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Checking if form has been submitted - PHP


Question

What is the best way of checking whether or not a form has been submitted to determine whether I should pass the form's variables to my validation class?

First I thought maybe:

isset($_POST)

But that will always return true as a superglobal is defined everywhere. I don't want to have to iterate through each element of my form with:

if(isset($_POST['element1']) || isset($_POST['element2']) || isset(...etc

Whilst writing this question I thought of a much more basic solution, add a hidden field to act as a flag that I can check.

Is there a 'cleaner' way to do it than adding my own flag?

2011/10/10
1
122
10/10/2011 10:28:55 AM

Accepted Answer

For general check if there was a POST action use:

if (!empty($_POST))

EDIT: As stated in the comments, this method won't work for in some cases (e.g. with check boxes and button without a name). You really should use:

if ($_SERVER['REQUEST_METHOD'] == 'POST')
2015/12/30
191
12/30/2015 9:31:08 AM


Actually, the submit button already performs this function.

Try in the FORM:

<form method="post">
<input type="submit" name="treasure" value="go!">
</form>

Then in the PHP handler:

if (isset($_POST['treasure'])){
echo "treasure will be set if the form has been submitted (to TRUE, I believe)";
}
2013/08/15

Use

if(isset($_POST['submit'])) // name of your submit button
2014/02/26

if ($_SERVER['REQUEST_METHOD'] == 'POST').

2011/10/10

Try this

 <form action="" method="POST" id="formaddtask">
      Add Task: <input type="text"name="newtaskname" />
      <input type="submit" value="Submit"/>
 </form>

    //Check if the form is submitted
    if($_SERVER['REQUEST_METHOD'] == 'POST' && !empty($_POST['newtaskname'])){

    }
2013/01/18

On a different note, it is also always a good practice to add a token to your form and verify it to check if the data was not sent from outside. Here are the steps:

  1. Generate a unique token (you can use hash) Ex:

    $token = hash (string $algo , string $data [, bool $raw_output = FALSE ] );
    
  2. Assign this token to a session variable. Ex:

    $_SESSION['form_token'] = $token;
    
  3. Add a hidden input to submit the token. Ex:

    input type="hidden" name="token" value="{$token}"
    
  4. then as part of your validation, check if the submitted token matches the session var.

    Ex: if ( $_POST['token'] === $_SESSION['form_token'] ) ....
    
2019/12/21

Source: https://stackoverflow.com/questions/7711466
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