Getting data from the form in Java

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PHP includes a number of special built-in variables that give you access to loads of information Each of these variables is stored as an associative array (see 5 of this minibook for more on associative arrays) These

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special variables are available anywhere in your PHP code, so they re called superglobals Here s a few of the most important ones: $_GET: A list of variables sent to this program through the get method $_POST: A list of variables sent to this program through the post method $_REQUEST: A combination of $_GET and $_POST You can use these variables to look up information posted in the form For example, the askNamehtml page contains a field called userName When the user views this page, it sends a request to greetUserphp via the get method greetUserphp can then check its $_GET variable to see if a field named userName exists:

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$userName = $_GET[ userName ];

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This line checks all the data sent via get, looks for a field named userName, and copies the contents of that field to the variable $userName If you want to retrieve a value sent through the post method, use this variation:

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$userName = $_POST[ userName ];

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If you don t care whether the data was sent via get or post, use $_REQUEST:

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$userName = $_REQUES[ userName ];

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The $_REQUEST superglobal grabs data from both get and post requests, so it works, no matter how the form was encoded Many programmers use the $_REQUEST technique because then they don t have to worry about the encoding mechanism If you don t like the idea of somebody accessing your data without a form, use $_POST in your PHP program If data is encoded in the URL, your program ignores it because you re only responding to post data, and data encoded in the URL is (by definition) get data This solution is far from foolproof There s nothing to prevent a bad guy from writing his own form using the post method and passing data to your program that way You can never be 100-percent safe

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It s just as easy to get data from drop-down lists and radio buttons as it is to get data from text fields In PHP (unlike JavaScript), you use exactly the same technique to extract data from any type of form element

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Book V 3

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Can t I just have automatic access to form variables

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The earliest forms of PHP had a feature called register_globals which automatically did the $_REQUEST extraction for you If your program comes from a userName field, the program will magically just have a $userName variable pre-loaded with the value of that field While this was a very convenient option, evildoers soon learned how to take advantage of this behavior to cause all kinds of headaches Convenient as it may be, the register_globals feature is now turned off on most servers and isn t even available on the next version of PHP The $_REQUEST approach is safer and not much harder If you want even more control of how information is passed to your programs, investigate the filter functions that are in the latest versions of PHP They are not quite complete (as of this writing), but by the time PHP6 rolls around, they ll probably become an even better way to extract data from forms

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For an example of a more complex form, look over montyhtml in Figure 3-5 This program is a tribute to my favorite movie of all time (You might just have to rent this movie if you re really going to call yourself a programmer It s part of the culture)

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Figure 3-5: The Monty Python quiz features a drop-down list, radio buttons, and check boxes

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The XHTML form poses the questions (Check out Book I, 7 for a refresher on XHTML forms, if you need it) Here s the code:

<!DOCTYPE html PUBLIC -//W3C//DTD XHTML 10 Strict//EN http://wwww3org/TR/xhtml1/DTD/xhtml1-strictdtd > <html lang= EN dir= ltr xmlns= http://wwww3org/1999/xhtml > <head> <meta http-equiv= content-type content= text/xml; charset=utf-8 /> <title>montyhtml</title> <link rel = stylesheet type = text/css href = montycss /> </head> <body> <h1>Monty Python Quiz</h1> <form action = montyphp method = post > <fieldset> <p> <label>What is your name </label> <select name = name > <option value = Roger > Roger the Shrubber </option> <option value = Arthur > Arthur, King of the Britons </option> <option value = Tim > Tim the Enchanter </option> </select> </p> <p> <label>What is your quest </label> <span> <input type = radio name = quest value = herring /> To chop down the mightiest tree in the forest with a herring </span> <span> <input type = radio name = quest value = grail /> I seek the holy grail </span> <span> <input type = radio name = quest value = shrubbery /> I m looking for a shrubbery </span> </p> <p>

Getting data from the form in Java Generation PDF 417 in Java Getting data from the form

Getting data from the form in Java

Generation PDF 417 in Java Getting data from the form