对于html表单输入，PHP总是将$ _POST数组isset /！empty / sizeof> 0评估为true

I have a basic form to upload an image:

<?php
  if(!empty($_POST['?upload_img'])) {
      echo "true<br>";
  } else { echo "false<br>"; }
?>

<html>
  <form action='' method='post' enctype='multipart/form-data'>
    <input type='file' name='input_img' id='input_img'><br>
    <input type='submit' value='Upload Image' name='?upload_img'>
  </form>
</html>

I would like a PHP boolean/evaluation pair to run only once for each upload.

I have tried evaluating using !empty,isset,sizeof(foo)>0

I have also tried to find a solution using $_SESSIONs

Is there are correct use of unset or $_POST=array()/$_FILE=array() that I have missed?

I can achieve the desired behaviour with sessions:

<?php
  session_start();
  if(!empty($_SESSION['foo'])) {
    echo "true<br>";
  } else { echo "false<br>"; }
?>

<html>
  <?php
    if(!sizeof($_SESSION['foo'])) {
      $_SESSION['foo']=array();
      $_SESSION['foo']['bar']="path/to/the/file.png";
    } else { $_SESSION=array(); }
  ?>
</html>

How can I achieve the same with input from a <form> instead?

Any help is much appreciated!

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2条回答默认最新

duanjiaonie6097 2018-05-05 00:39

关注

For completeness, an outline approach specific to my issue:

<!--filename:foo.php-->
<?php
  session_start();
  if(isset($_POST['?confirm'])) {
    $_SESSION['input']=$_FILES['input'];
    header("HTTP/1.1 303");
    header("Location: http://$_SERVER[HTTP_HOST]/foo.php");
    die;
  } else if(!empty($_SESSION['input'])) {
    echo "true<br>";
    session_unset();
    session_destroy();
  } else { echo "false<br>"; }
?>
<html>
  <form action='foo.php' method='post' enctype='multipart/form-data'>
    <input type='file' name='input' id='input'><br>
    <input type='submit' value='confirm' name='?confirm'>
  </form>
</html>

Based on Post-Redirect-Get Pattern in PHP

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