PHP Form - Required Fields

In PHP, there are fields that cannot be empty and must be filled out in html forms.

In this section we'll show you how to set up the form required fields and error messages.

PHP - Required field

In the previous section we covered the validation rules for the table, and we can see that the "Name", "E-mail", and "Gender" fields are required and each field cannot be empty.

Field Verification rule
Name Required.+ Only only letters and spaces
E-mail Required.+ Requirements contain a valid email address (including "@" and ".")
Website Optional.If there is, it must contain a valid URL
Comment Optional.Multi-line fields (text domain).
Gender Required.Must Select One

If in the previous section, all input fields are optional.

We've added some new variables to the following code: $nameErr, $emailErr, $genderErr, and $websiteErr. T hese error variables appear on the required fields. W e also added _POST if else statement for each $variable. T hese statements check whether the $_POST variable is empty (empty() function using php). I f empty, the corresponding error message is displayed. If it is not empty, the data is passed to test_input() function: 

<?php                
// 定义变量并默认设为空值                
$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"]);}                
                
  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"]);}                
}                
?>

PHP - Displays an error message

In the HTML instance form below, we've added some scripts to each field that display error messages when the information is entered incorrectly. (If the user submits the form without filling out the information, the error message is output):

<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>
<label>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>

Run an instance . . .