php form在發送動作之前檢查數據是否存在

Question

我有一個向另一個頁面發送數據的表單。我想檢查數據是否存在於目錄中，然後重定向，否則顯示錯誤。

<form class="form-inline" method="POST" action="<?php checkMyFile(); ?>"> 
    <select class="form-control" style="width:auto;" name="mydata"> 
     <option value="id1">1</option> 
     <option value="id2">2</option> 
    </select> 
    <button type="submit" class="btn btn-primary">Submit</button> 
</form> 

，我有我的上述HTML窗體頂部以下PHP函數：

<?php 
funtion checkFile(){ 

    if(!isset($_POST['mydata']) or !file_exists('../data/'.basename($_POST['mydata']).'.txt')){ 
     echo $result='<div class="alert alert-danger">Sorry there was an error sending your message. Please try again later</div>'; 

    } else { 

     return "my/destination/page.php" 
    } 

} 

?> 

，但目前它正顯示出沒有錯誤的白頁。 它不工作的原因是什麼？解決辦法是什麼？

Answer 1

試試這個：

變化：

return "my/destination/page.php" 

要：

header('Location: my/destination/page.php'); 

或：

$url = sprintf(
    "%s://%s%s", 
    isset($_SERVER['HTTPS']) && $_SERVER['HTTPS'] != 'off' ? 'https' : 'http', 
    $_SERVER['SERVER_NAME'], 
    $_SERVER['REQUEST_URI'] 
); 

header('Location: '.$url.'/my/destination/page.php'); 

對此部分：

action="<?php checkMyFile(); ?>" 

它更改到你的代碼位於

示例PHP文件：

action="checker.php" 

和內部checker.php是：

if(!isset($_POST['mydata']) or !file_exists('../data/'.basename($_POST['mydata']).'.txt')){ 
     echo $result='<div class="alert alert-danger">Sorry there was an error sending your message. Please try again later</div>'; 

    } else { 

    header('Location: my/destination/page.php'); 
    } 

Answer 2

好吧，讓我們假設這代碼全部在一個叫xxx.php的文件中

首先，您在動作中所能做的只是告訴瀏覽器將哪些腳本發送給表單輸入，您無法在該腳本中指定特定功能。

<?php 
// while testing, always make sure error reporting is on 
error_reporting(E_ALL); 
ini_set('display_errors', 1); 

$errormsg = ''; 

// corrected spelling error of funtion 
function checkFile(){ 

    if(!isset($_POST['mydata']) or !file_exists('../data/'.basename($_POST['mydata']).'.txt')){ 
     return '<div class="alert alert-danger"> 
         Sorry there was an error sending your message. Please try again later 
        </div>'; 

    } else { 

     header("Location: my/destination/page.php"); 
     // exit a you are now sending a new page and this one is irrelevant 
     exit; 
    } 

} 

// was the form submitted, or is this just the page being initially loaded 
// NOTE: I gave the submit button a `name` attribute of `submit` 
if (isset($_POST['submit'])) { 
    $errormsg = checkFile(); 
}  
?> 
<-- Usual doctype/html/head/body tags ommitted for brevity --> 

<?php 
    // output the error message somewhere sensible on your page 
    // which may not actually be here 
    if ($errormsg != '') { 
     echo $errormsg; 
    } 
?> 
<form class="form-inline" method="POST" action="xxx.php" enctype="multipart/form-data"> 
    <select class="form-control" style="width:auto;" name="mydata"> 
     <option value="id1">1</option> 
     <option value="id2">2</option> 
    </select> 
    <button name="submit" type="submit" class="btn btn-primary">Submit</button> 
</form>