Display PHP Form Validation Results on Same Page

Question

I'm sure the initial reaction is going to be something like, "Doesn't this guy have Google?" Yes, I'll admit this does seem like a pretty basic concept and I've tried and tried to wrap my head around it, looked up all manner of posts and articles on the topic, etc., but all to no avail. Perhaps you can point me in the right direction?

I have a basic contact form (contact.html) that I run with an external PHP script (contact.php). Here's the HTML form code:

<form id="form1" action="contact.php" method="post">
<div class="form1">
<label>Your Name:</label>
<span><input type="text" name="name" /></span>
</div>
<div class="form1">
<label>Your School:</label>
<span><input type="text" name="school" /></span>
</div>
<div class="form1">
<label>Phone Number:</label>
<span><input type="text" name="phone" /></span>
</div>
<div class="form1">
<label>E-Mail Address:</label>
<span><input type="text" name="email" /></span>
</div>
<div class="form3">
<span><textarea cols="1" rows="1" name="message"></textarea></span>
</div>
<div class="wrapper">
<input class="submit" type="image" src="images/contact_submit.png" name="submit" alt="Submit" />
</div>
</form>

The PHP script validates that all of the fields were entered and then processes the form:

<?php

if ($_SERVER['REQUEST_METHOD'] == 'POST') {

//Validate the name:
if (!empty($_POST['name'])) {
    $name = $_POST['name'];
} else {
    echo "You forgot to enter your name.<br>";
}

//Validate the school:
if (!empty($_POST['school'])) {
    $school = $_POST['school'];
} else {
    echo "You forgot to enter your school.<br>";
}

//Validate the e-mail:
if (!empty($_POST['email'])) {
    $email = $_POST['email'];
} else {
    echo "You forgot to enter your e-mail.<br>";
}

//Validate the message:
if (!empty($_POST['message'])) {
    $message = $_POST['message'];
} else {
    echo "You forgot to enter a message.";
}

if (!empty($_POST['name']) && !empty($_POST['school']) && !empty($_POST['email']) && !empty($_POST['message'])) {
    $phone = $_POST['phone'];
    $body = "$name\n$school\n$phone\n$email\n\n$message";
    mail("***", "PAL Website - Message from a Visitor", $body);
    header("Location: confirm.html");
}

}

?>

Everything works great and the form is validated and processed as intended. However, I REALLY want to set it up so that the error messages are displayed on the same page or at least have the form refreshed with the error messages included.

I've seen this done in other demonstrations (Larry Ullman's book, for example), but still can't quite figure out how to make it happen. Can you please offer advice? What's the simplest way to go about it?

Here's the page URL, if it helps: http://www.712jefferson.org/pal/contact.html

Thank you!

Answer 1

There are many ways of doing this so this is a opinion based question which will get you several ways of accomplishing this.

You could do an ajax request to submit the data that way no reloading of the page and on the success of the call if any errors are in the response show the errors near the input that caused the error. This would require the use of javascript and setting a hidden element to the error and displaying it or generating the element containing the error and appending it to the DOM.

do as Amal Murali shows and put the html and validation script in the same script file and output the errors right away, or even better echo the errors near the inputs that caused them

yet another way would be to have contact.php do the validation and then on invalid data print out contact.html and again put the errors near the inputs.

Answer 2

code of index.php(This file is run first)

<?php
define('PROJECT',$_SERVER['DOCUMENT_ROOT'].'PhpSample');
include (PROJECT.'/utilities.php');
include ('constant.php');

if ($_SERVER["REQUEST_METHOD"] == "POST" && isset($_POST['submit'])) {

$errors = validate_errors($variables);
$counter = 0;
foreach ($errors as $value) {
    if ($value === '') {
        $counter++;
    }
}

