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Form Validation Using PHP
about 9 years ago
What is form Validation ?
This is the process to validate web form according to our data format, when the user try to submit wrong data in the field, server will not submit wrong data because we have restricted(validate) the all field according to our required data format. The validation can be done in PHP where developers set some rules. For example: If the name field is blank, then the code will take the user back to the form and display an error message.HTML Form : This the HTML form, I have used in this form four field text box, radio button, textarea and Submit button. Please check below code.
<html> <h2> PHP Form Validation Example </h2> <p><span class="error">* required field.</span></p> Name: <input type="text" name="name"> <br><br> E-mail: <input type="text" name="email"> <br><br> Website: <input type="text" name="website"> <br><br> Comment: <textarea name="comment" rows="5" cols="40"></textarea> <br><br> Gender: <input type="radio" name="gender" value="female">Female <input type="radio" name="gender" value="male">Male <span class="error">* <br><br> <input type="submit" name="submit" value="Submit"> </form> </body> </html></center>After implementing above code look like this.
<<!DOCTYPE HTML> <html> <head> <style> .error {color: #FF2300;}// this the error message color code </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"]); // check if name only contains letters and whitespace if (!preg_match("/^[a-zA-Z ]*$/",$name)) { $nameErr = "Only letters and white space allowed"; } }
if (empty($_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"]); // check if URL address syntax is valid if (!preg_match("/\b(?:(?:https?|ftp):\/\/|www.)[-a-z0-9+&@#\/%?=~_|!:,.;]*[-a-z0-9+&@#\/%=~_|]/i",$website)) { $websiteErr = "Invalid URL"; } }
if (empty($_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 $data; } ?>
<h2>PHP Form Validation Example</h2> <p><span class="error">* required field.</span></p> <form method="post" action="<?php echo htmlspecialchars($_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> Website: <input type="text" name="website"> <span class="error"><?php echo $websiteErr;?></span> <br><br> Comment: <textarea name="comment" rows="5" cols="40"></textarea> <br><br> Gender: <input type="radio" name="gender" value="female">Female <input type="radio" name="gender" value="male">Male <span class="error">* <?php echo $genderErr;?></span> <br><br> <input type="submit" name="submit" value="Submit"> </form>
<?php echo "<h2>Your Input:</h2>"; echo $name; echo "<br>"; echo $email; echo "<br>"; echo $website; echo "<br>"; echo $comment; echo "<br>"; echo $gender; ?>
</body> </html>
Alos you can learn my previous blog "How to insert data Value from an HTML form into MySQL Databse. After reading blog you can easily understand how to insert value in the database.
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