Creation of monadic yesod form without hamlet - haskell

Question

My goal is to write a monadic yesod form without usage of hamlet.
Let's say I have such example form:
userForm :: Maybe User -> Html -> MForm Handler (FormResult User, Widget)
userForm u extra = do
(nameR, nameV) <- mreq textField "" (userName <$> u)
(passR, passV) <- mreq passwordField "" Nothing
let userRes = User <$> nameR <*> passR
let widget = do
toWidget $ \render -> do
extra
-- fvInput nameV?
-- fvInput passV?
H.input ! type_ "submit" ! value "Submit"
return (userRes, widget)
In the case of hamlet usage it will be like that:
let widget = do
toWidget [whamlet|
^{fvInput nameV}
^{fvInput passV}
|]
But the return type of fvInput is FieldView App and I need to convert it to Html to compose with blaze well.
Perhaps, it will be easier to use Input Form for this task(i.e. implementing forms without w/hamlet), but the docs on yesodbook say it doesn't have a proper handling of the wrong input case. I tend to use monadic form here since I want a recreation of user input in the case of failed validation "for free" here. Will it work this way?

Answer 1

Use lift with widgetToPageContent:
userForm :: Maybe MyUser -> Html -> MForm Handler (FormResult MyUser, Widget)
userForm u extra = do
(nameR, nameV) <- mreq textField "" (myUserName <$> u)
(passR, passV) <- mreq passwordField "" Nothing
nameContents <- lift $ widgetToPageContent (fvInput nameV)
passContents <- lift $ widgetToPageContent (fvInput passV)
let userRes = MyUser <$> nameR <*> passR
let widget = do
toWidget $ \render -> do
extra
pageBody nameContents render
pageBody passContents render
H.input H.! A.type_ "submit" H.! A.value "Submit"
return (userRes, widget)