Required field will check whether the field is filled or not in the proper way. Most of cases we will use the
* symbol for required field.
What is Validation ?
Validation means check 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 sent to a server and perform validation checks in server machine.
Some of Validation rules for field
| Field |
Validation Rules |
| Name |
Should required letters and white-spaces |
| Email |
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
Below code shows 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 syntax will verify whether a given URL is valid or not. It should allow some keywords as https, ftp, www, a-z, 0-9,..etc..
Valid Email
Below code shows validation of Email address
$email = input($_POST["email"]);
if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
$emailErr = "Invalid format and please re-enter valid email";
}
Above syntax will verify whether given Email address is well-formed or not.if it is not, it will show an error message.
Example
Example below shows the form with 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 $data;
}
?>
<h2>Absolute classes registration</h2>
<p><span class = "error">* required field.</span></p>
<form method = "post" action = ">?php
echo htmlspecialchars($_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>
It will produce the following result −
thank you for nice information.
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