How to keep the url on the same page after form validation?

[eluser]123wesweat[/eluser]
Tx rogier
[quote author="rogierb" date="1266609129"]There are several ways to go about:

1: change your form action so it stays in the same url and check for count($_POST)
2: use flashdata to store the old url.
3: several other ways, like storing where you came from in a $_POST variable etc[/quote]

@1, ??? check if something is submitted and then do the validation??? So i must do the count($_POST) in the index function

I do have routing enabled, so test/banksy will always activate the show_content function. And i like to stay on test/banksy.
And i would like to show a thank you message??

@2 will look that up

@3 hope 1 or 2 will work for me