How to validate form field in php - php

Question

I have a registration form that has some required field. i want to check if those required fields are filled and if they are filled correctly before i insert in my database.
One of the required field is email, i also want to check if the email entered is a valid email.
My code is below.
Thanks in advance for your help, i really appreciate it.
<?php
include 'config.php';
$tbl_name="citizens"; // Table name
// Get values from form and formatting them as SQL strings
$firstname = mysql_real_escape_string($_POST['firstname']);
$middlename = mysql_real_escape_string($_POST['middlename']);
$lastname = mysql_real_escape_string($_POST['lastname']);
$sex = mysql_real_escape_string($_POST['sex']);
$address = mysql_real_escape_string($_POST['address']);
$employer = mysql_real_escape_string($_POST['employer']);
$posincom = mysql_real_escape_string($_POST['posincom']);
$states = mysql_real_escape_string($_POST['states']);
$agerange = mysql_real_escape_string($_POST['agerange']);
$income = mysql_real_escape_string($_POST['income']);
$email = mysql_real_escape_string($_POST['email']);
$phone = mysql_real_escape_string($_POST['phone']);
// Insert data into mysql
$sql="INSERT INTO `$tbl_name` (firstname, middlename, lastname, sex, address, employer, position_in_company, states, age_range, local_govt_area, email, phone) VALUES('$firstname', '$middlename', '$lastname', '$sex', '$address', '$employer', '$posincom', '$states', '$agerange', '$income', '$email', '$phone')";
$result=mysql_query($sql);
// if successfully insert data into database, displays message "Successful".
if($result){
echo "You Have Successful Registered";
}else {
echo "Sorry!!! Could Not Register You. All a* fields must be field.";
}
?>

Answer 1

<?php
include 'config.php';
$tbl_name="citizens"; // Table name
$required = array('email');
$errors = array();
foreach($required as $required_fieldname){
if(!isset($_POST[$required_fieldname]) || empty($_POST[$required_fieldname])){
$errors[] = 'Sorry!!! Could Not Register You. All a* fields must be field.';
break;
}
}
if(isset($_POST['email']) && !filter_var($_POST['email'], FILTER_VALIDATE_EMAIL)){
$errors[] = "That is not a valid email address.";
}
if(count($errors) == 0){
// Get values from form and formatting them as SQL strings
$firstname = mysql_real_escape_string($_POST['firstname']);
$middlename = mysql_real_escape_string($_POST['middlename']);
$lastname = mysql_real_escape_string($_POST['lastname']);
$sex = mysql_real_escape_string($_POST['sex']);
$address = mysql_real_escape_string($_POST['address']);
$employer = mysql_real_escape_string($_POST['employer']);
$posincom = mysql_real_escape_string($_POST['posincom']);
$states = mysql_real_escape_string($_POST['states']);
$agerange = mysql_real_escape_string($_POST['agerange']);
$income = mysql_real_escape_string($_POST['income']);
$email = mysql_real_escape_string($_POST['email']);
$phone = mysql_real_escape_string($_POST['phone']);
// Insert data into mysql
$sql="INSERT INTO `$tbl_name` (firstname, middlename, lastname, sex, address, employer, position_in_company, states, age_range, local_govt_area, email, phone) VALUES('$firstname', '$middlename', '$lastname', '$sex', '$address', '$employer', '$posincom', '$states', '$agerange', '$income', '$email', '$phone')";
$result= mysql_query($sql);
// if successfully insert data into database, displays message "Successful".
if($result){
echo "You Have Successfully Registered";
}else {
echo "A technical error has occured.";
}
}
else{
echo '<strong>ERRORS!</strong><br>';
foreach($errors as $error){
echo $error . '<br>';
}
}
?>

Answer 2

you should validate form before submitting at client side using JavaScript, and alert to user if not filled correctly. Once validated allow it to submit .
In other case it is overhead to validate at server and than again send response to user at client end.

Answer 3

<?php
include 'config.php';
$tbl_name="citizens"; // Table name
// Get values from form and formatting them as SQL strings
//your other fields ...
$email = mysql_real_escape_string($_POST['email']);
if(!filter_var($email, FILTER_VALIDATE_EMAIL)){
$errors = 1;
echo "Please enter a correct email address";
}
//similar approach can be used for other fields..
// this is one of the simplest validating approach
if($errors == 0){
// Insert data into mysql
$sql="INSERT INTO `$tbl_name` (firstname, middlename, lastname, sex, address, employer, position_in_company, states, age_range, local_govt_area, email, phone) VALUES('$firstname', '$middlename', '$lastname', '$sex', '$address', '$employer', '$posincom', '$states', '$agerange', '$income', '$email', '$phone')";
$result=mysql_query($sql);
// if successfully insert data into database, displays message "Successful".
if($result){
echo "You Have Successful Registered";
}else {
echo "Sorry!!! Could Not Register You. All a* fields must be field.";
}
}
?>

Answer 4

For email you can use this (or similar) functions from https://stackoverflow.com/questions/3314493/check-for-valid-email-address to validate email
function isValidEmail($email){
return preg_match("^[_a-z0-9-]+(\.[_a-z0-9-]+)*#[a-z0-9-]+(\.[a-z0-9-]+)*(\.[a-z]{2,3})$^", $email);
}
Or
function isValidEmail( $email ){
return filter_var( $email, FILTER_VALIDATE_EMAIL );
}
For the rest, you can use the following
<?php
$error = '';
//put chosen function here
function isValidEmail( $email ){
return filter_var( $email, FILTER_VALIDATE_EMAIL );
}
//get values and validate each one as required
$firstname = mysql_real_escape_string($_POST['firstname']);
if(!$firstname){ $error .= "First name is required<br />"; }
//repeat for each field
$email = mysql_real_escape_string($_POST['email']);
if(!isValidEmail($email)){ $error .= "The email entered is invalid<br />"; }
//and so on...
if(!$error){
//add insert into database code here
}
else{
//display $error however you want e.g....
echo "<div class=\"error\">$error</div>";
}
?>

Answer 5

1.) you can use PHP_FILTER for validation.
2.) you can proper check( variable is null or not) before insert the data if variable is null the display error msg otherwish insert..