php - 如何在php mysql中显示依赖于下拉子类别的父类别

Question

我正在尝试显示用户从下拉列表中选择的子类别并显示他的父类别，但是我的代码显示显示直到二级父类别我在 php 中是新的，请帮助我，谢谢

显示所有类别

    <?php 

$result = mysqli_query($mysqli, "SELECT category.*, cat.name as parentName FROM category left join category as cat on category.parentId = cat.id  ORDER BY id ASC"); // using mysqli_query instead

    while($res = mysqli_fetch_array($result)) {         
        echo "<tr>";
         echo "<td>".$res['id']."</td>";
        echo "<td>".$res['name']."</td>";
        echo "<td>".$res['description']."</td>";

        echo "<td>".$res['parentId']."</td>"; 
        echo "<td>".$res['parentName']."</td>"; 

        echo "<td><a href=\"update.php?id=$res[id]&parentId=$res[parentId]\">Edit</a> | <a href=\"action/delete.php?id=$res[id]\" onClick=\"return confirm('Are you sure you want to delete?')\">Delete</a></td>";        
    }
    ?>

我得到 parentid 和 id 并将其发送到更新页面，

更新类别.php

        <form action="action/update-category.php" method="post" class="form-horizontal">
    <fieldset>
    <?php 
    include_once './action/connection.php'; 
    ?>
    <?php
    $id = $_GET['id']; // 
    $parentId = $_GET['parentId'];
    $sql  = "SELECT * FROM category WHERE id = $id";

    $result = mysqli_query($mysqli, $sql);
    $mainCategories = array();
    if (mysqli_num_rows($result) > 0) {
        // output data of each row
        while($row = mysqli_fetch_assoc($result)) {
            $mainCategories[] = $row;
        }
    } else {
        echo "0 results";
    }
    // echo "<b>Thank you! Record UPDATED Successfully!";
      ?>
    <!-- Form Name -->
    <legend>Edit Product</legend>
    <div class="col-md-12">
        <div class="form-group" id="category_main">
          <label class="col-md-6 control-label" for="product_categorie">CATEGORY</label>
          <div class="col-md-6">
          <select for="category_main" onchange="loadChildCategories(this);" id="" name="mainCategory_1" class="form-control category_main">
            <option> Please select parent category</option>
            <?php
        foreach ($mainCategories AS $eachCategory) {
        echo "<option value='".$eachCategory['parentId']."'>".$eachCategory['name']."</option>";
                }

            ?>
             </select>
          </div>
        </div>
    </div>

通过 Id 更新类别

    <?php


include_once 'connection.php';
if(!empty($_POST["parentId"])) {
$id = $_POST['parentId'];
$sql  = "SELECT * FROM category WHERE id='".$id."' Or parentId = '0'";
$result = mysqli_query($mysqli, $sql);
$childCategories = array();
$response = array();
if (mysqli_num_rows($result) > 0) {
    $response['hasChildCategories'] = true;
    $htmlChildCategories = '<div class="form-group" id="category_'.$id.'">
      <label class="col-md-6 control-label" for="product_categorie">CATEGORY</label>
      <div class="col-md-6">
      <select for="category_'.$id.'" onchange="loadChildCategories(this)" name="mainCategory_'.$id.'" class="form-control category_main">
        <option value="'.$id.'"> Select parent category</option>';

    // output data of each rowa
    while($row = mysqli_fetch_assoc($result)) {
        $childCategories[] = $row;
        $htmlChildCategories .= '<option value="'.$row['id'].'">'.$row['name'].'</option>';
    }
    $htmlChildCategories .= '</select></div></div>';
    $response['html'] = $htmlChildCategories;
}
else
{
    $response['hasChildCategories'] = false;
    $response['html'] = '';
}

echo json_encode($response);

}
?>

已满 full code

Answer 1

实际上问题出在您的 Update-category.php 代码中，您在其中仅选择了所选类别的父类别。您必须编写递归函数来获取以上所有父类别。

如果您提供了 loadChildCategories() 的定义，那么很容易回答您。但您仍然可以查看以下 URL，它会对您有所帮助。

How can I recursively get the IDs of all the parent elements in a multidimensional array?

谢谢