Ignoring initial loading of PHP_SELF - php

Question

I am learning PHP and I have a page that reloads back to itself. I want to know if you can ignore a certain function on the initial loading of the page and only call it once the form submit button has been clicked.
The page is passed a 'ticketID' and loads the information from it. I then want to be able to add a note using the following form method:
<form method="POST" action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]);?>">
<strong>Add Note:</strong>
<textarea name="note" rows="5" cols="40" value=><?php echo htmlspecialchars($note);?></textarea>
<span class="error">*<?php echo $noteErr;?></span><br>
The user then clicks on a submit button to submit the note for processing:
<button type='submit' name='ticketID' value= <?php echo $_POST['ticketID'];?> >View</button>
</form>
The 'ticketID' is then passed back to the page to reload the information.
If the submit button is pressed and no note has been entered I want a message box to display informing the user to include a note. I have tried:
if (!empty($_POST["note"]))
{
echo "This has updated...";
} else {
echo "Missing!";
}
However this loads the error message even on the initial load of the page. I have tried setting a variable to the POST ticketID value and clearing the POST value after the page has displayed and before testing for the error message:
$tempTicketID = $_POST['ticketID'];
$_POST['ticketID'] = NULL;
Then testing the error message, and finally setting the POS value back before the page ends to allow it to reload correctly again:
$_POST['ticketID'] = $tempTicketID;
However the POST value doesn't save and the page reloads with no information.
Any help would be great appreciated.
Here's the full code layout:
##LOAD THE PAGE INFO...
#Set the temp variable and clear the post value
$tempTicketID = $_POST['ticketID'];
$_POST['ticketID'] = NULL;
#Load the form
<form method="POST" action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]);?>">
<strong>Add Note:</strong>
<textarea name="note" rows="5" cols="40" value=><?php echo htmlspecialchars($note);?></textarea>
<span class="error">*<?php echo $noteErr;?></span><br>
<button type='submit' name='ticketID' value= <?php echo $_POST['ticketID'];?> >View</button>
</form>
#Test if the note is empty and the form button has been pressed
if (!empty($_POST["note"]))
{
echo "This has updated...";
} elseif (empty($_POST["ticketID"] {
echo "Missing!";
}
#Set POST value back to reload the page
$_POST['ticketID'] = $tempTicketID;

Answer 1

We need to restructure the form just a bit to make this happen. You can check if the form is submitted by testing for the button that must be clicked to submit. However, you're using that button for multiple purposes. To simplify, we'll have a separate submit button, and pass the ticketID value through the form with a hidden input. You shouldn't need the code that unsets the $_POST values.
<button type='submit' name='submit'> View</button>
<input type='hidden' name='ticketID' value= <?php echo $_POST['ticketID'];?> />
Then you can test if the form has been submitted with this quick check:
if (isset($_POST['submit'])) {
if (!empty($_POST["note"]))
{
echo "This has updated...";
} else {
echo "Missing!";
}
}