How to stop user from entering only space in input PHP? - php

Question

I am creating a social site and in the registration code someone can enter only spaces in the input fields.
I don't want them to enter any spaces in the fields except for the password one.
I have tried a bunch of things, empty, trim, htmlentities !trim and some more I forgot. None of them worked. Some of them gave the first name the value of 1.
What am I missing?
Below is a list of things I have tried (not at the same time).
$first_name = trim(strip_tags(filter_var($_POST['first_name'], FILTER_SANITIZE_STRING)));
str_replace(' ', ' ', $first_name);
if (empty($first_name)) {
echo "Fill in first name to sign up";
}
if (!ctype_alnum($first_name)) {
echo "Invalid first name, it only may contain letters or digits";
}
$first_name = $_POST['first_name'] ?? '';
if (empty($first_name)) {
echo "Fill in first name to sign up";
}
if (!ctype_alnum($first_name)) {
echo "Invalid first name, it only may contain letters or digits";
}
$first_name = htmlentities(trim(strip_tags(filter_var($_POST['first_name'], FILTER_SANITIZE_STRING)));
if (empty($first_name)) {
echo "Fill in first name to sign up";
}
if (!ctype_alnum($first_name)) {
echo "Invalid first name, it only may contain letters or digits";
}

Answer 1

Use regular expressions. The following checks it to be at least 5 symbols and contain just letters and digits;
$firstName = trim($_POST['first_name']);
if (!preg_match("/^[a-zA-Z0-9]{5,}$/", $firstName)){
echo 'Invalid';
}
More information on preg_match() can be found here.

Answer 2

Hey i have simple solution regarding your question try one
If you want to submit only text and whitespace than use this one
<input type="text" name="Name" required pattern="[a-zA-Z ]+" >
If you want to submit number and whitespace than use this one
<input type="text" name="Name" required pattern="[0-9 ]+" >
If you want to insert text not whitespace than use this one
<input type="text" name="Name" required pattern="[a-zA-Z]+" >
Use any line according to your requirements no extra line of code or condition simple and secure