adding URL parameters to a form PHP HTML

Question

Is it okay or correct to put a url get parameter in a form action?

<form method='get' action='index.php?do=search'>
  <input name='_search' type='text' value='What are you looking for?'>
  <button type='submit'> Search </button>
</form>

When I submit the form the URL is changed to:

index.php?_search=What are you looking for? (I've stripped %20)

I'd prefer the URL to read

index.php?do=search&_search=What are you looking for?

Would it be best to add a hidden field into the form

<input type='hidden' name='do' value='search' />

Answer 1

In my opinion you should add them as hidden fields. There is no point to try to pass params if you can do it via hidden form field

use that:

<input type='hidden' name='do' value='search' />

Answer 2

A don't see any reason why you can't or shouldn't do it that way. My preferred method of handling it however would be:

<form method='get' action='index.php'>
    <input name='_search' type='text' value='What are you looking for?' />
    <submit name='do' value='Search'>
</form>

The name/value pair of do/search is passed through the button press, and if you want to create multiple actions on a form you can then have different values for each submit button, handling the form in multiple ways.

if ($_GET['do'] == "Search") {
 ... do Search ...
} else if ($_GET['do'] == "Foo") {
 ... do Foo ...
} else if ($_GET['do'] == "Bar") {
 ... do Bar ...
}

alternatively you can use a case construct:

switch($_GET['do']) {
    case "Search":
        ... do Search ...
    case "Foo":
        ... do Foo ...
        break;
    case "Bar":
        ... do Bar ...
        break;
} 

I normally use post myself, but I am sure get would work the same way. Hope that answers your question.