Examples


As is the case with other matters, you will need to check with your server administration to find out the ways in which the PHP installation accesses XML, because there is more than one way. The approach shown here requires you to define functions for handling different categories of tags. The categories are starting tags, ending tags, and character data tags. The action of the functions is to output to the browser fragments of HTML. This is not unlike what you did with PHP and ASP in previous chapters. However, the requirements of handling XML mean the tasks are divided differently. You need to think about what action is to be triggered by the start of an element, the contents of an element, and then close of an element.

The assumption is that the XML documents contain tags of the following structure:

    <contact>     <name>John Doe </name>     <email>john.doe@xxx.yyy</email>     </contact>

The XML file could contain other tags, but these are the only ones recognized by this PHP script. The PHP script, shown in Table 17.1, will produce an HTML table, with a new row for each contact.

Table 17.1: PHP Code Handling XML Data

<html><head><title>PHP xml SAX test </title>

HTML starting tags

<style type="text/css">

Style section

td {font-family: Arial; font-size: smaller}

Style for table elements

h2 {font-family: Comic Sans MS}

Style for type h2 heading

</style>

End of style section

</head>

End of head section

<body>

Start of body

<h2>Address book </h2><p>

Heading

<table border="1"><tr><td>Name</td><td>E-mail</td></tr>

Start of table

<?

Start of PHP

$file="D:\inetpub\wwwroot\jeanine\ xmlstuff\contactsnoref.xml";

Address for xml file

$currenttag="";

Variable holding current tag

function startElement($parser,$name, $attrs) {

Function definition. This function will be cited later

global $currenttag;

Will use the global variable

$currenttag=$name;

Sets $currenttag to be the $name passed as argument for call of function

switch($name) {

Switch statement

case "CONTACT":

For the contact case…

print("<tr>");

Start a new row

break;

Break out of the switch statement

case "NAME":

For the name case…

print("<td>");

Start a new table datum (new column)

break;

Break out of the switch statement

case "EMAIL":

For the e-mail case

print("<td>");

Start a new table datum

break;

Break out of the switch statement

default:

All other cases… (this line and the next could be omitted, but is a placeholder in case you need to add something later)

break;

Break out of switch

}

End of switch

}

End of function

function endElement($parser,$name) {

Start of function. This function will be cited later

global $currenttag;

Will use global variable

switch ($name) {

Switch statement

case "CONTACT":

For contact case

print("</tr>");

End row of table

break;

Break out of switch

case "NAME":

For name case

print ("</td>");

End table datum

break;

Break out of switch

case "EMAIL":

For e-mail case

print("</td>");

End table datum

break;

Break out of switch

default:

Default case

break;

Break out of switch

}

End of switch

$currenttag="";

Reset variable to empty

}

End of function definition

function characterData($parser,$data){

Definition of function. This function is cited later

global $currenttag;

Will use global variable

switch($currenttag){

The global variable $currenttag is what guides the cases

case "NAME":

For name case

print("<b>" . $data . "</b>");

Output character data; namely, the contents of the tag in bold

break;

Break out of switch

case "EMAIL":

For the e-mail case

print($data);

Output the contents of the tag

break;

Break out of switch

default:

Default case

break;

Break out of switch

}

End of switch

}

End of function

$xml_parser=xml_parser_create();

Calls one of the built-in PHP functions for handling XML to define a parser object

xml_set_element_handler($xml_parser, "startElement","endElement");

Calls another of the built-in PHP functions to specify how starting and ending elements are to be handling by citing the functions just defined

xml_set_character_data_handler($xml_parser,"characterData");

Calls yet another of the built-in PHP functions to specify how character data is to be handled

if (!($fp=fopen($file,"r"))) {

Error handling: if the XML file cannot be located

die("Cannot locate XML data file: $file");

The die command ends the PHP script

}

Ends if clause

while ($data=fread($fp,4096))

Starts a while statement that reads the file. The parameter specifies a maximum number of characters

{ if (!xml_parse($xml_parser,$data, feof($fp))) {

If the XML contents end prematurely

die(sprintf("XML error: %s at %d", ($xml_parser)),

Signal error and close PHP scriptxml_error_string(xml_get_error_code

xml_get_current_line_number($xml_parser))); }

Continuation with output of line with error

}

xml_parser_free($xml_parser);

Release the object created for doing the parsing

?>

End PHP

</table></body></html>

Closing HTML tags

The code contains switch statements. These are the PHP versions of case conditional statements. In the PHP version, it is necessary to use a break command to exit the switch statement at the end of the particular case when you do not want to drop in to the following case. Notice that the $currenttag variable is set in one function and used in another.




Creating Database Web Applications with PHP and ASP
Creating Database Web Applications with PHP and ASP (Charles River Media Internet & Web Design)
ISBN: 1584502649
EAN: 2147483647
Year: 2005
Pages: 125
Authors: Jeanine Meyer

Similar book on Amazon

flylib.com © 2008-2017.
If you may any questions please contact us: flylib@qtcs.net