Saturday, October 31, 2009

Creating Listboxes








Creating Listboxes


Unlike the HTML controls we've already seen, HTML listboxes, created with <SELECT> controls, can support multiple selections. For example, take a look at phplistbox.html, Example 5-9, where we're letting the user select his or her favorite fruits.


Example 5-9. Listboxes, phplistbox.html



<HTML>
    <HEAD>
        <TITLE>Using Lists</TITLE>
    </HEAD>

    <BODY>
        <CENTER>
            <H1>Using Lists</H1>
            <FORM METHOD="GET" ACTION="listbox.php">
                Select your favorite fruit(s):
                <BR>
                <BR>
                <SELECT NAME="Food[]" MULTIPLE="TRUE">
                    <OPTION>Apple</OPTION>
                    <OPTION>Orange</OPTION>
                    <OPTION>Pear</OPTION>
                    <OPTION>Pomegranate</OPTION>
                </SELECT>
                <BR>
                <BR>
                <INPUT TYPE="SUBMIT" VALUE="Submit">
            </FORM>
        </CENTER>
    </BODY>
</HTML>



The user can select multiple listbox items, as you see in Figure 5-9.


Figure 5-9. Using listboxes.

[View full size image]



We've named the listbox "Food" here, but because multiple selections are possible, we can't just recover the selections using $_REQUEST["Food"]. Instead, we can refer to the first selection, if there is one, as $_REQUEST["Food"][0], the second, if there is one, as $_REQUEST["Food"][1], and so on. To catch them all, we'll use a foreach loop as you see in listbox.php, Example 5-10.


Example 5-10. Retrieving data from lists, listbox.php



<HTML>
    <HEAD>
        <TITLE>Using Lists</TITLE>
    </HEAD>

    <BODY>
        <CENTER>
            <H1>Retrieving Data From Lists</H1>
            You selected:
            <BR>
            <?php
            foreach($_REQUEST["Food"] as $fruit){
                echo $fruit, "<BR>";
            }
            ?>
        </CENTER>
    </BODY>
</HTML>



The results appear in Figure 5-10, where, as you can see, we're retrieving the selections the user made in a multi-user listbox. Not bad.


Figure 5-10. Reading data from listboxes.

[View full size image]









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