AJAX and PHP

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T Server-Side Techniques with PHP and MySQL It is important to keep an eye on the Apache error log when your PHP script behaves strangely. The default location and name of this file is Apache2\logs\error.log, and it can save you from many headaches. After setting the error-handling routine, we set the content type to XML, and divide the first received number by the second number. Note the usage of $_GET T to read the variables sent using GET. If you sent your variables using POSTT you should have used $_POST. Alternatively, you can use $_REQUEST, which finds variables sent with any method (including cookies); but it is generally recommended to avoid using it because it is a bit slower than the others. // specify that we are outputting an XML document header('Content-Type: text/xml'); // calculate the result $firstNumber = $_GET['firstNumber']; $secondNumber = $_GET['secondNumber']; $result = $firstNumber / $secondNumber; The division operation will generate an error if $secondNumber is 0. In this case, we expect the error-handler script to intercept the error. Note that in a real-world the situation, the professional way would be to check the value of the variable before calculating the division, but in this case we are interested in checking the error-handling script. After calculating the value, you package it into a nice XML document and output it, just as in the previous exercise: // create a new XML document $dom = new DOMDocument(); // create the root element and add it to the document $response = $dom->createElement('response'); $dom->appendChild($response); // add the calculated sqrt value as a text node child of $responseText = $dom->createTextNode($result); $response->appendChild($responseText); // build the XML structure in a string variable $xmlString = $dom->saveXML(); // output the XML string echo $xmlString; ?> Let's now have a look at the error-handling script—error_handler.php. This file has the role of intercepting any error messages generated by PHP, and outputting an error message that makes sense, and can be displayed by your JavaScript code: Figure 3.4: Good Looking Error Message 76 www.it-ebooks.info
Chapter 3 Without the customized error handler, the error message you will get would be: Figure 3.5: Bad Looking Error Message The error message will look like Figure 3.5 if the display_errors option in php.ini is On. By default, that option is Off and the errors are logged just in the Apache error log, but while writing code it may help to make them be displayed as well. If the code was production code, both error messages would have been inappropriate. You should never show such debugging information to your end users. So what happens in error_handler.php? First, the file uses the set_error_handler function to establish a new error-handling function: 77 www.it-ebooks.info
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AJAX and PHP Building Responsive We
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About the Authors Cristian Darie is
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About the Reviewers Emilian Balanes
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Table of Contents Preface 1 Chapter
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Table of Contents Chapter 6: AJAX S
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Preface AJAX is a complex phenomeno
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Preface What You Need for This Book
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Preface Errata Although we have tak
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1 AJAX and the Future of Web Applic
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Chapter 1 Because end-user satisfac
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Chapter 1 Three points for you to k
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Chapter 1 With JavaScript, develope
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interrupting the user from his or h
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• Creating simple online chat sol
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Chapter 1 done typing. (This method
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Chapter 1 All exercises from this b
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etrieve the user name $name = $_GET
Page 37 and 38: Chapter 1 If you're curious to test
Page 39 and 40: Chapter 1 request. In our case, thi
Page 41 and 42: 2 Client-Side Techniques with Smart
Page 43 and 44: AJAX Foundations: JavaScript and
Page 45 and 46: Chapter 2 • Because there is no s
Page 47 and 48: Time for Action—Using JavaScript
Page 49 and 50: Even More DOM In the previous exerc
Page 51 and 52: Chapter 2 What Just Happened? Well,
Page 53 and 54: Chapter 2 font-size: 10pt; } .Table
Page 55 and 56: Chapter 2 Creating the XMLHttpReque
Page 57 and 58: Chapter 2 You could, for example, c
Page 59 and 60: You will learn the most interesting
Page 61 and 62: Chapter 2 The safer version of proc
Page 63 and 64: Chapter 2 4. Create a file call
Page 65 and 66: Chapter 2 Figure 2.6: The Four HTTP
Page 67 and 68: Chapter 2 } } else { // display sta
Page 69 and 70: Chapter 2 } { // try to create XMLH
Page 71 and 72: Chapter 2 The responseXML method of
Page 73 and 74: Chapter 2 Figure 2.10: Opera Displa
Page 75 and 76: I admit that the following piece of
Page 77 and 78: 3 Server-Side Techniques with PHP a
Page 79 and 80: Chapter 3 } for (var i=0; i
Page 81 and 82: Chapter 3 // create the element $b
Page 83 and 84: Chapter 3 // create the root eleme
Page 85 and 86: Chapter 3 // read a file from the s
Page 87: Chapter 3 Figure 3.3: PHP Parameter
Page 91 and 92: } } // display the error in case of
Page 93 and 94: Chapter 3 Figure 3.7: Connecting to
Page 95 and 96: Chapter 3 } } // continue only if H
Page 97 and 98: Chapter 3 You can make Firefox list
Page 99 and 100: Chapter 3 } "MSXML2.XMLHTTP.4.0", "
Page 101 and 102: 'TEXT: ' . $errStr . chr(10) . 'LOC
Page 103 and 104: etrieve the parameters $num = 1; //
Page 105 and 106: Chapter 3 Figure 3.16: Flowchart De
Page 107 and 108: } Chapter 3 // only continue if xml
Page 109 and 110: } throw(response.length == 0 ? "Ser
Page 111 and 112: function process() { // ... if (req
Page 113 and 114: Chapter 3 Working with MySQL A back
Page 115 and 116: Chapter 3 Figure 3.17: Executing SQ
Page 117 and 118: Chapter 3 SELECT user_id, user_name
Page 119 and 120: 3. In your foundations folder, crea
Page 121 and 122: Chapter 3 After these commands exec
Page 123 and 124: Chapter 3 • friendly.php is a PHP
Page 125 and 126: This example requires a JavaSc
Page 127 and 128: } } // try to connect to the server
Page 129 and 130: Chapter 3 } // create HTML-formatte