//if there are no errors
if ($counter == 7) {
    //database operation
    $con = mysqli_connect($host, $user, $pword);
    if (!$con) {
        echo 'Error connecting to database. Please try again later';
        exit;
    }
    $val = cleanandinsert($variables,$con,$dbname);
    mysqli_close($con);
    if(!$val){
        echo 'Could not register. Please try again later';
        exit;
    }
    header("Location:http://localhost/PhpSample/target.php?vals=" .     urlencode(serialize($variables))); 
    exit;
  }
}


include('myform.phtml');
?>

Code of target.php

<?php
include 'process.php';
$Values= unserialize(urldecode($_GET['vals'])); 
echo "<h2>Your Input:</h2>";
echo "Firstname:".$Values['firstname'];
echo "<br>";
echo "Lastname:".$Values['lastname'] ;
echo '<br>';
echo "Username:".$Values['username'] ;
echo '<br>';
echo "Password:".$Values['password'] ; 
echo '<br>';
echo "Gender:".$Values['gender'] ;
echo '<br>';
if (!empty($Values['course'])) {
    $string = implode(',', $Values['course']);
} else {
    $string = "";
}
echo "Course(/s):" . $string;
echo '<br>';
echo "Comments:".$Values['comments'] ; 
echo '<br>';
?>

Code of constant.php

<?php
// define variables and set to empty values
$firstnameErr = $lastnameErr = $usernameErr = $passwordErr = $genderErr = $courseErr     = "";
$firstname = $lastname = $username = $password = $gender = $comments = "";
$course = array();
$variables = initialize();
$host = 'localhost';
$user = 'root';
$pword = '';
$dbname = 'mydb';
$tablename = 'userdata';
?>

Code of myform.phtml

<html>
<head>
    <title>Sample Form</title>
    <style>
        .error {color: #FF0000;}
    </style>
</head>
<body>
    <p><span class="error">* required field.</span></p>
    <form method="post" action="./index.php"> 
        <label for="firstname">Firstname:</label>                                                           
        <input type="text" name="firstname" id="firstname" value="<?php if (isset($variables['firstname']) ? print_r($variables['firstname']) : '') ; ?>" /><span class="error">* <?php if (isset($errors['firstname']) ? print_r($errors['firstname']) : '') ; ?></span><br/><br/>
        <label for="lastname">Lastname:</label>
        <input type="text" name="lastname" id="lastname" value="<?php if (isset($variables['lastname']) ? print_r($variables['lastname']) : '') ; ?>" /><span class="error"> <?php if (isset($errors['lastname']) ? print_r($errors['lastname']) : '') ; ?></span><br/><br/>
        <label for="username">Username:</label>
        <input type="text" name="username" id="username" value="<?php if (isset($variables['username']) ? print_r($variables['username']) : '') ; ?>" /><span class="error">* <?php if (isset($errors['username']) ? print_r($errors['username']) : '') ; ?></span><br/><br/>
        <label for="password">Password:</label>
        <input type="password" name="password" id="password" /><span class="error">* <?php if (isset($errors['password']) ? print_r($errors['password']) : '') ; ?></span><br/><br/>
        Gender:
        <label for="male">Male</label>
        <input type="radio" name="gender" id="male" <?php if (isset($variables['gender']) && ($variables['gender'] == "male")) echo "checked"; ?> value="male" />  
        <label for="female">Female</label>
        <input type="radio" name="gender" id="female" <?php if (isset($variables['gender']) && ($variables['gender'] == "female")) echo "checked"; ?> value="female" /><span class="error">* <?php if (isset($errors['gender']) ? print_r($errors['gender']) : '') ; ?></span><br/><br/>
        <label for="course">Course:</label>
        PHP<input type="checkbox" name="course[]" id="course" <?php echo getChecked("PHP") ?>  value="PHP" />
        HTML<input type="checkbox" name="course[]" id="course" <?php echo getChecked("HTML") ?> value="HTML" />
        CSS<input type="checkbox" name="course[]" id="course" <?php echo getChecked("CSS") ?> value="CSS" />
        Javascript<input type="checkbox" name="course[]" id="course" <?php echo getChecked("Javascript") ?> value="Javascript" /><span class="error">* <?php if (isset($errors['course']) ? print_r($errors['course']) : '') ; ?></span><br/><br/>
        <label for="comments">Comments:</label><br/>
        <textarea name="comments" rows="4" cols="20" id="comments"/><?php if (isset($variables['comments']) ? print_r($variables['comments']) : '') ; ?></textarea><br/><br/>
    <input type = "submit" value="Submit" name="submit">
</form>

