Hello,
I hacked your code into a runnable example, and it seems to work for me. What happens if you do something like:
let (c, xml, _) = runFormState [("input0",Left "name"), ("input1", Left "password"), ("input2", Left "password") ] "" (register "foo") in c >>= \r -> do print xml >> print r
(except you need to pass in a Database instead of "foo" as the argument to register.)
I get:
Username
Which looks correct to me. Your code looks fine to me as
well... Perhaps the error is not in the code you pasted, but somewhere
else. I am running on an older, and somewhat forked version of
Formlets, so there could also be a bug in the new code I
guess. Though, that seems unlikely. But it is worth noting that we are
not using the same version of the formlets library.
- jeremy
At Thu, 27 Aug 2009 16:09:18 +0100,
Colin Paul Adams wrote: I'm trying to validate user input against a database (using HaskellDB,
but that doesn't seem to be the problem, as replacing the database
monadic code with return True gives the same problem. This is part of my code: register :: Database -> XForm Registration
--register db = Registration <$> pure_user <*> passConfirmed
register db = Registration <$> (user db) <*> passConfirmed user :: Database -> XForm String
user db = pure_user `F.checkM` F.ensureM valid error where
valid name = do
let q = do
t <- table user_table
restrict (t!user_name .==. constant name)
return t
rs <- query db q
return $ null rs
error = "Username already exists in the database!" pure_user :: XForm String
pure_user = input `F.check` F.ensure valid error where
input = "Username" `label` F.input Nothing
valid = (>= 3) . length
error = "Username must be three characters or longer." passConfirmed :: XForm String
passConfirmed = fst <$> passwords `F.check` F.ensure equal error where
passwords = (,) <$> pass "Password" <*> pass "Password (confirm)"
equal (a, b) = a == b
error = "The entered passwords do not match!" pass :: String -> XForm String
pass caption = input `F.check` F.ensure valid error where
input = caption `label` F.password Nothing
valid = (>=6) . length
error = "Password must be six characters or longer." If I uncomment the commented line, and comment out the line after it
(in register), then everything works as expected. However, using it as
it is, one of the calls to pass gets the user's name for validation
(and consequently either fails if the user name is only 5 characters,
or the comparison of the two passwords fail (unless I type the user
name as the password). I thought the applicative style meant the effects did not influence
one another, but here there is clear contamination. What am i doing wrong?
--
Colin Adams
Preston Lancashire
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