在打印方法中获取无线电值，以便将一些参数传输到另一个页面

Question

I have this code of PHP:

 <form action="modificaPriorita.php" method="post">
   <table>
     <tr id="format-tabelle">
        <th></th>
        <th><span class="format-celle">TITLE</span></th>
        <th><span class="format-celle">TYPE</span></th>
        </tr>
        <?php    
          $res = GestioneSegnalazione::showSegnalazioni();
          function drawTable($res) {
            $title = $res[0];
            $idAuthor = $res[1];
            $type = $res[2];

            for ($i = 0; $i < $num; $i++) {
               print "<tr class='row'>
               <td align='center' valign='middle'> <input type='radio' name='radio' value='$title[$i],$idAuthor[$i]'/> </td>
               <td align='center' valign='middle'><span class='format-celle'> $title[$i]</span></td>
               <td align='center' valign='middle'><span class='format-celle'> $type[$i]</span></td>
      ?>
     </table>
     <br>
     <input type="submit" name="show" value="Show" class='freshbutton-orange'  id='show-submit-segnalazione'/>
       <?
         if (isset($_POST['show'])) {
           if ($_POST[radio] == "") {
echo("<SCRIPT JavaScript'>window.alert('Select one segnalazione to show');window.location.href='showSegnalazione.php#close'</SCRIPT>");
           }
         }
 ?>

If i select one item in radio button and i press the button 'show' it works, it goes to the other page "modificaPriorita.php" with two parameters: title, idAuthor My problem is if i press the 'show' button without select one item in radio button, it would show me the error 'Select one segnalazione to show', but it goes to the new page ("modificaPriorita.php") without parameters. what can i do to have this error message?

Answer 1

You don't need to wait for your form to post before you can check to see if they selected a radio button. You can use javascript with the onsubmit listener like so:

<form action="modificaPriorita.php" method="post" onsubmit="return validateForm();">
    <table>
        <tr id="format-tabelle">
            <th></th>
            <th><span class="format-celle">TITLE</span></th>
            <th><span class="format-celle">TYPE</span></th>
        </tr>

<?php    
    $res = GestioneSegnalazione::showSegnalazioni();
    function drawTable($res) {
        $title = $res[0];
        $idAuthor = $res[1];
        $type = $res[2];

        for ($i = 0; $i < $num; $i++) {
            print "<tr class='row'>
                <td align='center' valign='middle'> <input type='radio' name='radio' value='$title[$i],$idAuthor[$i]'/> </td>
                <td align='center' valign='middle'><span class='format-celle'> $title[$i]</span></td>
                <td align='center' valign='middle'><span class='format-celle'> $type[$i]</span></td>
             </tr>";
       }
   }
?>
    </table>

    <br>

    <input type="submit" name="show" value="Show" class='freshbutton-orange'  id='show-submit-segnalazione'/>
</form>

<script>
    function validateForm() {
        var radios = document.getElementsByName('radio');

        var checked = false;

        for (var i = 0, length = radios.length; i < length; i++) {
            if (radios[i].checked) {
                checked = true;
                break;
            }
        }

        if (checked) {
            return true;            
        } else {
            alert('Select one segnalazione to show');
            return false;
        }
    }
</script>

So what happens in this code is right before the form gets submitted runs the validateForm() function we set up. In that function it checks to see if a radio button is selected. If it is then the function returns true which allows the form to post. If it doesn't find a radio button selected it does the alert window and then returns false which prevents the form from posting. I hope this helps.