle regularly.

Installation

Net_Whois being a Pear package we will use the Pear installer as below. I recommend to always use the Pear installer to download packages rather than downloading it manually as the Pear installer automatically downloads any dependent packages.

pear install Net_Whois-1.0.2

Usage

The current library uses the following servers to execute the query:
whois.crsnic.net
whois.networksolutions.com
whois.nic.mil
whois.nic.gov
whois.arin.net
whois.ripe.net
whois.apnic.net
whois.ripn.net
whois.ra.net
.whois-servers.net
whois.6bone.net
whois.registro.br

A example code is shown below.


 
    require_once "Net/Whois.php";
 
    $whois = new Net_Whois();
    /* You can add other NIC server as a second parameter. */
    $info = $whois->query('example.com');
    echo($info);
 
?>

Note that the class returns a string, so you would need to use regular expressions to get to the relevant information.

Ping a server using PHP

sameer — Sat, 13 Sep 2008 11:58:05 +0000

PEAR’s Net_Ping is a niffty wrapper class for executing ping calls from PHP. You can use it to check if a remote server is responding correctly. The library can be download from here.

Installation

Net_Ping being a Pear package we will use the Pear installer to download and install it. I recommend to always use the Pear installer to download packages rather than downloading it manually as the Pear installer automatically downloads any dependent packages.

pear install Net_Ping-2.4.4

Usage

A example of using Net_Ping is given below.


 
    require_once "Net/Ping.php";
 
    $ping = Net_Ping::factory();
 
    if(PEAR::isError($ping))
      echo $ping->getMessage();
    else
    {
      /* Number of packets to send */
      $ping->setArgs(array('count' => 4));
      $rawData = $ping->ping('google.com');
      print_r($rawData);
    }
 
?>

The output of the same is shown below.

Net_Ping_Result Object
(
    [_icmp_sequence] => Array
        (
            [1] => 310
            [2] => 300
            [3] => 318
            [4] => 301
        )
 
    [_target_ip] => 64.233.167.99
    [_bytes_per_request] => 32
    [_bytes_total] => 128
    [_ttl] => 238
    [_raw_data] => Array
        (
            [0] => 
            [1] => Pinging google.com [64.233.167.99] with 32 bytes of data:
            [2] => 
            [3] => Reply from 64.233.167.99: bytes=32 time=310ms TTL=238
            [4] => Reply from 64.233.167.99: bytes=32 time=300ms TTL=238
            [5] => Reply from 64.233.167.99: bytes=32 time=318ms TTL=238
            [6] => Reply from 64.233.167.99: bytes=32 time=301ms TTL=238
            [7] => 
            [8] => Ping statistics for 64.233.167.99:
            [9] =>     Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
            [10] => Approximate round trip times in milli-seconds:
            [11] =>     Minimum = 300ms, Maximum = 318ms, Average = 307ms
        )
 
    [_sysname] => windows
    [_round_trip] => Array
        (
            [min] => 300
            [max] => 318
            [avg] => 307
        )
 
    [_transmitted] => 4
    [_received] => 4
    [_loss] => 0
)

Reading raw POST data in PHP

sameer — Fri, 12 Sep 2008 07:00:55 +0000

A quick tip for reading raw http POST data in PHP. For example if we have a xml posted to a page, we can read the raw data with the following code.

$xml = file_get_contents('php://input');

We could use $HTTP_RAW_POST_DATA instead, but many times it does not work due to some php.ini settings. Note that ‘php://input’ does not work with enctype=”multipart/form-data”.

converting MySQL queries to xml

sameer — Tue, 05 Aug 2008 13:00:51 +0000

There frequently arises a need to return mySQL query results in xml. Maybe you need to send the xml data to the browser or you want to use it as a xml request to a web service; whatever the application, the following function will return the result of a sql query in xml format.

The function accepts 3 parameters. The first is the mysql query result resource, the second is the name of the root element and the third the name of the first child of the root. All the fields from the mySQL table will be sub elements of this child.

The function is shown below:

/**
 * @param mysql_resource - $queryResult - mysql query result
 * @param string - $rootElementName - root element name
 * @param string - $childElementName - child element name
 */
function sqlToXml($queryResult, $rootElementName, $childElementName)
{ 
    $xmlData = "\"1.0\" encoding=\"ISO-8859-1\" ?>\n"; 
    $xmlData .= "<" . $rootElementName . ">";
 
    while($record = mysql_fetch_object($queryResult))
    { 
        /* Create the first child element */
        $xmlData .= "<" . $childElementName . ">";
 
        for ($i = 0; $i < mysql_num_fields($queryResult); $i++)
        { 
            $fieldName = mysql_field_name($queryResult, $i); 
 
            /* The child will take the name of the table column */
            $xmlData .= "<" . $fieldName . ">";
 
            /* We set empty columns with NULL, or you could set 
                it to '0' or a blank. */
            if(!empty($record->$fieldName))
                $xmlData .= $record->$fieldName; 
            else
                $xmlData .= "null"; 
 
            $xmlData .= " . $fieldName . ">"; 
        } 
        $xmlData .= " . $childElementName . ">"; 
    } 
    $xmlData .= " . $rootElementName . ">"; 
 
    return $xmlData; 
}

How to use?
For example if we have a ‘company’ table with the following three fields:
id, companyid, name.

You can use the above function in the following manner to convert the table rows into xml;

.
.
/* Sql query */
$result = mysql_query("SELECT * from company");
 
/* If you want to process the returned xml rather than send it
    to the browser, remove the below line.
*/
header("Content-Type: application/xml");
echo sqlToXml($result, "companies", "company");

which returns the following xml.

 version="1.0" encoding="ISO-8859-1" ?>
>
	>
		>1>
		>1>
		>microsoft>
        >
.
.
.
>