[web2py] How to search by date?

[cyber]

I have a couple of <INPUT class="date"> to search in a date range.

<FORM action="search_results">
    <input name="date1" />
    <input name="date2" />
    <input type="submit" />
</FORM>

I thought over a search code like this:

def search_results():
    d1=request.vars.date1
    d2=request.vars.date2
    results=db(db.autos.dt<=d1 & db.autos.dt>=d2).select()
    return dict(results=results)

But it doesn't work because of unconvinuent date/object format.

So, how to convert d1 and d2 => [2011-04-26] => into the date and
build correct search code?
Any ideas!?!