loading edit form only if GET var exists in database

Question

What my script currently does:

• grabs & cleans a $_GET['id']
• pulls all pre-existing data from TABLE for that id
• displays form populated with any pre-existing data
• SUBMIT sends form data to update script, adds all data to TABLE

What I want my script to do:

• grabs & cleans a $_GET['id']
• pulls all possible (id)'s from TABLE (this I know how to do)
• checks that $_GET['id'] is in array ID (this I know how to do)
• IF NOT, kill script, do not display form, and echo error message (this I don't)
• IF YES, proceed as normal
• pulls all pre-existing data from TABLE for that id
• displays form populated with any pre-existing data
• SUBMIT sends form data to update script, adds all data to TABLE

Current script structure:

• php code
• html form with <?php _ ?> inserts for all values

I've tried to be a good lad and separate my code, and have largely succeeded. But that's left me with the problem that my html form displays whether the $_GET['id'] is legit or not.

Could someone please help me set it up so that if (!in_array($id, $allIDs)) prevents the form from displaying and tosses out an error instead?

Other than making the form an echoed HEREDOC, is there a way to control the display of that html?

Psuedocode is acceptable. I didn't bother posting my actual code because I didn't think the problem really merited such specificity. I can if need be...

Answer 1

pulls all possible (id)'s from TABLE, checks that $_GET['id'] is in array ID (this I know how to do)

That's stupidly inefficient. You should ask the DB if it has a row with ID = $_GET['id'].

I'd show you how to do that if you show how you're currently doing DB queries.

Other than making the form an echoed HEREDOC, is there a way to control the display of that html?

Well, this works, maybe surprisingly:

<?php
if ($should_show_form) {
?>
<form action="">
  <input type="submit">
</form>
<?php
} else {
    //do something else
}
?>