如果“选择”验证失败，则回传数据

Question

提交选定选项后，数据不会被存储。 只是想知道如何验证失败后回发数据

以下行不真的为我工作。

<select id="numbers" name="numbers" value="<?php echo (isset($_POST['numbers'])) ? $_POST['numbers'] : " "; ?>"/> 

如果有人能给我一只手？

非常感谢，这是我的代码

<?php 

if(isset($_POST['numbers']) &&($_POST['fruits']) && $_POST['numbers'] != "null" && $_POST['fruits'] !== "null") 
{ 
    echo "Thank you!"; 
} elseif (isset($_POST['numbers']) && $_POST['numbers'] = "null") { 
    echo "you forgot to choose a number"; 
    } 
    elseif(isset($_POST['fruits']) && $_POST['fruits'] = "null") 
{ 
    echo "you forgot to choose fruit name"; 
    } 

?> 



    <form id="form" name="form" method="post" action=""> 

     <label for="expiry">Select</label> 
       <select id="numbers" name="numbers" value="<?php echo (isset($_POST['numbers'])) ? $_POST['numbers'] : " "; ?>"/> 
       <option value="null" selected="selected">-</option> 
       <option value="01">01</option> 
       <option value="02">02</option> 
       <option value="03">03</option> 
       </select> 

       <select id="fruits" name="fruits" value="<?php echo (isset($_POST['fruits']))? $_POST['fruits'] : ''; ?>"/> 
       <option value="null" selected="selected">-</option> 
       <option value="Apple">Apple</option> 
       <option value="Banana">Banana</option> 
       <option value="Pear">Pear</option> 

       </select> 

    <input type="submit" value="Send" /> 
    </form> 

解决了这个问题，也许不是一个最好的办法，但至少得到它排序：

<?php 
$item = null; # 
$itemyear = null; 

if(isset($_POST['numbers'])){ 
$item = $_POST['numbers']; 
} 
if(isset($_POST['fruits'])){ 
$itemyear = $_POST['fruits']; 
} 



if(isset($item) && isset($itemyear) && $item != "null" && $itemyear !== "null") 
{ 
    echo "Thank you!"; 
} elseif ($item == "null") { 
    echo "you forgot to choose a number"; 
    } 
    elseif($itemyear == "null") 
{ 
echo "you forgot to choose fruit name"; 
} 



?> 



    <form id="form" name="form" method="post" action=""> 

     <label for="expiry">Select</label> 
      <select id="numbers" name="numbers" /> 
       <option value="null" selected="selected">-</option> 
       <option value="01" <?php if($item == '01'): echo "selected='selected'"; endif; ?>>01</option> 
       <option value="02" <?php if($item == '02'): echo "selected='selected'"; endif; ?>>02</option> 
       <option value="03" <?php if($item == '03'): echo "selected='selected'"; endif; ?>>03</option> 
       </select> 

       <select id="fruits" name="fruits" /> 
       <option value="null" selected="selected">-</option> 
       <option value="Apple"<?php if($itemyear == 'Apple'): echo "selected='selected'"; endif; ?> >Apple</option> 
       <option value="Banana"<?php if($itemyear == 'Banana'): echo "selected='selected'"; endif; ?>>Banana</option> 
       <option value="Pear"<?php if($itemyear == 'Pear'): echo "selected='selected'"; endif; ?>>Pear</option> 

       </select> 

    <input type="submit" value="Send" /> 
    </form> 


<?php 
echo $item ."-". $itemyear; 
?> 

Answer 1

的PHP isset（）函数函数返回true或假（取决于输入是否为...好...设置。

你想要使用这个： value='<?php echo (isset($_POST['numbers'])) ? $_POST['numbers'] : ""; ?>

Answer 2

您不能在<select>上设置value属性。您必须找到正确的<option>并设置其selected属性。就个人而言，我在<select>上放置了data-default属性，然后使用JavaScript循环选项并找到合适的选项。