Code of utilities.php

<?php

/** * It cleans the variable and returns variable free from cross site cripting. * @return variable free from whitespaces,stripped of slashes,tags. */

function clean($data, $ishtmltype = FALSE) {
if ($ishtmltype) {  //for database operation
    $data = htmlspecialchars(stripslashes(trim($data)));
    return $data;
}
$data = strip_tags(htmlspecialchars(stripslashes(trim($data))));

return $data;
}

/** * It returns an array of variables which are cleansed with the help of "clean()" * @return $var array */

  function initialize() {
   $var = array();
   $var['firstname'] = isset($_POST['firstname']) ? clean($_POST['firstname']) : '';
   $var['lastname'] = isset($_POST['lastname']) ? clean($_POST['lastname']) : '';
   $var['username'] = isset($_POST['username']) ? clean($_POST['username']) : '';
   $var['password'] = isset($_POST['password']) ? $_POST['password'] : '';
   if (!empty($_POST['gender'])) {                
    $var['gender'] = $_POST['gender'];
   } else {
    $var['gender'] = '';
  }
  //var_dump($_POST[gender]);
   if (!empty($_POST['course'])) {               
    $var['course'] = $_POST['course'];
   } else {
    $var['course'] = '';
   }
   $var['comments'] = isset($_POST['comments']) ? clean($_POST['comments']) : '';
    return $var;
   }

/** * It returns an array of error variables which have error messages in them * @param type $var array * @return $errors array */

function validate_errors($var) {    
$errors = array();

$errors['firstname'] = validateFirstName($var['firstname']); //should return error   string or ''
$errors['lastname'] = validateLastname($var['lastname']);
$errors['username'] = validateUserName($var['username']);
$errors['password'] = validatePassword($var['password']);
$errors['gender'] = validateGender($var['gender']);
$errors['course'] = validateCourse($var['course']);
$errors['comments'] = validateComments($var['comments']);
return $errors;
}

/** * It returns an error message, if any, in the first name * @param type $fname * @return string or null if not found */

function validateFirstName($fname) {

if (empty($fname)) {
    $firstnameErr = "First name is required";
    return $firstnameErr;
} else if (!preg_match("/^[a-zA-Z']*$/", $fname)) { // check if name only contains   letters and whitespace.Performs a regular expression match
    $firstnameErr = "Only letters are allowed";
    return $firstnameErr;
}
  else if (strlen($fname) < 3){
    $firstnameErr = "Atleast 3 characters";
    return $firstnameErr;
  }
   else if (strlen($fname) > 60){
    $firstnameErr = "Not more than 60 characters";
    return $firstnameErr;
  }
return '';
}

/** * It returns an error message, if any, in the last name * @param type $lname * @return string or null if not found */

function validateLastName($lname) {

if (empty($lname)) {
    return '';
} else if (!preg_match("/^[a-zA-Z ]*$/", $lname)) { // check if name only contains letters and whitespace,performs a regular expression match
    $lastnameErr = "Only letters are allowed";
    return $lastnameErr;
}
else if (strlen($lname) > 60){
    $firstnameErr = "Not more than 60 characters";
    return $firstnameErr;
  }
return '';
}

/** * It returns an error message, if any, in the user name * @param type $uname * @return string or null if not found */

function validateUserName($uname) {

if (empty($uname)) {
    $usernameErr = "Username is required";
    return $usernameErr;
} else if (!preg_match("/^[a-zA-Z0-9 ]*$/", $uname)) { // checks if username contains only letters and digits
    $usernameErr = "Only letters and digits are allowed";
    return $usernameErr;
}
else if (strlen($uname) < 3){
    $firstnameErr = "Atleast 3 characters";
    return $firstnameErr;
  }
   else if (strlen($uname) > 60){
    $firstnameErr = "Not more than 60 characters";
    return $firstnameErr;
  }
  return '';
}     

/** * It returns an error message, if any, in the password * @param type $pword * @return string or null if not found */

function validatePassword($pword) {

if (empty($pword)) {
    $passwordErr = "Password is required";
    return $passwordErr;
} else if (preg_match("/^.*(?=.{8,})(?=.*[0-9])(?=.*[a-z])(?=.*[A-Z]).*$/", $pword)     === 0) {
    $passwordErr = "Password must be at least 8 characters and must contain at least one lower case letter, one upper case letter and one digit";
    return $passwordErr;
}
return '';
}

