89 lines
3.2 KiB
Markdown
89 lines
3.2 KiB
Markdown
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---
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title: PHP 5 Forms - Required Fields
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localeTitle: PHP 5表单 - 必填字段
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---
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本章介绍如何使输入字段成为必需，并在需要时创建错误消息。
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### PHP - 必填字段
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从上一页的验证规则表中，我们看到“名称”，“电子邮件”和“性别”字段是必需的。这些字段不能为空，必须在HTML表单中填写。
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|字段|验证规则| | --- | --- | |名称|必填。 +必须只包含字母和空格| |电子邮件|必填。 +必须包含有效的电子邮件地址（使用@和。）| |网站|可选。如果存在，则必须包含有效的URL | |评论|可选。多行输入字段（textarea）| |性别|必需。必须选择一个|
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在上一章中，所有输入字段都是可选的。
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在下面的代码中，我们添加了一些新变量：$ nameErr，$ emailErr，$ genderErr和$ websiteErr。这些错误变量将保存必填字段的错误消息。我们还为每个$ _POST变量_添加了if else语句_。这将检查$_ POST变量是否为空（使用PHP empty（）函数）。如果为空，则会在不同的错误变量中存储错误消息，如果它不为空，则通过test\_input（）函数发送用户输入数据：
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```php
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<?php
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// define variables and set to empty values
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$nameErr = $emailErr = $genderErr = $websiteErr = "";
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$name = $email = $gender = $comment = $website = "";
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if ($_SERVER["REQUEST_METHOD"] == "POST") {
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if (empty($_POST["name"])) {
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$nameErr = "Name is required";
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} else {
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$name = test_input($_POST["name"]);
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}
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if (empty($_POST["email"])) {
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$emailErr = "Email is required";
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} else {
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$email = test_input($_POST["email"]);
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}
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if (empty($_POST["website"])) {
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$website = "";
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} else {
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$website = test_input($_POST["website"]);
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}
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if (empty($_POST["comment"])) {
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$comment = "";
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} else {
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$comment = test_input($_POST["comment"]);
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}
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if (empty($_POST["gender"])) {
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$genderErr = "Gender is required";
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} else {
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$gender = test_input($_POST["gender"]);
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}
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}
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?>
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```
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### PHP - 显示错误消息
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然后在HTML表单中，我们在每个必填字段后添加一个小脚本，如果需要，会生成正确的错误消息（即如果用户尝试提交表单而不填写必填字段）：
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#### 例
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```php
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<form method="post" action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]);?>">
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Name: <input type="text" name="name">
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<span class="error">* <?php echo $nameErr;?></span>
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<br><br>
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E-mail:
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<input type="text" name="email">
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<span class="error">* <?php echo $emailErr;?></span>
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<br><br>
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Website:
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<input type="text" name="website">
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<span class="error"><?php echo $websiteErr;?></span>
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<br><br>
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Comment: <textarea name="comment" rows="5" cols="40"></textarea>
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<br><br>
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Gender:
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<input type="radio" name="gender" value="female">Female
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<input type="radio" name="gender" value="male">Male
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<span class="error">* <?php echo $genderErr;?></span>
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<br><br>
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<input type="submit" name="submit" value="Submit">
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</form>
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```
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下一步是验证输入数据，即“名称字段是否仅包含字母和空格？”和“电子邮件字段是否包含有效的电子邮件地址语法？”，如果填写完毕，“网站字段是否包含有效的URL？“
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