[英]Modifying form submission data before it gets sent to stringRead
我有一个Digestive Functors表单,如下所示:
dateTimeForm :: Monad m => Maybe LocalTime -> Form Text m LocalTime
dateTimeForm t = LocalTime
<$> "date" .: stringRead "Must be a valid date" (localDay <$> t)
<*> "time" .: stringRead "Must be a valid time" (localTimeOfDay <$> t)
我用于此表单的输入元素是<input type="date" />
和<input type="time" />
。 这适用于此表单的日期部分,但在时间部分不太好。 支持时间输入元素的浏览器仅提交小时和分钟(例如“18:00”),但TimeOfDay需要小时,分钟和秒。 这会导致stringRead失败并且Digestive Functors向用户报告错误(“必须是有效时间”)。
我尝试解决这个问题,但如果用户提交的时间无效,他们就不会再从Digestive Functors中获得一个有吸引力的错误(Prelude.read:no parse)。
dateTimeForm :: Monad m => Maybe LocalTime -> Form Text m LocalTime
dateTimeForm t = toLocalTime
<$> "date" .: stringRead "Must be a valid date" (localDay <$> t)
<*> "time" .: string (show . localTimeOfDay <$> t)
where
toLocalTime d x = LocalTime d $ read $ if length x == 8 then x else x <> ":00"
我想我要找的是validate
功能和maybeRead
的一些帮助。 这似乎有效:
dateTimeForm :: Monad m => Maybe LocalTime -> Form Text m LocalTime
dateTimeForm t = LocalTime
<$> "date" .: stringRead "Must be a valid date" (localDay <$> t)
<*> "time" .: validate validTime (string (show . localTimeOfDay <$> t))
where
-- the time input element only submits hours and minutes ("18:00"), which is 5 characters long
validTime x = case maybeRead (if length x == 5 then x <> ":00" else x) of
Just x' -> Success x'
_ -> Error "Must be a valid time"
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.