为什么 HTML 不会在 PHP 中选择表单元素 $_POST 多个值？

Question

if (isset($_POST['ids']) && $_POST['ids'] === 'ford') {
  echo "yah!!!";
  print_r($_POST);
  $filename = "ford.txt";

} elseif (isset($_POST['ids']) && $_POST['ids'] === 'toyota') {
  print_r($_POST);
} elseif (isset($_POST['landrover']) && $_POST['ids'] === 'landrover') {

} elseif (isset($_POST['algonquin']) && $_POST['ids'] === 'algonquin') {

} elseif (isset($_POST['errors']) && $_POST['ids'] === 'errors') {

}

testing to see if $_POST superglobal array is posting. It is only posting one value 'ford'. Not sure why none of the other values aren't posting.

<form name="form" method="post" action="<?php echo $filename; ?>" target="box" >
    <select name="ids">
      <option value="ford">Ford</option>
      <option value="toyota">Toyota</option>
      <option value="landrover">Land Rover</option>
      <option value="algonquin">Algonquin</option>
      <option value="errors">Errors</option>
    </select>
    <input type="submit" name="submit" value="View File" />


  </form>

This is the form with all of the options and their values. It has a variable $filename which links to a text file which is meant to be opened in a target box. The if statement above is supposed to determine what file to open.

<iframe src="" name="box" width="100%" height="100%" frameborder="0"></iframe> The iframe or target box the file is supposed to open in.

Answer 1

If you wish to POST multiple values from your <SELECT> , you will need to make a few modifications.

Let's start with your form...

<form name="form" method="post" action="selections.php" target="box" >
    <select name="ids[]" multiple>
        <option value="ford">Ford</option>
        <option value="toyota">Toyota</option>
        <option value="landrover">Land Rover</option>
        <option value="algonquin">Algonquin</option>
        <option value="errors">Errors</option>
    </select>
    <input type="submit" name="submit" value="View File" />
</form>
<iframe name="box" width="100%" height="100%" frameborder="0"></iframe>

1. Your form will need to be received by a .php file, not a .txt file. I'm not sure what you are trying to do with $filename .
2. If you want to allow multiple selected options on your form, make the name value an array like: ids[] and write multiple inside the <select> .
3. If you don't need the submit value on your POST receiving file, then you don't need to write a name attribute on <input type="submit">

---

On your submission receiving page (let's call it selections.php ), the `$_POST array can look like the following:

If you selected Ford , then:

$_POST=array('ids'=>array('ford'),'submit'=>'View File');

If you selected Toyota and Errors , then:

$_POST=array('ids'=>array('toyota','errors'),'submit'=>'View File');

If no selections are made, then :

$_POST=array('submit'=>'View File');

To check this SUPERGLOBAL data, you can use the following:

<?php
if(!isset($_POST['submit'])){
    echo "No submission data";
}elseif($_POST['submit']=='View File'){
    echo "Invalid/Unexpected submit data";
}elseif(empty($_POST['ids'])){
    echo "No ids selected";
}else{
    $valid_ids=['ford','toyota','landrover','algonquin','errors'];
    $_POST['ids']=array_intersect($_POST['ids'],$valid_ids);  // validate
    foreach($_POST['ids'] as $id){
        // do whatever you like with $id , perhaps $filename=$id.".txt" or something
    }
}

Answer 2

This is presumably happening because you're not checking the $_POST['ids'] value in the following if conditions. I would wager that if you selected 'toyota' it would work.

This is what your code should look like

if (isset($_POST['ids']) && $_POST['ids'] === 'ford') {
  echo "yah!!!";
  print_r($_POST);
  $filename = "ford.txt";

} elseif (isset($_POST['ids']) && $_POST['ids'] === 'toyota') {
  print_r($_POST);
} elseif (isset($_POST['ids']) && $_POST['ids'] === 'landrover') {
  print_r($_POST);
} elseif (isset($_POST['ids']) && $_POST['ids'] === 'algonquin') {
  print_r($_POST);
} elseif (isset($_POST['ids']) && $_POST['ids'] === 'errors') {
  print_r($_POST);
}

Edit: as mentioned above, it seems like you're implying that the form should go to ford.txt?