Form required fields
From the validation rules in the previous section, we see that the "Name", "E-mail" and "Gender" fields are required. These fields cannot be empty and must be filled in the HTML form.
Field Validation Rule
Name Required. Must contain letters and spaces.
E-mail required. Must contain a valid email address (including @ and .).
Website Optional. If optional, a valid URL must be included.
Comment Optional. Multi-line input field (text box).
Gender required. One must be selected.
In the previous section, all input fields were optional.
In the code below we have added some new variables: $nameErr, $emailErr, $genderErr and $websiteErr. These error variables hold the error message for the requested field. We also added an if else statement to each $_POST variable. This statement checks whether the $_POST variable is empty (via the PHP empty() function). If empty, the error message is stored in a different error variable. If not empty, the user input data is sent through the test_input() function:
<?php // 定义变量并设置为空值 $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 - Show error message
In the HTML form, we added a little script after each requested field. Appropriate error messages are generated if required (if the user attempts to submit the form without filling in required fields):
Example
<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>
<!DOCTYPE HTML> <html> <head> <style> .error {color: #FF0000;} </style> </head> <body> <?php // 定义变量并设置为空值 $nameErr = $emailErr = $genderErr = $websiteErr = ""; $name = $email = $gender = $comment = $website = ""; if ($_SERVER["REQUEST_METHOD"] == "POST") { if (empty($_POST["name"])) { $nameErr = "姓名是必填的"; } else { $name = test_input($_POST["name"]); } if (empty($_POST["email"])) { $emailErr = "电邮是必填的"; } 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 = "性别是必选的"; } else { $gender = test_input($_POST["gender"]); } } function test_input($data) { $data = trim($data); $data = stripslashes($data); $data = htmlspecialchars($data); return $data; } ?> <h2>PHP 验证实例</h2> <p><span class="error">* 必需的字段</span></p> <form method="post" action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]);?>"> 姓名:<input type="text" name="name"> <span class="error">* <?php echo $nameErr;?></span> <br><br> 电邮:<input type="text" name="email"> <span class="error">* <?php echo $emailErr;?></span> <br><br> 网址:<input type="text" name="website"> <span class="error"><?php echo $websiteErr;?></span> <br><br> 评论:<textarea name="comment" rows="5" cols="40"></textarea> <br><br> 性别: <input type="radio" name="gender" value="female">女性 <input type="radio" name="gender" value="male">男性 <span class="error">* <?php echo $genderErr;?></span> <br><br> <input type="submit" name="submit" value="提交"> </form> <?php echo "<h2>您的输入:</h2>"; echo $name; echo "<br>"; echo $email; echo "<br>"; echo $website; echo "<br>"; echo $comment; echo "<br>"; echo $gender; ?> </body> </html>
PHP Validation Example
* Required fields
Name: *
Email: *
Website:
Comments:
Gender: Female Male
Your input:

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