send html select option disabled attribute with POST and enabled select option attribute with onclick in input form

Question

Hi i want send html select option disabled attribute with POST and enabled select option attribute with onclick in input form. For example i have:

<script>
function checked(){
     var sel = document.getElementById("table A");  
    if(sel.options[sel.selectedIndex].text=='AAAA'){
         document.getElementById('table B').disabled = false;
    }
}

</script>


<?php
        print("<form method=\"POST\">");
        <print("<tr><th>Table A</th><td>
        <select id='table A' name='table1'>
                <option value=' '>Select</option>
                <option name='AAAA' value='A' onclick=\"checked()\">AAAA</option>
                <option name='BBBB' value='B'>BBBB</option>
        </select></td></tr>");
     print("<tr><th>Table B</th><td>
        <select id='table B' name='table2' disabled>
                <option value=' '>Select</option>
                <option name='BBB' value='B'>BBBB</option>
                <option name='CCC' value='C'>CCCC</option>
                </select></td></tr>");
        print("<tr><td><input type=\"submit\" id=\"save\" name=\"save\" value=\"Save\" ></td></tr>");

if(isset($_POST['save'])){
if(document.getElementById("table B").disabled){
            return ' ';
            }else{
                $type_modify=$_POST['table B'];
                }
?>

Now if i I do not disable select form table B i want send with post ' '. If i click select option name='AAAA' i want enable select with id='table B'. My code doesn't work. why?

Answer 1

You can do it like this.

For example

<script>

function processForm(e) {
    if (e.preventDefault) e.preventDefault();

    var input = document.createElement('input');
    input.type = 'hidden';
    input.name = "my-disabled-check-input";
    input.value = document.getElementById('table B').disabled;
    this.appendChild(input);

    this.submit();
}

var form = document.getElementById('my-form');
if (form.attachEvent) {
    form.attachEvent("submit", processForm);
} else {
    form.addEventListener("submit", processForm);
}
</script>

You could also just add another onclick function as well without the same event listener and then submit the form with form.submit();

Then in your PHP file just treat it as a normal POST variable. You would want to look at $_POST['my-disabled-check-input']; if we are doing it like I setup.

In your form html you can set the POST URL. This URL can be the page that displays the form and also receive the POST variables. If you are unfamiliar with these terms then have a look at https://www.w3schools.com/html/html_forms.asp

But basically you can set an "action" which is just the URL to the php file.

So taken directly from W3schools a form looks like this.

<form action="/action_page.php">
  <label for="fname">First name:</label><br>
  <input type="text" id="fname" name="fname" value="John"><br>
  <label for="lname">Last name:</label><br>
  <input type="text" id="lname" name="lname" value="Doe"><br><br>
  <input type="submit" value="Submit">
</form>

If wanted to have a PHP file that displayed the form and took $_POST variables we can do something like this.

<?php
if($_POST) {
 echo "Post Variables sent";
 var_dump($_POST);
} else {
 echo "Where I will put my form HTML and JS.";
}
?>

Your PHP can also be used like this to make writing HTML easier.

<?php if($_POST): ?>
    Your name is <?=$_POST['fname']?> <?=$_POST['lname']?>.
<?php else: ?>
    <form action="/action_page.php">
      <label for="fname">First name:</label><br>
      <input type="text" id="fname" name="fname" value="John"><br>
      <label for="lname">Last name:</label><br>
      <input type="text" id="lname" name="lname" value="Doe"><br><br>
      <input type="submit" value="Submit">
    </form>
<?php endif; ?>

This <?=$_POST['fname']?> is equivalent to <?php echo $_POST['fname']; ?> but just a little shorter and I like using it that way in my HTML views.

This script doesn't take into consideration any user input parsing so keep that in mind. You may also want to look into HTML 5 form validation to make sure the input is only information you expect and also PHP filtering of user input.