Hello folks! welcome back to a new edition of our tutorial on PHP. In this tutorial guide, we are going to be studying about the PHP Form Validation.
What is a Required Field?
A required field checks if the field is filled or not in the proper manner. In most cases we use the asterisk (*) symbol for the required field.
What is Form Validation?
Form validation is the process of checking the input submitted by the user. There are two types of validations made available in PHP. They are as follows -
- Client-side Validation - This type of validation is carried out on the client browser.
- Server-side Validation - This type of validation is carried out on the PHP server.
READ: PHP Form Handling
Validation Rules for Field
Following below are some of the validation rules for field in PhP -
| Field | Validation Rules |
|---|---|
| Name | Should required letters and white-spaces |
| Should required @ and . | |
| Website | Should required a valid URL |
| Radio | Must be selectable at least once |
| Check Box | Must be checkable at least once |
| Drop Down menu | Must be selectable at least once |
Valid URL
The following code below illustrates the validation of URL -
$website = input($_POST["site"]); if (!preg_match("/\b(?:(?:https?|ftp):\/\/|www\.)[-a-z0-9+&@#\/%?=~_|!:,.;]*[-a-z0-9+&@#\/%=~_|]/i",$website)) { $websiteErr = "Invalid URL"; }
Above code verifies if a given URL is valid or not. It should allow some keywords as https, www, ftp, a-z, 0-9, and so on.
Valid Email
The following code below illustrates the validation of Email address -
$email = input($_POST["email"]); if (!filter_var($email, FILTER_VALIDATE_EMAIL)) { $emailErr = "Invalid format and please re-enter valid email"; }
The above code will verify if a given Email address is well formatted or not. If it is not, then it is going to display an error message.
READ: PHP for Perl Developers
Example
Following example displays the PHP form with the required field validation -
<html> <head> <style> .error {color: #FF0000;} </style> </head> <body> <?php // define variables and set to empty values $nameErr = $emailErr = $genderErr = $websiteErr = ""; $name = $email = $gender = $comment = $website = ""; if ($_SERVER["REQUEST_METHOD"] == "POST") { if (empty($_POST["name"])) { $nameErr = "Name is required"; }else { $name = test_input($_POST["name"]); } if (empty($_POST["email"])) { $emailErr = "Email is required"; }else { $email = test_input($_POST["email"]); // check if e-mail address is well-formed if (!filter_var($email, FILTER_VALIDATE_EMAIL)) { $emailErr = "Invalid email format"; } } if (empty($_POST["website"])) { $website = ""; }else { $website = test_input($_POST["website"]); } if (empty($_POST["comment"])) { $comment = ""; }else { $comment = test_input($_POST["comment"]); } if (empty($_POST["gender"])) { $genderErr = "Gender is required"; }else { $gender = test_input($_POST["gender"]); } } function test_input($data) { $data = trim($data); $data = stripslashes($data); $data = htmlspecialchars($data); return $data; } ?> <h2>Web Design Tutorialz course registration form</h2> <p><span class = "error">* required field.</span></p> <form method = "post" action = "<?php echo htmlspecialchars($_SERVER["PHP_SELF"]);?>"> <table> <tr> <td>Name:</td> <td><input type = "text" name = "name"> <span class = "error">* <?php echo $nameErr;?></span> </td> </tr> <tr> <td>E-mail: </td> <td><input type = "text" name = "email"> <span class = "error">* <?php echo $emailErr;?></span> </td> </tr> <tr> <td>Time:</td> <td> <input type = "text" name = "website"> <span class = "error"><?php echo $websiteErr;?></span> </td> </tr> <tr> <td>Classes:</td> <td> <textarea name = "comment" rows = "5" cols = "40"></textarea></td> </tr> <tr> <td>Gender:</td> <td> <input type = "radio" name = "gender" value = "female">Female <input type = "radio" name = "gender" value = "male">Male <span class = "error">* <?php echo $genderErr;?></span> </td> </tr> <td> <input type = "submit" name = "submit" value = "Submit"> </td> </table> </form> <?php echo "<h2>Your given values are as:</h2>"; echo $name; echo "<br>"; echo $email; echo "<br>"; echo $website; echo "<br>"; echo $comment; echo "<br>"; echo $gender; ?> </body> </html>
Output
When the above code is executed, it will produce the following result -
Alright guys! This is where we are rounding up for this tutorial post. In our next tutorial guide, we are going to be discussing about PHP Complete Form.
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