使用爆炸性php编辑和更新复选框值

Question

如何修复问题通知：

未定义变量: C:\wamp64\www\MyFolder\version1.1\fms\build\english\equipment.php中的B行904 警告: C:\wamp64\www\MyFolder\version1.1\fms\build\english\equipment.php ()要求参数2为数组，在第904行的in_array中为null

<div class="form-group">
    <label class="custom-control custom-checkbox" style="margin-left: 10px; margin-right: 35px;">
        <input type="checkbox" name="equipment[]" value="Tv" class="custom-control-input" 
<?php 
if (isset($_POST["equipment_id"]))
    {
    $id = $_POST['equipment_id'];
    $query = mysqli_query("SELECT * FROM equipment WHERE id='$id'");
    $row = mysqli_fetch_array($query);
    $a = $row["equipment"];
    $b = explode(",", $a);
    print_r($b);
    }

if (in_array("Tv", $b))
    {
    echo "checked";
    }

?> >
        <span class="custom-control-indicator"></span>
        <img src="img/equipments/tv-icon.png" width="25px" height="25px">
        <span class="custom-control-description">TVs</span>
    </label>
    <label class="custom-control custom-checkbox" style="margin-right: 35px;">
        <input type="checkbox" name="equipment[]" value="Phone" class="custom-control-input">
        <span class="custom-control-indicator"></span>
        <img src="img/equipments/phone-icon.png" width="25px" height="25px">
        <span class="custom-control-description">Phone</span>
    </label>
    <label class="custom-control custom-checkbox" style="margin-right: 35px;">
        <input type="checkbox" name="equipment[]" value="Fan" class="custom-control-input">
        <span class="custom-control-indicator"></span>
        <img src="img/equipments/fan-icon.png" width="25px" height="25px">
        <span class="custom-control-description">Fan</span>
    </label>
    <label class="custom-control custom-checkbox" style="margin-right: 35px;">
        <input type="checkbox" name="equipment[]" value="Mirror" class="custom-control-input">
        <span class="custom-control-indicator"></span>
        <img src="img/equipments/mirror-icon.png" width="25px" height="25px">
        <span class="custom-control-description">Mirrors</span>
    </label>
</div>

Answer 1

根据我的注释，将in_array()条件放在isset()条件中。未定义变量的原因是$b只存在于isset()条件中。因此，当您离开isset()条件并尝试访问$b时，它会抛出错误

if (isset()){
#your isset() code

    if(in_array()){
#in_array() code

    } #place in_array() inside isset()
} # end isset()

作为一个提示，一定要养成在使用前定义变量的习惯。最后，请使用准备好的语句进行查询。

Answer 2

在php代码顶部，请声明数组$b

 $b=array();

在您的代码中，您将编写一个if条件，如果它不满足，那么$b变量是未定义的。因此，在条件之前，请声明数组如下。

$b=array();
if (isset($_POST["equipment_id"])) {
//your code        
}

谢谢