php 下拉菜单显示选中但默认为一个值

Question

我在 sql server 上使用 php 存储过程。我的问题是我想在下拉列表中默认显示一个值，但是当有人选择其他内容并刷新页面时，它必须显示该人选择的内容，而不是默认值。这是我到目前为止所做的：

<form method="post">
            <label for="from"><b>De:</b></label>
            <input  data-date-format='yy-mm-dd' type="text" id="from" name="from" size="6" value="<?php if(isset($_POST['from'])){ echo $_POST['from']; } ?>";/>
            <label for="to"><b>A:</b></label> 
            <input data-date-format='yyyy-mm-dd' type="text" id="to" name="to" size="6" value="<?php if(isset($_POST['to'])){ echo $_POST['to']; } ?>";/>
            <label for="group"><b>Groupe:</b></label> 
            <select type= "text" name="group" id="group" value="";>
            <option><?php if(isset($_POST['group'])){ echo $_POST['group']; } ?></option>
<?php
$sql = " Get_List_ReportStation";
$stmt = sqlsrv_query($conn, $sql);
if( $stmt === false) {
    die( print_r( sqlsrv_errors(), true) );}
while( $row = sqlsrv_fetch_array( $stmt, SQLSRV_FETCH_ASSOC) ) 
{ 
?>          
<option selected value="RAL"><?php echo ($row['F1000'] . " " . $row['F1018']); ?></option>       
<?php   
}
?>
</select>
<input type="submit" value="Valider" name="submit">
</form>
<?php 
if(isset($_POST["submit"])) {
$from = $_POST["from"];
$to = $_POST["to"];
$group = $_POST["group"];
}
?>

有什么想法可以帮助我吗？谢谢！

Answer 1

<select class="group">
    <option value="test1">test1</option>
    <option value="test2">test2</option>
    <option value="test3">test3</option>
    <option value="test4">test4</option>
</select>    

添加 Javascript 以将用户的最后一个值存储到本地存储中。

var select = document.querySelector(".group");
var selectOption = select.options[select.selectedIndex];
var lastSelected = localStorage.getItem('select');

if(lastSelected) {
    select.value = lastSelected; 
}

// sets up a onselected
select.onchange = function () {
   lastSelected = select.options[select.selectedIndex].value;
   console.log(lastSelected);
   localStorage.setItem('select', lastSelected);
}

来源：How to use LocalStorage on last HTML select value

对于你给定的代码试试这个

<form method="post">
            <label for="from"><b>De:</b></label>
            <input  data-date-format='yy-mm-dd' type="text" id="from" name="from" size="6" value="<?php if(isset($_POST['from'])){ echo $_POST['from']; } ?>";/>
            <label for="to"><b>A:</b></label> 
            <input data-date-format='yyyy-mm-dd' type="text" id="to" name="to" size="6" value="<?php if(isset($_POST['to'])){ echo $_POST['to']; } ?>";/>
            <label for="group"><b>Groupe:</b></label> 
            <select type= "text" name="group" id="group">
            <option><?php if(isset($_POST['group'])){ echo $_POST['group']; } ?></option>
<?php
$sql = " Get_List_ReportStation";
$stmt = sqlsrv_query($conn, $sql);
if( $stmt === false) {
    die( print_r( sqlsrv_errors(), true) );}
while( $row = sqlsrv_fetch_array( $stmt, SQLSRV_FETCH_ASSOC) ) 
{ 
?>          
<option value="<?php echo ($row['F1000']."_".$row['F1018']); ?>"><?php echo ($row['F1000'] . " " . $row['F1018']); ?></option>       
<?php   
}
?>
</select>
<input type="submit" value="Valider" name="submit">
</form>
<script>
var select = document.querySelector(".group");
var selectOption = select.options[select.selectedIndex];
var lastSelected = localStorage.getItem('select');

if(lastSelected) {
    select.value = lastSelected; 
} else {
    select.value = 'RAL'; // new code
}

// sets up a onselected
select.onchange = function () {
   lastSelected = select.options[select.selectedIndex].value;
   console.log(lastSelected);
   localStorage.setItem('select', lastSelected);
}
</script>
<?php 
if(isset($_POST["submit"])) {
$from = $_POST["from"];
$to = $_POST["to"];
$group = $_POST["group"];
}
?>