form validation in php and mysql | Vkprogramming

An HTML form contains various input fields such as text box, checkbox, radio buttons, submit button, and checklist, etc. These input fields need to be validated, which ensures that the user has entered information in all the required fields and also validates that the information provided by the user is valid and correct.

 

There is no guarantee that the information provided by the user is always correct. PHP

validates the data at the server-side, which is submitted by HTML form

. You need to validate a few things:

  1. Empty String
  2. Validate String
  3. Validate Numbers
  4. Validate Email
  5. Validate URL
  6. Input length

 

What is Validation?

Validation means checking the input submitted by the user. There are two types of validation are available in PHP. They are as follows −

 

  • Client-Side Validation − Validation is performed on the client machine web browsers.
  • Server-Side Validation − After submitted by data, The data has been sent to a server and performed validation checks in the server machine.

 

Empty String

The code below checks that the field is not empty. If the user leaves the required field empty, it will show an error message. Put these lines of code to validate the required field.

if (emptyempty ($_POST[“name”])) {

$errMsg = “Error! You didn’t enter the Name.”;

echo $errMsg;

} else {

$name = $_POST[“name”]; }

Validate String

The code below checks that the field will contain only alphabets and whitespace, for example – name. If the name field does not receive valid input from the user, then it will show an error message:

$name = $_POST [“Name”];

if (!preg_match (“/^[a-zA-z]*$/”, $name) ) {

$ErrMsg = “Only alphabets and whitespace are allowed.”;

echo $ErrMsg;

} else {

echo $name; }

 

Validate Number

The below code validates that the field will only contain a numeric value. For example – Mobile no. If the Mobile no field does not receive numeric data from the user, the code will display an error message:

 

$mobileno = $_POST [“Mobile_no”];

if (!preg_match (“/^[0-9]*$/”, $mobileno) ){

$ErrMsg = “Only numeric value is allowed.”;

echo $Errsg;

} else {

echo $mobileno;

}

 

Validate Email

A valid email must contain @ and. symbols. PHP provides various methods to validate the email address. Here, we will use regular expressions to validate the email address.

The below code validates the email address provided by the user through HTML form. If the field does not contain a valid email address, then the code will display an error message:

 

$email = $_POST [“Email”];

$pattern = “^[_a-z0-9-]+(.[_a-z0-9-]+)*@[a-z0-9-]+(.[a-z0-9-]+)*(.[a-z]{2,3})$^”;

if (!preg_match ($pattern, $email) ){

$ErrMsg = “Email is not valid.”;

echo $ErrMsg;

} else {

echo “Your valid email address is: ” .$email; }

 

Input Length Validation

The input length validation restricts the user to provide the value between the specified range, for Example – Mobile Number. A valid mobile number must have 10 digits.

The given code will help you to apply the length validation on user input:

 

$mobileno = strlen ($_POST [“Mobile”]);

$length = strlen ($mobileno);

if ( $length < 10 && $length > 10) {

$ErrMsg = “Mobile must have 10 digits.”;

echo $ErrMsg;

} else {

echo “Your Mobile number is: ” .$mobileno; }

 

Validate URL

The below code validates the URL

of website provided by the user via HTML form. If the field does not contain a valid URL, the code will display an error message, i.e., “URL is not valid”.

$websiteURL = $_POST[“website”];

if (!preg_match(“/b(?:(?:https?|ftp)://|www.)[-a-z0-9+&@#/%?=~_|!:,.;]*[-a-z0-9+&@#/%=~_|]/i”,$website)) {

 

$websiteErr = “URL is not valid”;

echo $websiteErr;

} else {

echo “Website URL is: ” .$websiteURL;

}

 

Button Click Validate

The below code validates that the user click on submit button and send the form data to the server one of the following method – get or post.

 

if (isset ($_POST[‘submit’]) {

echo “Submit button is clicked.”;

if ($_SERVER[“REQUEST_METHOD”] == “POST”) {

echo “Data is sent using POST method “;

}

} else {

echo “Data is not submitted”;

}

 

Note: Remember that validation and verification are different from each other.

Now we will apply all these validations to an HTML form to validate the fields. Thereby you can learn in detail how these codes will be used to validate a form.

