如何从$_POST数组的下拉列表中识别所选值 - How do I identify the selected value from a dropdown list in the $_POST array?

How do I identify the selected value from a dropdown list in the $_POST array?

本文关键字：下拉列表识别数组 POST | 更新日期: 2023-09-27

我在html中有一个下拉列表<select>列表。用户提交表单后，如何识别$_POST数组中的选定值？

    <form action="subj_exec.php">
        <?php
        echo $_SESSION['SESS_MEMBER_ID'];
        echo $_SESSION['SESS_FIRST_NAME'];
        echo $_SESSION['SESS_LAST_NAME'];
        ?>
        <br>
        <select name = "subj_id">
            <?php
            while ($row = mysqli_fetch_array($result)) {
                $subject_id = $row['id'];
                $code = $row['code'];
                $name = $row['name'];
                echo '<option value=';
                echo $subject_id;
                echo '> ';
                echo $name;
                echo '</option>';
            }
            ?>
        </select>
        <input type="submit" value="submit" name="submit" />
    </form>

subject_id在另一个php文件中为空

echo $_POST['subject_id']为空。

请帮助识别代码中的问题。

谢谢，

表单的标准方法是GET，因此需要将method="POST"添加到表单中。

get：默认值。以名称/值对将表单数据追加到URL：URL？name=值&name=值

post：将表单数据作为HTTP后事务发送

<form action="subj_exec.php" method="POST">  //<<<< added method
<?php
echo $_SESSION['SESS_MEMBER_ID'];
echo $_SESSION['SESS_FIRST_NAME'];
echo $_SESSION['SESS_LAST_NAME'];
?>
<br>
<select name = "subj_id">
    <?php
    while ($row = mysqli_fetch_array($result)) {
        $subject_id = $row['id'];
        $code = $row['code'];
        $name = $row['name'];
        ?>
        <option value="<?= $subject_id; ?>"><?= $name; ?></option>
        <?php
    }
    ?>
</select>
<input type="submit" value="submit" name="submit" />

在您的文件subj_exec.php中，您可以使用输出选定的值

echo $_POST['subj_id'];

开始：

index.php

<form action="subj_exec.php" method="POST">
<?php
    echo $_SESSION['SESS_MEMBER_ID'];
    echo $_SESSION['SESS_FIRST_NAME'];
    echo $_SESSION['SESS_LAST_NAME'];
?>
<select name="subj_id">
    <?php
        while ($row = mysqli_fetch_array($result)) {
            $subject_id = $row['id'];
            $code = $row['code'];
            $name = $row['name'];
            echo '<option value="'.$subject_id.'">'.$name.'</option>';
        }
    ?>
</select>
<input type="submit" value="submit" name="submit" />

subj_exec.php

<?php
error_reporting(E_ALL ^ E_NOTICE);
if(isset($_POST['submit'])) {
    if(strlen($_POST['subj_id']) >= 1) {
        $option = htmlentities($_POST['subj_id'], ENT_QUOTES, "UTF-8");     
        // Do Something here with $option
        echo $option;
    }else {
        echo 'nothing selected.';
    }
}
?>