How can I extract the name of a $_POST variable, not its value_

Question

I am building a function that will validate the values in a form. How can I extract the actual name in string form from a $_POST variable? Ex: $_POST['first_name'] = 'Joe';

I now want to grab the string 'first_name' and use it in a function to declare a variable by that name. I know I can use a foreach loop but isn't there an easier way to do this?

Answer 1

foreach( $_POST as $key => $value ) {
     $$key = $value;
}

The main difference between using a loop as shown above versus using extract( $_POST ) is that extract puts the variables into global scope, whereas this code will put them in the current scope, thereby making it safer to use than extract

Answer 2

I'm not sure whether this is what you want, but you can use variable variables like so:

$fieldname = "first_name";

$fieldvalue = $_POST[$fieldname];

$$fieldname = $fieldvalue;   // Creates a variable named "first_name"

echo $first_name;  // Outputs the POST variable

Answer 3

I wouldn't use this:

foreach( $_POST as $key => $value ) {
     $$key = $value;
}

...it opens your code to the possibility of someone maliciously setting vars within your program via the form. (i.e., effectively setting globals_register on)

But to answer your core question: your only knowledge of the posted variables is what's in the $_POST array; your only way of finding out what the variable names are is looping through the array keys.

Answer 4

How about

extract($_POST);

Answer 5

As far as I understood, you are looking for array_keys($_POST).

Answer 6

If you want to execute function based on the key name, your best shot would be something like this:

foreach ($_POST AS $key => $value)
{
    call_user_func("example_func_$key", $value);
}

Note the use of $key within the double-quotes of the first parameter of call_user_func. This will allow you to execute a "dynamically" named-function.