/** * It returns an error message, if any, in the gender * @param type $gen * @return string or null if not found */

function validateGender($gen) {

if (empty($gen)) {
    $genderErr = "Gender is required";
    return $genderErr;
} else if (($gen != "male") && ($gen != "female")) {
    $genderErr = "Not a valid selection";
    return $genderErr;
}
return '';

}

/** * It returns an error message, if any, in the course * @param type $cour * @return string or null if not found */

function validateCourse($cour) {

if (empty($cour)) {
    $courseErr = "Select atleast one";
    return $courseErr;
} else if (array_values($cour) != ("PHP" && "HTML" && "CSS" && "Javascript")) {
    $courseErr = "Not a valid selection";
    return $courseErr;
}
return '';
}

/** * It doesnot return an error message, but accepts any content * @param type $comm * @return null */

function validateComments($comm) {

if (empty($comm)) {
    return '';
}
return '';
}

/** * It removes any special characters in a string and inserts the validated user data into the database * @param type $variables array * @param type $con * @param type $dbname * @return boolean */

function cleanandinsert($variables, $con, $dbname) {

$firstname = mysqli_real_escape_string($con, $variables['firstname']); //The mysqli_real_escape_string() function escapes special characters in a string for use in an SQL statement.
$lastname = mysqli_real_escape_string($con, $variables['lastname']);
$username = mysqli_real_escape_string($con, $variables['username']);
$password = sha1($variables['password']);    
$gender = mysqli_real_escape_string($con, $variables['gender']);
$string = implode(',', ($variables['course']));
$course = mysqli_real_escape_string($con, $string);
$comments = mysqli_real_escape_string($con, $variables['comments']);
$sql = "INSERT INTO $dbname.userdata (firstname,lastname,username,password,gender,course,comments)
                VALUES ('$firstname','$lastname','$username','$password','$gender','$course','$comments')";

if (!mysqli_query($con, $sql)) {

        return FALSE;        
}
return TRUE;
}

/** * It checks the checked checkboxes on the submission of the wrong data i.e it remembers the checked checkbox. * @param type $course * @return checked checkbox or null if a checkbox is not checked */

function getChecked($course){
if(!empty($_POST['course']) && in_array($course, $_POST["course"])){
    return 'checked';
}
return '';
}

?>

Answer 3

There are many ways for doing this, but the easy way to do this is "Put your Whole form code in php file and just make one file, i am not sure but it should work, the error will be shown below the form for that first write your form code and after write your php script".:)

Answer 4

I'd use jQuery for this. Modifications to be made:

in HTML: add id to your input fileds, so you can "grab" them with jQuery (You can see the usage in the $.post method below).

<form id="form1" action="contact.php" method="post">
   <div class="form1">
      <label>Your Name:</label>
      <span><input id="name" type="text" name="name" /></span>
   </div>
   <div class="form1">
      <label>Your School:</label>
      <span><input id="school" type="text" name="school" /></span>
   </div>
   <div class="form1">
      <label>Phone Number:</label>
      <span><input id="phone" type="text" name="phone" /></span>
   </div>
   <div class="form1">
      <label>E-Mail Address:</label>
      <span><input id="email" type="text" name="email" /></span>
   </div>
   <div class="form3">
      <span><textarea id="message" cols="1" rows="1" name="message"></textarea></span>
   </div>
   <div class="wrapper">
      <input class="submit" type="image" src="images/contact_submit.png" name="submit" alt="Submit" />
   </div>
</form>

in PHP: if there is no error in validation echo this: "success"

if (!empty($_POST['name']) && !empty($_POST['school']) && !empty($_POST['email']) && !empty($_POST['message'])) {
    echo "success";
    $phone = $_POST['phone'];
    $body = "$name\n$school\n$phone\n$email\n\n$message";
    mail("***", "PAL Website - Message from a Visitor", $body);
    header("Location: confirm.html");
}

Attach jQuery library to your site and use the code below in your HTML file inside brackets or in an external *.js file attached to Your site. In Your HTML file's section use this:

<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js">
</script>

jQuery script:

$('#form1').submit(function() {
    event.preventDefault(); 
    $.post("contact.php", {name: $("#name").val(), school: $("#school").val(), phone: $("#phone").val(), email: $("#email").val(), message: $("#message").val()}, function(data){
        if(data !="success"){
            alert(data);
        }
    });
});

This will give Your error messages in a alert window and Your site won't reload if I'm not mistaken.

