how to validate one variable either of two variables in php - php

Question

i have two variables mobile and email now i want to validate both but i want the user to leave blank one of the fields if user does not have one for ex if a user does not want to register with his email then he can go to mobile number for registration and vice versa this is my validation code
<?php
$emailError = "";
$fullnameError = "";
$usernameError = "";
$passwordError = "";
$mobileerror = "";
$errors = 0;
if ((isset($_POST['submit']))) {
$email = strip_tags($_POST['email']);
$fullname = strip_tags($_POST['fullname']);
$username = strip_tags($_POST['username']);
$password = strip_tags($_POST['password']);
$mobile = strip_tags($_POST['mobile']);
$fullname_valid = $email_valid = $mobile_valid = $username_valid = $password_valid = false;
if (!empty($fullname)) {
if (strlen($fullname) > 2 && strlen($fullname) <= 30) {
if (!preg_match('/[^a-zA-Z\s]/', $fullname)) {
$fullname_valid = true;
# code...
} else {
$fullnameError = "fullname can contain only alphabets <br>";
$errors++;
}
} else {
$fullnameError = "fullname must be 2 to 30 char long <br>";
$errors++;
}
} else {
$fullnameError = "fullname can not be blank <br>";
$errors++;
}
if (filter_var($email, FILTER_VALIDATE_EMAIL)) {
$query2 = "SELECT email FROM users WHERE email = '$email'";
$fire2 = mysqli_query($con, $query2) or die("can not fire query" . mysqli_error($con));
if (mysqli_num_rows($fire2) > 0) {
$emailError = $email . "is already taken please try another one<br> ";
} else {
$email_valid = true;
}
# code...
} else {
$emailError = $email . "is an invalid email address <br> ";
$errors++;
}
# code...
if ($mobile) {
$query4 = "SELECT mobile FROM users WHERE mobile = '$mobile'";
$fire4 = mysqli_query($con, $query4) or die("can not fire query" . mysqli_error($con));
if (mysqli_num_rows($fire4) > 0) {
$mobileerror = "is already taken please try another one<br> ";
} else {
$mobile_valid = true;
}
}
if (!empty($username)) {
if (strlen($username) > 4 && strlen($username) <= 15) {
if (!preg_match('/[^a-zA-Z\d_.]/', $username)) {
$query = "SELECT username FROM users WHERE username = '$username'";
$fire = mysqli_query($con, $query) or die("can not fire query" . mysqli_error($con));
if (mysqli_num_rows($fire) > 0) {
$usernameError = '<p style="color:#cc0000;">username already taken</p>';
$errors++;
} else {
$username_valid = true;
}
} else {
$usernameError = "username can contain only alphabets <br>";
$errors++;
}
} else {
$usernameError = "username must be 4 to 15 char long <br>";
$errors++;
}
} else {
$usernameError = "username can not be blank <br>";
$errors++;
}
if (!empty($password)) {
if (strlen($password) >= 5 && strlen($password) <= 15) {
$password_valid = true;
$password = md5($password);
# code...
} else {
$passwordError = $password . "password must be between 5 to 15 character long<br>";
$errors++;
}
# code...
} else {
$passwordError = "password can not be blank <br>";
$errors++;
}
//if there's no errors insert into database
if ($errors <= 0) {
if ($fullname_valid && ($email_valid || $mobile_valid )&& $password_valid && $username_valid) {
$query = "INSERT INTO users(fullname,email,username,password,avatar_path) VALUES('$fullname','$email','$username','$password','avatar.jpg')";
$fire = mysqli_query($con, $query) or die("can not insert data into database" . mysqli_error($con));
if ($fire) {
header("Location: dashboard.php");
}
}
}
}
?>
now when i use email and leave blank mobile the code works fine but when i use email and leave blank mobile then error occurs how to solve this problem

Answer 1

Use one more flag
$isValid_email_mobile = FALSE;
When control flow enters into if (filter_var($email, FILTER_VALIDATE_EMAIL)) then on SUCCESS just set $isValid_email_mobile = TRUE; It will be same if control enters in condition if ($mobile) again on SUCCESS , set it as $isValid_email_mobile = TRUE;
When $isValid_email_mobile = FALSE; becomes TRUE then you know that of the field/variable has passed your requirement and its ready for DB INSERT
Then
In your last IF condition when you try to INSERT just change IF condition to the following
IF ($fullname_valid && $isValid_email_mobile && $password_valid && $username_valid)
One more thing whenever you are using Flag logic always set your flag to some default value before using it.

Answer 2

now when i use email and leave blank mobile the code works fine but when i use email and leave blank mobile then error occurs
you have:
if (!empty($fullname)) {}
if (filter_var($email, FILTER_VALIDATE_EMAIL)) {}
if ($mobile) {}
if (!empty($username)) {}
if (!empty($password)) {}
To remove the error, try adding
if (!empty($mobile)) {
Also, I would suggest to wrap the statements a bit more. You only need one to fail in order to stop input. You could do something like this:
$mobileOrEmail = false;
if (!empty($fullname) && !empty($username) && !empty($password) {
//check fullname, username and password
if (!empty($mobile) {
//check mobile, if it passes
$mobileOrEmail = true;
}
if (filter_var($email, FILTER_VALIDATE_EMAIL)) {
//check email, if it passes
$mobileOrEmail = true;
}
if (!$mobileOrEmail) $errors++;
} else {
//missing input values
$errors++;
}
Personally, I would create a function for each input field.
function checkUsername($username){
//check username
return true;
}
function checkEmail($email) {
//check email
return true;
}
....
then you can run
if (checkUsername($username) && checkPassword($password)
&& checkFullname($fullname) && (checkEmail($email) || checkEmail($email)) {
//user input correct
} else {
//user input failed
}
Just to give it more structure