 

Create and validate a Registration form

<!DOCTYPE html> 

<html> 

<head> 

<style> 

.error {color: #FF0001;} 

</style> 

</head> 

<body>   

$nameErr = $emailErr = $mobilenoErr = $genderErr = $websiteErr = $agreeErr = “”; 

$name = $email = $mobileno = $gender = $website = $agree = “”; 

//Input fields validation 

if ($_SERVER[“REQUEST_METHOD”] == “POST”) { 

//String Validation 

    if (emptyempty($_POST[“name”])) { 

         $nameErr = “Name is required”; 

    } else { 

        $name = input_data($_POST[“name”]); 

            // check if name only contains letters and whitespace 

            if (!preg_match(“/^[a-zA-Z ]*$/”,$name)) { 

                $nameErr = “Only alphabets and white space are allowed”; 

            }    } 

    //Email Validation  

    if (emptyempty($_POST[“email”])) { 

            $emailErr = “Email is required”; 

    } else { 

            $email = input_data($_POST[“email”]); 

            // check that the e-mail address is well-formed 

            if (!filter_var($email, FILTER_VALIDATE_EMAIL)) { 

                $emailErr = “Invalid email format”;             }      } 

    //Number Validation 

    if (emptyempty($_POST[“mobileno”])) { 

            $mobilenoErr = “Mobile no is required”; 

    } else { 

     $mobileno = input_data($_POST[“mobileno”]); 

            // check if mobile no is well-formed 

            if (!preg_match (“/^[0-9]*$/”, $mobileno) ) { 

            $mobilenoErr = “Only numeric value is allowed.”; 

            } 

        //check mobile no length should not be less and greator than 10 

        if (strlen ($mobileno) != 10) { 

            $mobilenoErr = “Mobile no must contain 10 digits.”; 

            }     } 

     //URL Validation     

    if (emptyempty($_POST[“website”])) { 

        $website = “”; 

    } else { 

            $website = input_data($_POST[“website”]); 

            // check if URL address syntax is valid 

            if (!preg_match(“/b(?:(?:https?|ftp)://|www.)[-a-z0-9+&@#/%?=~_|!:,.;]*[-a-z0-9+&@#/%=~_|]/i”,$website)) { 

                $websiteErr = “Invalid URL”; 

            }        }

    //Empty Field Validation 

    if (emptyempty ($_POST[“gender”])) { 

            $genderErr = “Gender is required”; 

    } else { 

            $gender = input_data($_POST[“gender”]);     } 

    //Checkbox Validation 

    if (!isset($_POST[‘agree’])){ 

            $agreeErr = “Accept terms of services before submit.”; 

    } else { 

            $agree = input_data($_POST[“agree”]); 

    } } 

function input_data($data) { 

  $data = trim($data); 

  $data = stripslashes($data); 

  $data = htmlspecialchars($data); 

  return $data; 

 

<h2>Registration Form</h2>

<span class = “error”>* required field </span>

<br><br>

<form method=”post” action=”<?php echo htmlspecialchars($_SERVER[“PHP_SELF”]); ?>” >

Name:

<input type=”text” name=”name”>

<span class=”error”>* <?php echo $nameErr; ?> </span>

<br><br>

E-mail:

<input type=”text” name=”email”>

<span class=”error”>* <?php echo $emailErr; ?> </span>

<br><br>

Mobile No:

<input type=”text” name=”mobileno”>

<span class=”error”>* <?php echo $mobilenoErr; ?> </span>

<br><br>

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    Website:  

<input type=”text” name=”website”>

<span class=”error”><?php echo $websiteErr; ?> </span>

<br><br>

Gender:

<input type=”radio” name=”gender” value=”male”> Male

<input type=”radio” name=”gender” value=”female”> Female

<input type=”radio” name=”gender” value=”other”> Other

<span class=”error”>* <?php echo $genderErr; ?> </span>

<br><br>

Agree to Terms of Service:

<input type=”checkbox” name=”agree”>

<span class=”error”>* <?php echo $agreeErr; ?> </span>

<br><br>

<input type=”submit” name=”submit” value=”Submit”>

<br><br>

</form>

if(isset($_POST[‘submit’])) {

if($nameErr == “” && $emailErr == “” && $mobilenoErr == “” && $genderErr == “” && $websiteErr == “” && $agreeErr == “”) {

echo “<h3 color = #FF0001> <b>You have sucessfully registered.</b> </h3>”;

echo “<h2>Your Input:</h2>”;

echo “Name: ” .$name;

echo “<br>”;

echo “Email: ” .$email;

echo “<br>”;

echo “Mobile No: ” .$mobileno;

echo “<br>”;

echo “Website: ” .$website;

echo “<br>”;

echo “Gender: ” .$gender;

} else {

echo “<h3> <b>You didn’t filled up the form correctly.</b> </h3>”;     }   }

</body>

</html>

hen the above code runs on a browser, the output will be like the screenshot below:

Fill the registration form and click on the Submit button. If all required information is provided correctly, the output will be displayed on the same page below the submit button. See the screenshot below:

form validation in php and mysql | Vkprogramming

Some of the Validation rules for field

form validation in php and mysql

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