Dynamic population - parameter outputs outside the form, but not in form fields

I simplified my function to make the debugging easier:

add_filter('gform_field_value_select_stuff', 'select_stuff');
function select_stuff(){

if (isset($_POST['input_13'])) {
return $_POST['input_13'];
}
}

Still no luck. The result is shown just fine when used outside gravity forms but not when using a parameter_name to dynamically populate a gravity forms field.

When I use echo instead of return in the function, the result shows outside the field above the form though, so I know the value is stored.

Hi,

I am trying to compare a value in my database to a value entered in a gravity form field and when there's a match I want to be able to put results from my database in a gravity forms field (in my case I need to select e-mail addresses).

In:
WHERE wp_usermeta.meta_key='$my_value'

$my_value what's entered in a gravity forms field value so I guess it could be this as well:

WHERE wp_usermeta.meta_key=$_POST["input_13"]

I then use the parameter name 'select_stuff' to try and dynamically populate my form field with the result of the function.

But in Gravity Forms it won't output the result in a field. When I execute the function anywhere else in the page (outside gravity forms) or use a custom html form input field, it does show the result just fine.

I just tested again with this simple code in my functions.php file.

add_filter('gform_field_value_select_stuff', 'select_stuff');
function select_stuff(){
return $_POST["input_13"];
}

Works anywhere on my page except when I use parameter name 'select_stuff' in a Gravity forms field.

The result of this part "No Match":

if(mysql_num_rows($result)==0){
return "No Match";
}

DOES show in my gravity form field with the parameter set, even though the previous condition is met...

Hope it's somewhat clear..:)

You are right, tried this before as well but it didn't work.

input_13 is a field in the same form.
The value entered in that field is used to compare with database values.
There is a result when there's a match and this result should be returned in a separate field.

The code works used as regular php. But in gravity forms "No Match" is what always shows in the result field, because somehow it looks like it loses the variable entered in 'input_13'

Exactly, I wish I could have been that clear from the start :D