Answer 5

    <?php
    // define variables and set to empty values
    $firstnameErr = $lastnameErr = $usernameErr = $passwordErr = $genderErr = $courseErr = "";
    $firstname = $lastname = $username = $password = $gender = $comments = "";
    $course = array();
    //var_dump($_POST['gender']);
    //exit;
    if ($_SERVER["REQUEST_METHOD"] == "POST" && isset($_POST['submit'])) {

    $variables = array();
    $variables = initialize();
    $errors = array();
    $errors = validate_errors($variables);

    if (count($errors) == 0) {
        //database operation
        //exit;
    }
    }  
    function clean($data) {
    $data = strip_tags(htmlspecialchars(stripslashes(trim($data)))); 
     //trim :- Strip whitespace (or other characters) from the beginning and end of a string
     //The stripslashes() function removes backslashes.Prevents XSS
     //htmlspecialchars :- Converts the predefined characters "<" (less than) and ">" (greater than) to HTML entities:< (less than) becomes &lt; and > (greater than) becomes &gt;Helps in preventing XSS
     //The strip_tags() function strips a string from HTML, XML, and PHP tags.
    return $data;
    }

    function initialize(){
    $var = array();
    $var['firstname'] = clean($_POST['firstname']);
    $var['lastname'] = clean($_POST['lastname']);
    $var['username'] = clean($_POST['username']);
    $var['password'] = clean($_POST['password']);
    if(!empty($_POST['gender'])) {                //if-else condition is used because here we don't type in any data,but just select data
    $var['gender'] = $_POST['gender'];
    }  else {
        $var['gender'] = '';
    }
    //var_dump($_POST[gender]);
    if(!empty($_POST['course'])) {               //if-else condition is used because here we don't type in any data,but just select data
    $var['course'] = $_POST['course'];
    } else {
        $var['course'] = '';
    }
    $var['comments'] = clean($_POST['comments']);
    return $var;
     }

    function validate_errors($var) {    //is an array being passed into this function??have a look at arg of validateFirstName.
    $errors = array();

    $errors['firstname'] = validateFirstName($var['firstname']);//should return error string or ''
    $errors['lastname'] = validateLastname($var['lastname']);
    $errors['username'] = validateUserName($var['username']);
    $errors['password'] = validatePassword($var['password']);
    $errors['gender'] = validateGender($var['gender']);
    $errors['course'] = validateCourse($var['course']);
    $errors['comments'] = validateComments($var['comments']);
    return $errors;
   }

      function validateFirstName($fname){

      if(empty($fname)){
        global $firstnameErr;
        $firstnameErr = "First name is required";
        return $firstnameErr;
    } else if (!preg_match("/^[a-zA-Z ]*$/", $fname)){ // check if name only contains letters and whitespace.Performs a regular expression match
        global $firstnameErr;
        $firstnameErr = "Only letters are allowed";
        return $firstnameErr;
    } else {
        global $firstname;
       $firstname = $fname;
       return ''; 
    }   
}    

function validateLastName($lname){

    if(empty($lname)){
        return '';
    } else if (!preg_match("/^[a-zA-Z ]*$/", $lname)) { // check if name only contains letters and whitespace,performs a regular expression match
        global $lastnameErr;
        $lastnameErr = "Only letters are allowed";
         return $lastnameErr;
    } else {
        global $lastname;
        $lastname = $lname;
       return ''; 
    }
}

function validateUserName($uname) {

    if(empty($uname)) {
        global $usernameErr;
        $usernameErr = "Username is required";
        return $usernameErr;
    } else if (!preg_match("/^[a-zA-Z0-9 ]*$/", $uname)){ // checks if username contains only letters and digits
        global $usernameErr;
        $usernameErr = "Only letters and digits are allowed";
        return $usernameErr;
    } else {
        global $username;
        $username = $uname;
       return ''; 
    }  
}

