How to use PHP for form validation? - php

Question

Well, I have the following problem: my little test website is near completion and all that’s left is PHP validation on submit. But there exactly lies my problem. I can’t seem to let it validate when the user clicks submit.
I searched plenty of websites but on all of those they submit the page to the same page, and I submit the page to a new page. I don’t know how different this is from the first method but I can’t seem to get it to work.
I have 5 fields in my form which need to be required:
<table>
<tr>
<td align="right">Naam:</td>
<td align="left"><input type="text" name="naam" onkeydown="return names(event)"/></td>
</tr>
<tr>
<td align="right">Woonplaats:</td>
<td align="left"><input type="text" name="woonplaats" onkeydown="return names(event)"/></td>
</tr>
<tr>
<td align="right">Straatnaam:</td>
<td align="left"><input type="text" name="straatnaam" onkeydown="return names(event)"/></td>
</tr>
<tr>
<td align="right">Huisnummer:</td>
<td align="left"><input type="text" class="formnumbers" name="huisnummer"/></td>
</tr>
<tr>
<td align="right">Telefoonnummer:</td>
<td align="left"><input type="text" name="telefoonnummer" onkeydown="return phonenumber(event)"/></td>
</tr>
</table>
That’s all. My form action is as follows:
<form action="?page=pizza_bestelling" method="post" name="orderform">
I know PHP validation should be really easy (at least that’s what I’ve heard) but I can’t seem to work it out myself, so that’s why I decided to ask it here.
Now all it needs to do is check if one of those 5 fields is empty, if so don’t submit. Otherwise submit.
(Keep in mind that I have 16 fields in my form, it counts only for these 5 specific, the other 11 can be empty)
I appreciate any help in this matter, since it’s all that’s left before completing my website!
Thanks in advance!

Answer 1

Upon submiting you will lose "?page=pizza_bestelling" of the link, you can set it in a hidden input with that value if you need it passed.
set the method to method="post" in the form
and on the same page you will need something like
function validate_form($data)
{
//rules that will end with return false; if they are not valid
// example
if (!isset($data["naam"]) || $data["naam"] == '') return false; // if the name is not set or it's empty
// return true if all validation checks are passed
return true;
}
if ($_SERVER["REQUEST_METHOD"] === "POST")
{
$form_data['naam'] = $_POST['naam'];
$form_data['woonplaats'] = $_POST['woonplaats'];
// and so forth for each variable
// run the validate_form function for the data you got through POST
validate_form($form_data);
}else
{
//form displayed here
}

Answer 2

You want to set up an errors array which will store any errors, and allow you to print them out if necessary.
Then you check each variable in the following manner:
$errors = array(); //initialise error array
if (empty($_POST['naam'])) {
$errors[] = 'You forgot to add a name';
} else {
$name = trim($_POST['naam']);
}
This checks if the naam input and writes a message to the errors array if it's empty, or assigns the value to the $name variable if not.
Once you've gone through all your inputs, you can then perform a check on the errors array:
if (empty($errors)) { // If everything's OK.
//do what you need to do
} else {
echo '<p>The following errors occurred:<br/>';
foreach ($errors as $msg) {
echo "$msg<br/>\n";
}
echo '<p>Please try again</p>';
}
This only checks for empty fields of course - you should implement more validation for valid emails etc. For useability purposes you should really look at a one-page solution with sticky fields though.

Answer 3

Do a for each as follows:
$allowed = array("naam","woonplaats","stratnaam","formnumbers","telefoonnummer");
foreach ($allowed as $key => $val){
if($_POST[$key] == "")
$errors = true;
}
if($errors){
// don't submit
}
else {
// submit
}