Page 131 and 132: Chapter 3 On the server side, all t
Page 133 and 134: 4 AJAX Form Validation Validating i
Page 135 and 136: Chapter 4 Always validate user inpu
Page 137 and 138: Chapter 4 Figure 4.4: Successful Su
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Chapter 4 .left { margin-left: 150p
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Chapter 4 value="" />
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Registration Successfull! <<
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Chapter 4 } } { // display error me
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Chapter 4 require_once ('config.php
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Chapter 4 } { } $_POST['txtBthDay']
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Chapter 4 } } ?> return ($value ==
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Chapter 4 The field ID and value re
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Chapter 4 If we are dealing with cl
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5 AJAX Chat We are living in a worl
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Chapter 5 Implementing AJAX Chat We
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Chapter 5 // default the last id to
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} Chapter 5 ' DATE_FORMAT(posted_on
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Chapter 5 AJAX Chat Your b
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* function called when the Send but
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} } // retrieve the arrays from the
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Chapter 5 } } } // call server asyn
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Chapter 5 If you analyze the code f
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The business logic behind chat.php
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6 AJAX Suggest and Autocomplete Sug
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Chapter 6 The clever part of the Ja
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Chapter 6 6. Create another file na
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Chapter 6 { } a { } font-weight: bo
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Chapter 6 } { // try to create XMLH
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Chapter 6 } } } } { } displayError(
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Chapter 6 div += "" + "" + crtFunct
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} } // select the new suggestion an
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Chapter 6 } } else // FF if (oText.
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Chapter 6 Figure 6.4: PHP Documenta
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Chapter 6 We have talked about cach
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Chapter 6 visible, we need to scrol
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7 AJAX Real-Time Charting with SVG
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Chapter 7 Figure 7.1: SVG Chart The
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Chapter 7 Figure 7.2: SVG Charting
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Chapter 7 } { xmlHttp.onreadystatec
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} } // sets the X and Y attributes
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Chapter 7 } // Supported by Mozilla
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Chapter 7 • All HTTP requests go
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8 AJAX Grid Data grids have always
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Chapter 8 Figure 8.2: AJAX Grid in
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$name = $_GET['name']; // update th
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} Chapter 8 if (!isset($_SESSION['r
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Chapter 8 # editId(, true) Edit
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Chapter 8 } // this should work for
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} Chapter 8 if(editableId) editId(e
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} color: darkblue; text-align: righ
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Chapter 8 On the client, this data
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Chapter 8 save() and undo() are hel
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9 AJAX RSS Reader In the last few y
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Chapter 9 Figure 9.1: Managing RSS
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header('Pragma: no-cache'); header(
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Chapter 9 Loading feed... Abou
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Chapter 9 } // continue if the proc
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Chapter 9 } width: 410px; backgroun
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And finally, we send the HTTP reque
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10 AJAX Drag and Drop When drag-and
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Chapter 10 The Prototype features a
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Chapter 10 When dropping a task on
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Chapter 10 DROP HERE TO DELETE
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header('Expires: Fri, 25 Dec 1980 0
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Chapter 10 } } } else if (action ==
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Chapter 10 11. Load http://localhos
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details are saved using a cache sys
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Chapter 10 Summary This is it! You'
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A Preparing Your Working Environmen
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Appendix A During installation you'
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Before going through any case studi
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Appendix A Preparing Your *nix Play
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8. Finally, point your web browser
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2. Write ajax in the Create a new d
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Index A abort() method, XMLHttpRequ
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exception handling, JavaScript, 43
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PHP Parameters and Error Handling r
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updateChart() function, realTimeCha
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