function validatePassword($pword){

    if(empty($pword)) {
        global $passwordErr;
        $passwordErr = "Password is required";
        return $passwordErr;
    } else if (preg_match("/^.*(?=.{8,})(?=.*[0-9])(?=.*[a-z])(?=.*[A-Z]).*$/", $pword) === 0) {
        global $passwordErr;
        $passwordErr = "Password must be at least 8 characters and must contain at least one lower case letter, one upper case letter and one digit";
        return $passwordErr;
    } else {
        global $password;
        $password = $pword;
       return '';  
    }
}    

function validateGender($gen){

    if(empty($gen)) {
        global $genderErr;
        $genderErr = "Gender is required";  
      return $genderErr;
    } else {
        global $gender;
        $gender = $gen;
        return '';
    }
}

function validateCourse($cour){

    if(empty($cour)) {
        global $courseErr;
        $courseErr = "Select atleast one";
        return $courseErr;
    } else {
        global $course;
        $course = $cour;
        return '';
    }
}

function validateComments($comm){

    if(empty($comm)) {
        return '';
    } else {
        global $comments;
        $comments = $comm;
        return '';
    }
}


    //renderform();



    ?>


    <html>
    <head>
        <title>Sample Form</title>
        <style>
            .error {color: #FF0000;}
        </style>
    </head>
    <body>
        <p><span class="error">* required field.</span></p>
        <form method="post" action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]); ?>"> 
            <label for="firstname">Firstname:</label>
            <input type="text" name="firstname" id="firstname" value="<?php echo $firstname; ?>" /><span class="error">* <?php echo $firstnameErr; ?></span><br/><br/>
            <label for="lastname">Lastname:</label>
            <input type="text" name="lastname" id="lastname" value="<?php echo $lastname; ?>" /><span class="error"> <?php echo $lastnameErr; ?></span><br/><br/>
            <label for="username">Username:</label>
            <input type="text" name="username" id="username" value="<?php echo $username; ?>" /><span class="error">* <?php echo $usernameErr; ?></span><br/><br/>
            <label for="password">Password:</label>
            <input type="password" name="password" id="password" /><span class="error">* <?php echo $passwordErr; ?></span><br/><br/>
            Gender:
            <label for="male">Male</label>
            <input type="radio" name="gender" id="male" <?php if (isset($gender) && $gender == "male") echo "checked"; ?> value="male" />  
            <label for="female">Female</label>
            <input type="radio" name="gender" id="female" <?php if (isset($gender) && $gender == "female") echo "checked"; ?> value="female" /><span class="error">* <?php echo $genderErr; ?></span><br/><br/>
            <label for="course">Course:</label>
            PHP<input type="checkbox" name="course[]" id="course" <?php if((!empty($_POST["course"])&& in_array("PHP",$_POST["course"]))){echo "checked";}?> value="PHP" />
            HTML<input type="checkbox" name="course[]" id="course" <?php if((!empty($_POST["course"])&& in_array("HTML",$_POST["course"]))){echo "checked";}?> value="HTML" />
            CSS<input type="checkbox" name="course[]" id="course" <?php if((!empty($_POST["course"])&& in_array("CSS",$_POST["course"]))){echo "checked";}?> value="CSS" />
            Javascript<input type="checkbox" name="course[]" id="course" <?php if((!empty($_POST["course"])&& in_array("Javascript",$_POST["course"]))){echo "checked";}?> value="Javascript" /><span class="error">* <?php echo $courseErr; ?></span><br/><br/>
            <label for="comments">Comments:</label><br/>
            <textarea name="comments" rows="4" cols="20" id="comments"/><?php echo $comments; ?></textarea><br/><br/>
        <input type = "submit" value="Submit" name="submit">
    </form>
     <?php
    echo "<h2>Your Input:</h2>";
    echo "Firstname:" . $firstname;
    echo "<br>";
    echo "Lastname:" . $lastname;
    echo '<br>';
    echo "Username:" . $username;
    echo '<br>';
    echo "Password:" . $password;
    echo '<br>';
    echo "Gender:" . $gender;
    echo '<br>';
    global $string;
    $string = implode(",",$course);
    echo "Course(/s):" . $string;
    echo '<br>';
    echo "Comments:" . $comments;
    echo '<br>';
    ?>
    </body>
    </html>

Answer 6

You can use ladder if..else structure for your code in if() you will put your condition and if the condition is false it will go to the error message and then you can put link of the main form, so that the user can go back...