我正在创建一个内部网络工具，用于将数据插入数据库。我试图找出如何创建一个三层下拉列表选择，我将第三个下拉列表的值插入到数据库中。
我在这里偶然发现了这个答案：根据下拉列表选择从数据库填充另一个选择下拉列表
但是是作为两层下拉列表完成的。我的php代码是这样的：
<?php
require 'connect.php';
$query = "SELECT customer_id,customer FROM schema.customer";
$result = $DB_con->query($query);
while($row = $result->fetch(PDO::FETCH_ASSOC)){
$categories[] = array("customer_id" => $row['customer_id'], "customer" => $row['customer']);
}
$query = "SELECT contract_id, customer_id, contract FROM schema.contract";
$result = $DB_con->query($query);
while($row = $result->fetch(PDO::FETCH_ASSOC)){
$subcats[$row['customer_id']][] = array("contract_id" => $row['contract_id'], "contract" => $row['contract']);
}
// Third dropdown which isn't originally included with the previous answer
$query = "SELECT subcontract_id, contract_id, subcontract FROM schema.subcontract";
$result = $DB_con->query($query);
while($row = $result->fetch(PDO::FETCH_ASSOC)){
$subsubcats[$row['contract_id']][] = array("subcontract_id" => $row['subcontract_id'], "subcontract" => $row['subcontract']);
}
$jsonCats = json_encode($categories);
$jsonSubCats = json_encode($subcats);
$jsonSubSubCats = json_encode($subsubcats);
?>
现在，给出的答案是这样的：
<head>
<script type='text/javascript'>
<?php
echo "var categories = $jsonCats; 'n";
echo "var subcats = $jsonSubCats; 'n";
//Below wasn't part of the answer
echo "var subsubcats = $jsonSubSubCats; 'n";
?>
function loadCategories(){
var select = document.getElementById("categoriesSelect");
select.onchange = updateSubCats;
for(var i = 0; i < categories.length; i++){
select.options[i] = new Option(categories[i].customer,categories[i].customer_id);
}
}
function updateSubCats(){
var catSelect = this;
var customer_id = this.value;
var subcatSelect = document.getElementById("subcatsSelect");
subcatSelect.options.length = 0; //delete all options if any present
for(var i = 0; i < subcats[customer_id].length; i++){
subcatSelect.options[i] = new Option(subcats[customer_id][i].contract,subcats[customer_id][i].contract_id);
}
}
</script>
</head>
<body onload='loadCategories()'>
<select id='categoriesSelect'>
</select>
<select id='subcatsSelect'>
</select>
</body>
</html>
但是我需要基于第二个下拉选择的第三层选项的帮助。提前谢谢。:)
能够弄清楚。
<script type='text/javascript'>
<?php
echo "var categories = $jsonCats; 'n";
echo "var subcats = $jsonSubCats; 'n";
echo "var subsubcats = $jsonSubSubCats; 'n";
?>
function loadCategories(){
var select = document.getElementById("categoriesSelect");
select.onchange = updateSubCats;
for(var i = 0; i < categories.length; i++){
select.options[i] = new Option(categories[i].customer,categories[i].customer_id);
}
}
function updateSubCats(){
var customer_id = this.value;
var subcatSelect = document.getElementById("subcatsSelect")
subcatSelect.onchange = updateSubSubCats;;
for(var i = 0; i < subcats[customer_id].length; i++){
subcatSelect.options[i] = new Option(subcats[customer_id][i].contract,subcats[customer_id][i].contract_id);
}
}
function updateSubSubCats(){
var subsubcatSelect = this;
var contract_id = this.value;
var subsubcatSelect = document.getElementById("subsubcatsSelect");
subsubcatSelect.options.length = 0; //delete all options if any present
for(var i = 0; i < subsubcats[contract_id].length; i++){
subsubcatSelect.options[i] = new Option(subsubcats[contract_id][i].subcontract,subsubcats[contract_id][i].subcontract_id);
}
}
</script>